Concepts in Chemistry

CHAPTER-II

IUPAC NOMENCLATURE OF ALIPHATIC COMPOUNDS CONTAINING ONE FUNCTIONAL GROUP

ALKANES There are two types of alkanes: (i) Straight chain alkanes(unbranched alkanes): If all the carbon atoms are connected in series one after the other and nowhere there is any branching, we call it a straight chain alkane. Note that you may write such an alkane in a twisted way, but it remains as a straight chain. See these examples.

C CC CC CC CCCCCC CC CC C In all the above cases the carbon atoms are connected in straight chain although in the second and third cases the carbon skeletons have been written in a twisted manner. There is no branching in any of them. If you attach the required number of hydrogen atoms, each structure is same and it is hexane. So the alkanes- methane, ethane, propane, butane, pentane, hexane, heptane etc. that we learnt in Chapter-I belong to the category of straight chain alkanes and these are their IUPAC names. But never think that their structures are really linear. Each carbon atom is tetrahedral in geometry i.e the the bond angles are 1090 28'. So the shape of alkanes is 3-dimensional. (ii) Branched alkane : If larger number of carbon atoms connected in series make the main or principal carbon chain and fewer number of carbon atoms are attached to the principal chain at different positions forming branches, we call it a branched alkane. See these examples. 5 1 C 1 2 3 4 56 4 3 2 1 C 2 3 4 CCCCCC CCCC C CC C C C C In the first example, there is a branch of one carbon atom attached to the 2nd carbon atom(from LHS) of the main chain. In the second example, there is a branch of one carbon atom attached to the 2nd carbon atom counted from the RHS of the main chain. In the third case, there are two branches, one at the 2nd carbon atom from LHS and the other at 2nd carbon atom from RHS(4th carbon atom from LHS) of the main chain containing 5 carbon atoms. NAMING OF BRANCHED ALKANES: (i) For branched alkane, first the longest continuous carbon chain is selected. For doing so,

one has to start from one terminal(end) carbon(CH3) and go upto the other terminal carbon(CH3) and see in which direction, the number of carbon atoms is maximum. (ii) Number the carbon atoms with numerals 1,2,3..... This is the principal carbon chain of alkane. For example, if the principal chain contains 5 carbon atoms, it is pentane, and if it contains 4 carbon atoms it is butane and so on. Nomenclature of Organic Compounds

(iii) The other carbon atoms which do not belong to the main chain form the branches or substituents. Mark these substituents as shown below.

1 2 3 4 5 6 CH3 CH CH2 CH2 CH2 CH3 2-methylhexane(correct)

CH3 Here the longest chain contains six carbon atoms. Hence the parent alkane is hexane. But there is a branch at carbon number 2. The name of the substituent is methyl. You

already know the names of different alkyl groups like methyl(CH3-), ethyl(CH3CH2-),

propyl(CH3CH2CH2-) and so on. (iv) The position(number) of carbon atom to which the branch(sustituent) is attached is called the locant of the substituent. Here the locant of methyl group is 2 as it is attached to carbon number 2 of the main chain. (v) First the name(s) of the branch is(are) written. Branch name is preceded by its locant followed by '-"(hyphen) mark e.g 2-methyl in this case. Then the name of the alkane is written. There should be no space between the branch name and the name of parent alkane. Hence the name of the above alkane is : 2-methylhexane ( not 2-methyl hexane)

PROCEDURE FOR GENERAL NOMENCLATURE branches + Word root +suffix In alkane, suffix is -ane. So, for alkanes the name becomes branches + alkane BRANCHES : Locants are prefixed to each branch(substituent) using hyphens (-) to separate the locants from the names of branches, e.g 2-methyl, 4-ethyl etc. If there are two or more of the same branch(say methyl or ethyl or any other) in a given molecule, then the multiplying prefixes di, tri, tetra, penta, hexa, hepta etc., are used together with a set of locants, one for each of the branches with the locants separated by commas. In such case the hyphen(-) is given after the last locant i.e before the name of the branch.For example, if there are three methyl groups out of which two are attached to C-2 and the third is attached to C-3, then the branches are to be written as 2,2,3-trimethyl(neither 2,3-trimethyl nor 2,2-dimethyl-3-methyl). Note that each and every branch must have a locant, even if it requires repeating the identifier as in 2,2-dimethyl. (vi) Alphabetical ordering: The substituents(branches) are arranged according to alphabetical order of the first letters of the branches. The terms di-, tri- tetra- etc., used as multiplying prefixes of the substituents are not considered for alphabetical ordering. Wrong order : 2,3, 3-trimethyl-3,4-diethyl-4-butyl-5-propyl Correct order : 4-butyl-3,4-diethyl-2,3,3-trimethyl-5-propyl Note that the prefixes di, tri are not considered for alphabetical ordering of branches. Full name: 4-butyl-3,4-diethyl-2,3,3-trimethyl-5-propyldodecane (correct) 4-butyl-3,4-diethyl-2,3,3-trimethyl-5-proply dodecane (incorrect) Concepts in Chemistry

There should not be any space between the name of the last branch and the name of the parent alkane. In the second case, there is a space between the last branch propyl and the parent alkane dodecane. To be specific, there should not be any vacant space anywhere in the name. (vii) LOWEST LOCANT RULE OR LOWEST SET OF LOCANTS RULE: Lowest Locant Rule: When there is only one branch this rule is followed. According to this rule, that direction of numbering the principal carbon chain is correct which gives the lowest locant to the substituent(branch) and the corresponding name is the correct name. This is achieved by writing names two times, first with one direction of numbering and next with reverse direction of numbering. The numbering of carbon atoms is reversed with respect to first numbering in the same chain. The last carbon becomes the first carbon while the first carbon becomes the last carbon in the new numbering system. Look at this example. 1 2 345 6 5-methylhexane(wrong) CH3 CH CH2 CH2 CH2 CH3 6 5 432 1 2-methylhexane(correct) CH3

According to numbering from left to right the methyl(CH3) group is attached to carbon

No. 2. So its locant is 2. According to the numbering from right to left methyl(CH3) group is attached to carbon No. 5. So, its locant is 5. According to this rule, the name having lowest locant of the branch is the correct name. Hence the correct name of the alkane is 2-methylhexane, (not 5-methyhexane). Note that the direction of numbering the carbon chain can be done by mere inspection without reversing the numbering system. IMPORTANT : The direction in which a substituent is ecountered first is the correct direction of numbering. Lowest set of locants rule : When there are more than one branches, lowest set of locants rule is followed. The numbering of the main chain is done in the direction which gives the lowest locant to the first branching point. In other words, the direction in which a branch is met earlier is the correct direction of numbering. That gives the lowest set of locants. See this example. Example

CH3 2 4 CH 1 3 CH2 CH2 5 CH H3C CH CH 3 6 8 5-ethyl-2,3-dimethyloctane(correct) CH3 CH2 7 CH3 CH2 The longest chain contains eight carbon atoms. So the parent alkane is octane. Let us now look to the branches. There are three brances, two methyl(CH3) attached to C-2, C-3, and one ethyl(-CH2-CH3) attached to C-5. So, the name is 5-ethyl-2,3-dimethyloctane (correct) Nomenclature of Organic Compounds

Reverse the number system:

CH3 7 5 CH 8 6 CH2 CH2 4 CH H3C CH CH 3 3 1 4-ethyl-6,7-dimethyloctane(wrong) CH3 CH2 2 CH3 CH2 According to this numbering, the name is 4-ethyl-6,7-dimethyloctane. Lowest Set of Locants Rule: Write the locants of all the substituents in each name in increasing numerical value and make a set. In the first name, the set is : 2, 3, 5 (lowest set of locants) In the second name, the set is : 4, 6, 7 When comparison is made between the two sets from the beginning, locant by locant, the set giving the lower locant at the first point of difference is called the lowest set of locants irrespective of the locants appearing at later positions. This lowest set gives the correct name. So, the correct name is 5-ethyl-2,3-dimethyloctane. Example :

CH3

2 4 6 8 10

1 CH2 3 CH 5 CH2 7 CH2 9 CH3 9 7 5 3 1 H3C CH CH2 CH2 CH 10 8 6 4 2

CH3 CH3 The longest chain contains ten carbon atoms, hence the parent alkane is decane. Two names that can be proposed with respect to both forward and backward numbering systems are 3,4,9-trimethyldecane (wrong) 2,7,8-trimethyldecane (correct) When we compare the two sets i.e (3,4,9) and (2,7,8) we find the difference at the first point. In first set, the first number is 3 and in the second set, it is 2. This suggests that the second set is the lower set of locants and thus the correct name is 2,7,8-trimethyldecane. Note that after meeting the first point of difference, the other locants are not compared. The comparison is stopped from there. Note also, that if we take the sum of the locants in the two sets, we get, sum of locants in the first set = 3 + 4 + 9 = 16 sum of locants in the second set = 2 + 7 + 8 = 17 Although the sum of the locants in the second set is greater than the first, the second set gives the correct name. Hence lower sum of locants is never considered for getting the correct name. It is the lowest set of locants which is considered for the purpose. Concepts in Chemistry

TRICK : In order to know which direction of numbering the longest chain would give the lower set of locants, you are advised to do it by mere inspection. This would save a lot of time. The direction which gives lower locant(number) to the first substituent gives the correct direction. That direction of numbering will certainly give the lowest set of locants and hence correct name irrespective of the locants of the other substituents present in the chain. If the first substituent from both the directions have the same locant, then the next substituent is compared, if that tallies then the next is compared until a point of difference is met. The one giving lower locant at the first point of difference gives the correct direction of numbering. (viii) Alphabetical priority when sets of locant are same: In case, the sets of locants of the substituents are same in both the directions of numbering of longest carbon chain, then an alphabetically senior group gets the lower locant.

CH3 3-methyl-4-ethylhexane (wrong) 5 CH2 1 3 3-ethyl-4-methylhexan (correct) CH2 4 CH 2 CH3 2' 6' 6 CH 4' H3C 3' CH2 1' 5' CH3

In both the directions, the sets are same(3,4). In the direction from right to left the alphabetically senior group ethyl gets lower locant (3), hence the correct name is 3-ethyl-4-methylhexane.

(ix) Branching Rule: If longest chain is available in more than one direction, then the one to which maximum number of branches are linked is selected as the correct longest chain.

CH3 CH3 2 4 6 2 4 CH 7 CH 1 3 CH2 CH2 1 3 CH2 CH2 5 CH 5 CH H3C CH CH 3 H3C CH CH 3 6 CH3 (wrong) CH3 (correct) CH CH 7 CH3 CH3 CH3 CH3

Here we find that the longest chain of seven carbon atoms are found in two directions. But which direction we shall follow? In the first case, we find the chain has three branches , one at C-2, the second at C-3 and the third at C-5. Note that the big group attached to C-5 is called

H3C propan-2-yl CH group(to be discussed later). The whole group is considered to be one H3C branch as it is connected with the main chain with a single bond. In the second case, the chain is connected with four branches at C-2, C-3, C-5 and C-6. According to branching rule the chain which is connected with more number of branches is the correct longest chain. So the second one is correct. The name is 5-ethyl-2,3,6-trimethylheptane. Nomenclature of Organic Compounds

Example

8' 7' CH3 H C CH CH 8 3 2' 3 2 4 6 CH3 7 CH CH 5 CH 1' 3 CH H 3 C CH CH 2 C CH3 CH3 H C 3 1 CH3 CH3

In this case, longest carbon chain containing 8 carbon atoms are available in more than one direction. Out of those, the one numbered as 1,2,3,4,5,6,7,8 is the correct longest chain as it is attached with maximum number of branches(seven). All other longest chains namely 1',2',3,4,5,6,7,8 or 1,2,3,4,5,6,7',8' or 1',2',3,4,5,6,7',8' are attached with less number of branches. Note that in each chain, the terminal(first and last) carbon atom could have been the carbon atom of the other methyl(CH3-) group. Terminal CH3- groups are equivalent and you can select any one for the numbering purpose. LINE STRUCTURE FOR BRANCHED ALKANES : The branched alkanes can be represented by line structures like unbranched alkanes. Each terminal point, each bent point and each crossing point in the line structure carries one carbon atom and each carbon atom is linked with required number of hydrogen atoms. Before naming convert first the line structure into actual structure by writing carbon atoms at each terminal, bent and crossing points and attaching required number of H atoms to each carbon.

1 H3C 2 CH3 CH CH3 7 3 5 CH3 CH 4 CH 6 CH2 8 = CH2 CH CH CH3 CH2 CH3 CH3 The name of the above compound is 3,4-diethyl-2,5,6-trimethyloctane. The longest chain selected is correct as it has maximum number of branches(branching rule). The direction of numbering chosen is correct because a branch(methyl) is encountered earlier in that direction at C-2(lower set of locants rule). SAQ II. 1: Give the IUPAC names of the following:

CH3 CH2 CH3 H3CCHCH2 CH3 CH CH3 CH CH3 CH2 (i) H3C CH (ii) (iii) H3CC CH3 CH3 CH2 CH3 CH3 Concepts in Chemistry

CH3 H3C CH CH3 3 CH3 CH3 CH CH2 H CCCH H CC CCH (iv) (v) 3 3 (vi) 3 3 H3C CH CH CH3 CH3 CH3 CH2 CH2 CH3

(vii) (viii)

SAQ II.2: Give the structural formula of the following compounds. (i)2,3-dimethylpentane (ii)3-methylhexane (iii)2,2,4-trimethylhexane (iv)2-methylpropane SAQ II.3: Some incorrect names are given. Write the structure of alkanes from them. Also give the correct names. (i)3-methylbutane (ii)2-ethylpropane (iii)4,5-dimethylhexane

NAMING COMPLEX SUBSTITUENTS(BRANCHED BRANCHES OR SUBSTITUTUED SUBSTITUENTS) : (Substitutive Names of Complex Branches)

Simple branches : These are derived from straight chain(unbranched) alkanes by removing one H atom from a terminal carbon. In such case 'ane' is replaced by 1-yl, eg. propyl, butyl, pentyl. In these case the locant of yl is 1- and is dropped. The locant of carbon which bears the unsatisfied valency of the alkyl group is the locant of yl. Always the locant of -yl should be minimum.

The alkyl branches such as methyl(CH3-), ethyl(CH3-CH2-), propyl(CH3-CH2-CH2-), butyl, pentyl etc. are called simple branches as the locant of -yl is 1 and moreover there is no sub-branches. The numbering in a branch starts from one terminal and continues till other terminal, just like it is done in the principal carbon chain such that the locant of 'yl' becomes lower.. Complex branches: Under the following conditions an alkyl branch is called complex. (a) The locant of 'yl' is not 1. In such case, the last letter 'e' of the suffix 'ane' is replaced by 'yl' with the locant of 'yl' coming before it. For example : propan-2-yl, butan-2-yl(not prop-2-yl or but-2-yl). Note that such a branch may or may not have sub-branches. (b) Even though the locant of 'yl' is 1, if the alkyl branch is futher branched i.e the branch has one or more sub-branches. In such case, the sub-branches is written first followed by the main branch. For example : 2-methylpropyl. In both the cases, the branch with its internal locants(both locants of sub-brances and locant of 'yl') are kept inside a parenthesis. The locant of the complex branch attached to the principal carbon chain is written before the parenthesis carrying the complex branch. For example : 2-(propan-2-yl); 3-(2-methylpropyl) etc. Note that the locant inside the parenthesis belongs to the branch and the locant outside the parenthesis belongs to the principal carbon chain. Nomenclature of Organic Compounds

3 2 3 2 1 CH3 CH CH3 CH2 CH2 1 CH 3 propyl propan-2-yl

4 3 2 4 3 2 1 CH3 CH2 CH CH3 CH2 CH2 CH2 1 CH3 butyl butan-2-yl

1 CH CH3 3 CH3 3 1 3 3 2 2 1 2 CH CH CH CH C CH CH3 C 3 2 3 2 CH CH3 2-methylpropyl 3 2-methylpropan-2-yl 2,2-dimethylpropyl (Note that terminal carbon is the carbon which is attached to only one carbon while internal carbon is bonded to more than one carbon. In the old IUPAC rule, the carbon directly bonded to the principal carbon chain was numbered 1 and from that the longest chain of the branch was determined. Propan-2-yl was named as 1-methylethyl while butan- 2-yl was named as 1-methylpropyl and 2-methylpropan-2-yl was named as 1,1-dimethylethyl etc.. Some literature also give these olden names for complex branches. But these are not preferred IUPAC names(PIN) now. Moreover IUPAC was also using the names isopropyl for propan-2-yl, sec-butyl for butan-2-yl and isobutyl for 2-methylpropyl and tert-butyl for 2-methylpropn-2-yl as offical names for these branches. However these names are also not now in use)

Alphabetical ordering of the complex branch: * The first letter of a complex branch is considered for alphabetical priority. This will include the multiplying prefixes such as di-, tri- etc. For example, the complex branch (2,2-dimethylbutyl), the first word 'd' is considered. But the same is not considered for simple branches such as dimethyl, triethyl etc. * If the first word of a complex branch is same as a simple branch, eg. 2- methylpropyl(complex branch) and methyl(simple branch) then the simple branch is written first and the complex branch next. In other words when two groups have same initial words(or letters), the longer branch is alphabetically junior and hence placed later. Example: 6-methyl-2-(2-methylpropyl)....(correct); 2-(2-methylpropyl)-6-methyl...(wrong). Concepts in Chemistry

3' 1' 2 4 2' 10 12 3 5 1 6 7 8 2' 9 1' 3' 11

6-methyl-8-(2-methylpropan-2-yl)-5-(2-methylpropyl)dodecane Note that the correct direction of numbering is from left to right as the first branch appears as it follows lower set of locants rule (5,6,8). The reverse direction would have given the set (5,7,8). Note that the prime symbols(1', 2' 3' etc) given in carbon atoms of branches are removed while the names are put inside parentheses. The locants inside parenthesis belongs to the numbering of carbons of branch while the locants outside the parenthesis belongs to the principal carbon chain.

* When two longest chains having same lengths and same number branches compete, the longest chain which gives the lower set of locants for the branches is the correct longest chain. Look at this example.

H3C

2 4 6 8

H3C 3 1 5 7 CH3 9 CH3 8 6 H3C 7 CH3 9 2,6-dimethyl-5-(2-methylbutyl)nonane In this case the longest chain of nonane can be traced in two directions from C-5 ; one towards the right and other below. Both the longest chains have same number of branches( two methyl groups). In such a case, the longest chain which gives the lowest set of locants for the branches is the correct one. In the chain which proceeds towards the downward direction from C-5 gives the set of locants 2,5,6 and the chain which proceeds towards the right of C-5 gives the set of locants 2,5,7. The former being the lowest set(obtained at the third point of difference) is the correct longest chain. Hence the correct name is 2,6-dimethyl-5-(2-methylbutyl)nonane. Since (2-methylbutyl) is a complex branch it has been placed after 2,6-dimethyl as the latter are simple branches. * When there are more than one identical complex branches having the multiplying prefix di, tri, tetra etc. within their substitutive names, the multiplying prefixes di, tri etc. are not used prefixed to such branches. Instead, the multiplying prefixes bis, tris, tetrakis etc. are used. See this example. 2,3-bis(propan-2-yl) or 3,4-bis(2,2-dimethylpropyl) etc. Nomenclature of Organic Compounds

3'

1' 2' 2 4 10 12 3 5 1 6 7 8 9 11 2' 1'

3' 6,6-bis(2,2-dimethylpropyl)dodecane Since the term di lies within the parenthesis in the complex branch, the multiplying prefix bis is used, not di again. Bis, tris.... prefix is also used for all complex braches defined earlier whether or not they carry di-, tri- ..... in their names. However in case of complex branch not having di-, tri- inside it like propan-2-yl, the multiplying prefix di-tri can also be used in place of bis- tris- etc as a matter of choice. However it is not PIN. * FIRST LETTER CAPITALIZATION: Nowhere IUPAC has recommended to make the first letter of the name capital e. g 2,3-Dimethylbutane, 2,3,3-Trimethylpentanoic acid etc. This is a convention followed in some countries such as Germany. That is why some authors give stress on first letter capitalization as a matter of IUPAC rule. But to this author, it is not a rule, but a matter of convention. COMMON(TRIVIAL) NAMES FOR SOME COMPLEX BRANCHES: The following complex alkyl branches have their common or traditional names. In some literature you may might find their usage in IUPAC system. So you must know them now.However these are not preferred IUPAC names.

CH3 CH CH3 CH CH2 CH3 CH CH2 CH2 CH3 CH CH3 3 isopropyl isobutyl isopentyl or isoamyl

CH3 CH CH2 CH2 CH2 CH3 CH2 CH CH 3 isohexyl sec-butyl CH3

CH3 CH3 CH3

CH3 C CH3 C CH2 CH3 CH2 C

CH3 CH3 CH3 tert-butyl neopentyl tert-pentyl Note that all the carbon atoms present in a complex branch are considered for naming with the prefix iso, sec, tert., neo. The carbon atoms are not numbered in these cases like those in the other systems explained before. We shall discuss more about these groups later in Chapter-IV.

The prefixes iso, neo are not followed by a hyphen while sec- and tert- are followed by Concepts in Chemistry hyphen(-) symbol. In other words isobutyl is one word but tert-butyl are two words separated by –. For alphabetical ordering therefore iso and neo were considered while tert- and sec- were not. However these names are not used in present time. Example:

CH CH3 3 CH 4-isopropyl-3-methylheptane 2 4 6 3 5 1 7

CH3

The PIN of this compound is 3-methyl-4-(propan-2-yl)heptane.

SHORT REPRESENTATIONS OF SOME COMMON ALKYL GROUPS: The following abbreviations are used for the alkyl groups written against their names. methyl Me isobutyl i-Bu ethyl Et sec-butyl s-Bu n-propyl n-Pr tert-butyl t-Bu isopropyl i-Pr n-butyl n-Bu

SAQ II.4: Give the IUPAC names of the following compounds shown in line drawings.

(i) (ii)

(iii) (iv) Nomenclature of Organic Compounds

(v) (vi)

(vii) (viii)

(Rule for naming compound (viii): When two or more longest chains containing same number of branches and same set of locants for the branches compete with each other, IUPAC recommends that the longest chain which contains greatest number of carbon atoms in the branches is correct. So the chain bearing ethyl group gives the correct longest chain. In all other chains the branches are methyl which is shorter than ethyl).

(ix) (x)

(xi) (xii)

(xiii) (xiv)

SAQ II.5: Draw the line structures for the following molecules. (i) 5-(2-methylpropy)dodecane (ii) 4-(propan-2-yl)-4-propylnonane (iii) 5-(butan-2-yl)-5-(propan-2-yl)decane (iv) 4,4-bis-(2-methylpropan-2-yl)heptane (v) 3-ethyl-6-(5-methylhexan-3-yl)-8-(propan-2-yl)undecane Concepts in Chemistry

ALKENES: Alk is the root word and ene is the suffix for alkene. (i) ene of alkene has a locant(number) of its own. The first carbon atom of the double bond(C=C) gives the locant(number) of the ene.In otherwords this locant identifies the lowest numbered carbon of the two carbon atoms of C=C with respect to the terminal carbon numbered as C-1 . This locant is written between root word and suffix. See this example.

1 2 3 4 1 2 3 4 H2CCHCH2 CH3 (but-1-ene) CH3 CH CH CH3 (but-2-ene) but- is the root word and -ene is suffix. In the first example, the double bond follows C-1, so the locant of ene is 1 which is written just before ene. In the second example, the double bond follows C-2 and so the locant of ene is 2. Placing the locant before root word like 1-butene, 2-butene is not the preferred procedure adopted by IUPAC now although such names can be accepted as IUPAC names. The locant should appear before the suffix, not before root word. (ii) The longest carbon chain is found first in such a direction that the double bond remains as a part of the chain . The structure may have a longer chain than this when C=C is excluded, but that does not give the correct longest chain.(This is according to old IUPAC rule. Refer the new rules given later) (iii) The direction of the numbering of the longest chain should be such that the locant of the ene should be minimum. The numbering of the chain is done from one terminal carbon to the other terminal carbon in the direction in which the double bond appears first. The proper direction of numbering the longest chain can be determined by mere inspection. Look at this example.

1

5CH2 4 2 (2-ethyl-3-methylpent-1-ene) H3C C CH2 4 3 2 5 CH2 CH (not 4-ethyl-3-methylpent-4-ene) Example: 3 CH3 1 CH3

Note that in the first name, the locant of ene is 1(pent-1-ene) while in the second, it is 4 (pent-4-ene). According to rule, the locant of ene should be minimum irrespective of the locants of the sustituents. You also noted that the longest carbon chain would have been hexane if we would not have taken the double bond in the main chain. But according to old rule, the double bond should be a part of the main chain. In otherwords, we have to trace out the longest chain while taking the double bond in it. (This is true according to old rule. The new rules are however different. This will be discussed later). Note also that instead of trying with two numbering directions(forward and backward), we can choose the correct direction by mere inspection. The direction in which the double bond appears first gives the correct direction. (iv) If the locant of ene becomes same on both the directions of numbering, then lowest locant or lowest set of locants rule for the substituents is applied to find the correct name. Look at this exampe. Nomenclature of Organic Compounds

CH3 2 4 6 (2-methylhex-3-ene) CH CH CH3 Example 1 3 5 1 5 3 (not 5-methylhex-3-ene H3C CH CH2 6 4 2 In the above case, the locant of ene is 3 on either side(hex-3-ene) and in this case the correct name will be decided by the lower locant(or lowest set of locants)of the substituent(s). In this case 2-methyl is lower than 5-methyl, hence 2-methylhex-3-ene is correct. SAQ II.6: Write the IUPAC names of the following alkenes.

H3C CH3 CH3 H3CCHC CH3 (i) (ii) CH C CH CH 3 H3C

CH2 H3C CH CH3 CH3 (iii) CH CH CH2 CH3 (iv) H3CC C CH2 CH3 H3C

CH3

CH CH CH3 H2CC CH3 (v) H3C C CH (vi) CH3 CH3 CH3

SAQ II.7: Write the structure from the following names. (i) 4-methylhex-1-ene (ii)2-methylbut-2-ene (iii)3,3-dimethylpent-1-ene

SAQ II.8: Some incorrect names are given below. Write their structures and give the correct IUPAC names. (i)2-methylpent-3-ene (ii)2-methylprop-2-ene (iii)3-methylbut-2-ene SAQ II.9: Write the IUPAC names of the alkenes from the line structures.

(i) (ii) Concepts in Chemistry

(iii) (iv)

(v)

ALKYNES The rules for naming alkynes are same as for alkenes excepting that we shall write the suffix yne in place of ene. Yne has its locant and that should be minimum irrespective of the locants of the substituents. In case the locant of yne becomes same on both the directions, then the lower locant or lowest set of the locants for the substituent(s) decides the correct name. Look to the following examples.

CH3 1 2 3 4 HC C C CH 3 3,3-dimethylbut-1-yne (not 2,2-dimethylbut-3-yne) CH3

6 CH CH3 3 4 3 5 2 1 2,2,5-trimethylhex-3-yne CH CCC CH3 NOT 2,5,5-trimethylhex-3-yne

CH3 CH3

SAQ II.10: Write the structures of the following alkynes. (i)pent-1-yne (ii) but-2-yne (iii) 4-methylpent-2-yne SAQ II.11: Some wrong names are given below. Draw the structure from them and write their correct names. (i)pent-3-yne (ii) 5,5-dimethyl-3-hexyne SAQ II.12: Write the IUPAC names from the following line structures. Nomenclature of Organic Compounds

(i) (ii)

ALKENYL AND ALKYNYL GROUPS Alkenyl group: When one H atom is removed from an alkene, an alkenyl group resuts. The last letter e of alkene is replaced by -yl to form this group. This is similar to the formation of alkyl group by the removal of ane H atom from alkane. Alkenyl group is a univalent like alkyl group. The naming is done in the same way as complex alkyl group discussed before.. There are two positon identifiers; one for en and other for yl. The position identifier of yl should be the lowest while that of en is considered after the locant of -yl.. The locant of the first carbon atom of the double bond is the position identifier of the en. Note that the last letter e of ene is dropped because it is facing yl as y is taken to be a vowel for nomenclature. The position identifiers are written before en and yl respectively. When the position identifer of yl is 1 , it is often dropped. In case the alkenyl group is itself branched, then the branch position identifers(locants) appear before alkenyl. For ethenyl(vinyl) postion identifier of ene(i.e 1) is not written. See these examples.

1 3 2 1 3 2 1 CH2 CH CH2 CH CH2 CH3 CH CH ethenyl or vinyl prop-2-en-1-yl or allyl prop-1-en-1-yl or prop-2-enyl or prop-1-enyl

3 2 5 4 3 2 CH3 C CH3 CH CH CH

1CH2 1CH3 prop-1-en-2-yl but-3-en-2-yl

For a two-carbon atom chain, the numbering is not done.. Note that like alkyl group, alkenyl group is univalent. SAQ II.13: Give the names of the following alkenyl groups.

CH3 CH CH2 CH CH (i) CH (ii) 2 2 CH CH2 CH2

CH3

H3C C CH2 (iii) CH CH

CH3 Concepts in Chemistry

Alkynyl group: When one H atom is removed from alkyne, an alknynyl group results. Like alkyl and alkenyl groups, the last letter e of alkyne is replaced by -yl to name this group. The naming is done in the same manner as we have done for alkenyl group. It is also a univalent group.

HC C HC C CH2 H3CC C ethynyl prop-2-yn-1-yl prop-1-yn-1-yl or prop-2-ynyl or prop-1-ynyl SAQ II.14: Name the following groups.

HC C CH2 CH (i) H3CCCCH2 (ii) CH3 BIVALENT GROUPS DERIVED FROM UNIVALENT ALKYL, ALKENYL AND ALKYNYL GROUPS: Bivalent groups can be derived from an univalent alkyl(or alkanyl), alkenyl or alkynyl ≡ groups (R-CH2-, R-CH=CH-CH2- or R-C C-CH2- )by removing one H atom from the carbon atom linked with the principal carbon chain and making it double bond. (eg. R-CH=, R- CH=CH-CH=, R-C≡C-CH=). This becomes a bivalent group. In all other groups, the name of the bivalent group is obtained by suffixing 'idene' to the alkyl(or alkanyl), alkenyl or alkynyl group. alkyl - alkylidene alkenyl - alkenylidene alkynyl - alkynylidene

CH3- (methyl group) CH2= (methylidene group)

CH3-CH2-(ethyl) CH3CH= (ethylidene)

CH3-CH2-CH2-(propyl) CH3-CH2-CH= (propylidene)

H3C H3C CH (propan-2-yl) C (propan-2-ylidene) H3C H3C

H3C CH CH CH (but-2-enyl) H3C CH CH CH (but-2-enylidene)

SAQ II.15 : Write the names of the following groups.

H3C CH3 CH2 CH C CH CH CH2 CH (i) (ii) (iii) H3CC CCH CH3 H3C

H C CH3 H CCCH 3 3 CH CCCH2 (iv) (v) (vi) H2CCCH CH2 (vii)CH =C= CH3 H C 2 3 CH3

(viii) CH3CH(CH3)CH(CH3)CH= (ix) CH3CH2C(CH3)= NEW IUPAC RECOMMENDATIONS FOR NAMING ALKENES AND ALKYNES: Nomenclature of Organic Compounds

In January 2002, IUPAC has provisionally recommended the following new rules for naming alkenes and alkynes. These new rules are given below. The students are advised to use these rules with utmost caution depending upon the requirement since this rule has not yet been introduced in many of text and reference books. (i) The longest continuous carbon chain is found for the compound irrespective of whether it contains the C=C(double bond) or CC(triple bond) or not. In otherwords, the double or triple bond(s) may be excluded to determine the longest chain if situation arises. In such a case, when the double or triple bonds are excluded, the parent compound no longer becomes an alkene or alkyne, instead it becomes an alkane. The branch containing the multiple bond becomes one from alkenyl, alkynyl, alkylidene, alkenylidene or alkynylidene group which is used as prefix. (ii) If two longest chains having same length, one including C-C multiple bond and the other excluding it compete, then the chain including the multiple bonds is considered as the correct longest chain(same as old rule). (iii) In case the longest chain does not include the multiple bond, then the lowest set of locants rule for branches is followed to choose the direction of numbering the longest chain. The branch containing the double or triple bond does not get any preference as functional group. See these examples. 8 6 4 2 CH3 7 5 3 H3C CH3 9 1 2 4 6 8

3 5 7 1 H3C CH3 1 9 2 CH CH2 3 2-methyl-7-methylidenenonane(new name) 5-(prop-2-ynyl)nonane( new name) 2-ethyl-7-methyloct-1-ene(old name) 4-butyloct-1-yne(old name) In the first example, the longest carbon chain is C-9, so the parent compound is nonane. The carbon chain carrying the C=C would have been C-8. But the new rule takes C-9 as the longest chain. The bivalent branch at C-7 position is methylidene. Note that this group does not get any priority over the other methyl group. The lowest set of locant rule gives the locant 2 to

CH3 group and 7 to =CH2 group.(Note that methylidene was previously called methylene) In the second example, the longest carbon chain is C-9. The triple bond is excluded from the main chain. The branch containing the triple bond becomes an alkynyl group(prop-2- ynyl) attached to C-5 of the parent compound nonane.

SAQ 16: Write the names of names of the following alkenes and alkynes on the basis of the new rules. Compare the names with those obtained by using old rules.

CH3 CH3

CH3 CH3 H C (i) H3C CH3 (ii) 3

CH3 CH3 CH 3 H3C Concepts in Chemistry

H3C

CH3 (iii) CH CH3

HALOALKANE(R-X): (i) X can be F, Cl, Br or I and R can be any alkyl group or carbon chain. The rules for naming a haloalkane is analogous to the rules applied to alkanes. Look to this example.

4 3 2 1 H3CCH2 CH CH3 1 2 3 4 (2-bromobutane not 3-bromobutane) Br Besides halogen, if there are other alkyl substituents, then the lower set of the locants rule is applied. Look to this example.

1 2 3 4 5 H3CCHCHCH2 CH3 : 3-bromo-2-methylpentane(not 3-bromo-4-methylpentane) CH3 Br Then alphabetically the substituents are arranged. The correct name is: 3-bromo-2-methylpentane. (Note that halo group(X) does not have a priority like 'ene' and 'yne' groups. Halo group is merely a branch like an alkyl branch while 'ene' and 'yne' are functional groups) (ii) If the longest carbon chain of a haloalkane does not directly bond with halo(X) group, then the halogen becomes a part of a complex branch. The rules for naming a complex branch will be followed for that. See this example.

Br H3C

6 4

H3C 5 3 7 CH3 CH 3 2

H3C CH3 1 4-(2-bromoethyl)-3-ethyl-2,5,6-trimethylheptane Here the longest chain is C-7. So the part containing Br becomes a complex substitutent named as 2'-bromoethyl which is attached to C-4 of the longest chain. If the chain directly bonded to Br would have been considered the number of carbon atoms in the longest chain bearing Br would have been 6. Since this is not the true longest chain, it is not considered. Note that in the above example the sets of locants on both the opposite directions of the longest chain are same. The direction of numbering has been decided on the basis of alphabetical priority of ethyl group over methyl group at C-3 positions on the two opposite directions. Nomenclature of Organic Compounds

SAQ II.17: Write the structure of the following: (i) 2-chloropentane (ii)2-iodopropane (iii)3-chloro-2-methylhexane (iv)2-bromo-3-ethylhexane (v) 1-chlorobutane SAQ II.18 : Some wrong names are given below. Write the structures from them and give the correct names. (i)3-chlorobutane (ii)3-chloro-4-methylpentane SAQ II.19: Give the IUPAC names from the following line structures

ClCH3 Br (i) (ii) (iii) Cl H3C CH3 I ALCOHOLS: (i) First the longest chain is found out in such a direction that the OH group remains directly attached to the longest carbon chain. (ii) The alcohol group(-OH) has a locant. The carbon number to which the OH group is attached is the locant of -ol. The locant is written before the suffix -ol of the alkanol. For example: pentan-2-ol, butan-1-ol etc. (not 2-pentanol, 1-butanol) (iii) The direction of the longest chain should be such that the locant of the ol is minimum. (iv) In case the locants of the ol become same on both the sides, then lower locant or lowest set of the locants for the substituents gives the correct name. OH 3 1 2 4 butan-2-ol (not butan-3-ol) H3CCHCH2 CH3 4 3 2 1

OH CH3 1 2 3 4 5 4-methylpentan-2-ol (not 2-methylpentan-4-ol) H3CCHCH2 CH CH3

OH 5 3 2,2,4-trimethylpentan-3-ol (correct) 4 2 1 2,4,4-trimethylpentan-3-ol(wrong)

In the last example given above, the locant of -ol is same on either side (3) and in such a case the lowest set of locants rule(2,2, 4 not 2,4,4) comes into force.

SAQ II.20: Write the structures of the following: (i)butan-1-ol (ii)2-methylpentan-3-ol (iii)propan-1-ol (iv)propan-2-ol SAQ II.21: Some wrong names are given below. Write structures and give correct names. (i) 2-methylbutan-3-ol (ii)4-methylpentan-3-ol Concepts in Chemistry

SAQ II.22: Write the IUPAC names of the following alcohols.

OH

(i) (ii)

OH

THIOALCOHOLS R-SH is called thioalcohol; the O atom in alcohol(R-OH) is replaced by S atom to make thioalcohol. IUPAC NAME: alkanethiol The letter e of alkane is not dropped because it is facing a consonant(t) in the suffix thiol. Since -SH(thiol) is a functional group, all the rules applicable to alcohols(R-OH) are applicable for thioalcohols(R-SH).

SH CH -SH (methanethiol) CH CH SH (ethanethiol) (butane-2-thiol) 3 3 2 CH3 CH CH2 CH3 SALT OF ALCOHOLS AND THIOALCOHOLS R-O-(alkoxy) and R-S-(alkylsulfanyl or alkylthio) are monovalent groups obtained by removing the H atom from -OH and -SH groups respectively in alcohols and thioalcohols. When a strong metal like Na or K remains bonded with the above mentioned group, a salt results. For example, R-O- Na+ and R-S- K+ are ionic compounds and are shown with + and - signs. These salts are obtained by treating the metal Na or K with the corresponding alcohol or thioalcohol. IUPAC NAMING: Salt of alcohol: RONa - sodium alkan-x-olate (where x is the locant of ol) Salt of thioalcohol: RSNa - sodium alkane-x-thiolate(where x is the locant of thiol) -ate is suffixed to -ol or -thiol to make the suffixes -olate or -thiolate respectively.

1 H3C 3 O Na (sodium propan-1-olate) 2

SNa (potassium ethanolate) (sodium propane-2-thiolate) H3C OK H C 3 CH3 KETONES: (i) The ketone(alkanone) has its locant. The numeral of the carbonyl carbon(C=O) is the locant of the alkanone and is placed before the suffix -one e.g pentan-2-one, hexan- 3-one etc. (ii) The longest chain should carry the carbonyl carbon and the direction of the longest chain should be such that the locant of the -one should be minimum irrespective of the locants of the substituents. (iii) In case the locant of the one becomes same on both the sides, then the lower locant or lowest set of locants for the substituents will decide the correct name. Nomenclature of Organic Compounds

Example :

O pentan-2-one (because carbonyl carbon has the locant 2)) H3CCCH2 CH2 CH3 1 2 3 4 5 Example:

OCH3 2 CH 4C 6CH 1 2 3 5 7 6 4 2 H3C CH 3CH CH3 7 5 1 CH3 CH3 3,5,6-trimethylheptan-4-one (wrong) 2,3,5-trimethylheptan-4-one(correct) In this case the locant of -one is same(4) on both the directions. Hence, the lowest set of locants(2,3,5) gives the correct name. SAQ II.23: Give the structure of the following: (i)propan-2-one (ii)butan-2-one (iii)3-methylbutan-2-one

SAQ II.24: (a)Some wrong names are given. Write their structures and correct the names. (i)butan-3-one (ii)4,4-dimethylpentan-3-one (b)Draw the structural formula for the following (i)potassium 3-methylbutan-2-olate (ii)sodium methanethiolate (iii)3-methylpentane-2-thiol

SAQ II.25: Give the IUPAC name of the following ketones.

O

SH CH3

(i) (ii) (iii) CH3 H3C O ALDEHYDES: (i) The aldehydic carbon always gets number 1 while numbering the longest chain, since it is the terminal carbon atom as well as a functional group. (ii) As usual, the substituents with their locants are written first followed by the name of the parent alkanal. Here the lowest set of the locants rule is not applicable. Hence the numbering of the carbon chain cannot be reversed in this case as we did for other cases before. Only branching rule is followed if more than one longest chain appears in different directions. Concepts in Chemistry

CH3 O (3-methylbutanal) H3CCHCH2 CH 4 3 2 1 Note that the locant of -al(aldehyde group) is always 1 by rule. So, the locant 1 is not written before al. Therefore we write butanal instead of butan-1-al. SAQ II.26: Write the structures of the aldehydes from the following names. (i)2,3-dimethylpentanal (ii)2-ethyl-3-methylhexanal (iii)2-methylpropanal SAQ II.27: Write the structures of the aldheyde from the incorrect names given. Give the correct names also. (i)2-methylbutanl-4-al (ii)2-ethylpropanal SAQ II.28: Write the IUPAC names of the following aldehydes.

H O O

H (i) (ii)

CARBOXYLIC ACIDS(FATTY ACIDS) (i) Carboxyl carbon is always numbered 1 like aldehyde and then longest carbon chain is found. The substituents are written first followed by the name of the alkanoic acid. The locant 1 for the -oic acid is not usually written(e.g butanoic acid, not butan-1-oic acid).

4 CH3 3CH O 2 (2-methylbutanoic acid) H C CH C OH 3 2 1

CH3 6 O CH2 CH3 1 CH3 5 C 2 3CH 4 CH2 HO C CH (2,3-diethyl-2,4-dimethylhexanoic acid) CH3 CH2 CH3 SAQ II.29: Write the structures of the following carboxylic acids. (i) 2,3,3-trimethylpentanoic acid (ii)2-methylpropanoic acid SAQ II.30: Write the IUPAC names of the following carboxylic acids. Nomenclature of Organic Compounds

CH2 O CH CH3 CH3 2 CH OH 2 CH CH2 CH3 (i) CH CH CH2 (ii) C CH3 O OH

(Note that for branched aldehydes and carboxylic acids the names propionaldehyde/propionic acid and butyraldehyde/butyric acid are not used. In stead their systematic names propanal/propanoic acid and butanal/butanoic acid are used).

DERIVATIVES OF CARBOXYLIC ACIDS Carboxyl carbon( C=O) atom in all the derivatives of carboxylic acids is always numbered 1. While finding for longest chain only branching rule is followed. (a)ESTERS:(alkyl alkanoate)

O An ester contains two parts i.e (a)carboxylic acid part ( RC ) and (b)alcohol part (-OR'). (i) The longest chain is numbered in the carboxyl part starting from the carboxyl carbon which is numbered 1. The alcohol(-OR') part is separately numbered only when it is required. (ii) The alkyl group of the alcohol part is written first. This is followed by a space. Then the substituents of the carboxylic acid part with their locants are written in alphabetical order which are followed by the the term alkanoate. No space is given in between the name of the last substituent and the parent alkanoate. (iii) Since locant of -oate is always 1, it is not used before the suffix oate.

H3C 5 CH 4 2 O

CH C CH2 3 1 (ethyl 2,3-dimethylpentanoate) H3C CH O CH3 2 CH3

CH3 O CH3 4 3 CH C 3 CH 1 2 (propany-2-yl 3,3-dimethylbutanoate) H C O 3 CH2 CH3 Note that in the second example, the alkyl group belonging to alcohol part(OR') is propan-2-yl. This alkyl group is to be written first and this is followed by the branches of the alkanoate part(carboxylic part) and finally the term alkanoate. Concepts in Chemistry

SAQ II 31: Draw the structures of the following (i)methyl 3-methylhexanoate (ii)ethyl 2-ethyl-2,3-dimethylbutanoate SAQ II 32: Write the IUAC names of the following

CH3 CH3 CH2 CH OO CH3 C CH2 O CH (i) CH3 CH (ii) (iii) CH O 2 CH CH3 CH O O CH3 CH3

CH3 OCH3 o OCH3

CH3 (iv) (v) O

CH3 CH3 (b) ACID AMIDES: Carboxamide carbon is numbered 1 for assigning the longest chain as usual. The locant of amide(1) is not written. For example, hexanamide not hexan-1-amide.

O 1 C CH3 2 NH CH CH 2 0 3 5 3-methyl-2-propan-2-ylpentanamide(1 amide) CH3 CH 4 CH3 CH3 CH2

TYPES OF AMIDES(Primary(10), secondary(20) and tertiary(30) amides:

O O O R'

RC NH2 RCNH R' RCN 0 00 1 2 3 R'' alkanamide N-alkylalkanamide N-alkyl-N-alkylalkanamide or N, N-dialkylalkanamide There are three types of amides-primary(10), secondary(20) and tertiary(30). If N atom 0 0 is unsubstituted, it is 1 (- CONH2)and if it is substituted by one alkyl group(-CONHR') it is 2 0 0 0 0 and if it is substituted by two alkyl groups(-CONR'2 it is 3 acid amide. 1 , 2 and 3 amides are Nomenclature of Organic Compounds respectively named as alkanamide, N-alkylalkanamide, N-alkyl-N-alkylalkanamide(or N,N- dialkylalkanamide). N-alkyl(s) as well as other branches in the main carbon chain are arranged in alphabetical order. The letter N stands for nitrogen and that is not considered for alphabetical ordering. The example given before is a 10 amide. Examples:

CH3 O CH3 3-methyl-N-(propan-2-yl)butanamide (20 amide) CH3 CH CH2 C NH CH CH3

H3C H3C

CH3 N

3 CH3 1 O 2 4 0 CH3 5 (3 amide)

CH3 6 N-(sec-butyl)-N-ethyl-2,4-dimethylhexanamide N-(butan-2-yl)-N-ethyl-2,4-dimethylhexanamide (PIN) 5

4 6 O 3 1 3-isopropyl-N,N,2,4-tetramethylhexanamide CH3 C 2 (30 amide) N

CH3 N,N,2,4-tetramethyl-3-(propan-2-yl)hexanamide(PIN) Note that the locants N, N were also grouped with 2,4 because all the substitents are identical(methyl). In such case the locant N appears before other numeric locants. (c) ACID HALIDES(ACID CHLORIDES) Rules for naming acid halides(alkanoyl halides) are same as for other derivative. The locant for the -oyl choride(1) is not written. CH 3 O CH 1 2 2 Cl CH 2-ethyl-3-methylpentanoyl chloride 5 3 CH3 4 CH CH2 CH3 (d) SALT OF CARBOXYLIC ACID: This is analgous to esters excepting that the alkyl group of the -OR part is replaced by a metal. O ONa 6 1 5 2 4 3 sodium 4,4-dimethyl-2-(propan-2-yl)hexanoate

Note that there should be a space after the name of the metal. For divalent metal like Ca or trivalent metal like Al, there would be two and three alkanoate parts respectively. Concepts in Chemistry

(e) ACID ANHYDRIDE Rules are same as for other derivates. For symmetrical acid anhydride only one acid part is named(substituents in alphabetic order come first followed by alkanoic anhydride).

O O 3-methylbutanoic anhydride (symmetrical anhydride) 3 1 O 4 2 For unsymmetrical or mixed anydride, naming has to be done two times separately for each of the two acid parts. The branches in alphabetic order are to be placed before the respective alkanoic parts and the alphabetic ordering of the two units are done on the basis of the first letter(see below). The two parts are to be separated by a space and there is no space in between the names of substituents and the term alkanoic in each part. A space is to given before anhydride as usual.

CH3 CH3

4 2 O 2 3 1 1 3,4-dimethylpentanoic 2-methylpropanoic anhydride H3C CH3 5 3 (unsymmetrical anhydride)

CH3 O O Alphabetical ordering of alkanoic parts: Each alkanoic part alongwith its substituents forms a unit. The first letter of each unit is considered for alphabetical ording of two units. While prefixing the substituents to each alkanoic part, the multiplying prefix di, tri, tetra etc.are not considered for ordering the substituents but while ordering the two alkanoic units(inclusive of substituents) di, tri, tetra etc. are considered. Look at this example.

CH3 H 3C CH3

H 3 C O

CH3 H 3C O O CH3 2,2-dimethylpropanoic 2-ethyl-3,3-dimethylbutanoic anhydride Note that while ordering the substituents of butanoic part ethyl comes before dimethyl. Here di- is not considered. But while making alphabetical ordering between two units, d of dimethylpropanoic gets precedence over e of 2-ethyl-3,3-dimethylbutanoic. (f) ALKANENITRILE Cyanide(CN) carbon is always numbered 1 and other rules are same as for other derivatives. The locant of nitrile(1) is not written.

5 4 CH3 CH 2 CH3 3 2,3-diethylpentanenitrile CH3 CH 2 CH2 CH2 CH

1 C N Note that the last letter e of alkane is not deleted here as nitrile begins with a consonant n. Note that a vowel in the root name cannot face another vowel in the suffix. Similarly, a consonant in the root name cannot face another consonant in the suffix. A vowel will always face a consonant. Nomenclature of Organic Compounds

SAQ II 33 : Write down the IUPAC names of the following from their line structures.

O (i) (ii) O O O NH2

O

Cl

(iii) (iv) Na O

O

CH3 O CH3

NH CH3 (v) (vi) H3C CH3

CN CH3

SAQ II 34: Draw the structures from the following names. (i)calcium 2,3,3-trimethylhexanoate (ii)2-ethylpentanoic anhydride (iii)2-(butan-2-yl)-3-methylhexanenitrile (iv)N,2-bis(propan-2-yl)pentanamide

AMINES The naming is analogous to alcohols. The carbon atom bearing the N atom gives the locant of amine. The direction of numbering the longest chain should be such that the amine gets the lowest locant. If the amine gets the same locant on both the directions, then lowest set of locants rule for the substituents holds good. If the set of locants also become same, then alphabetical priority is considered for numbering. Note that as for an alcohol, the longest carbon chain should bear N atom of an amine. 10 amine(prim. amine)

1 5 3 4 2 Example: NH2 3-ethyl-2-(propan-2-yl)pentan-1-amine

Note that in this case the locant of amine is 1 and that should be written before the suffix amine. Concepts in Chemistry Caution: If the locant of the amine is not written then the naming becomes incorrect.

5 4 1 3 3-ethyl-4-methylpentan-2-amine Example: 2

NH2

Caution: Note that the C-2 to which NH2 group is attached is not a terminal carbon. Hence it cannot be numbered as C-1. 20 amine(sec-amine) In 20 amine, N is connected with two alkyl groups(same or different). The alkyl group containing longer continuous carbon chain from terminal to terminal becomes the parent alkanamine and the other becomes an alkyl substituent to the N atom( called N-alkyl). If both the alkyl groups have identical length , then the one which gives lower locant to amine function gives the correct longest chain. If the locant of amine is same on both alkyl parts, then the alkyl part which is more branched gives the correct longest chain. If the number of branches are also same alongwith locant of the amine, then lower set of locants for the substituents decides the correct name parent amine.

CH3 H3C CH3 3' 1' HN 4' CH 2' CH3 4 6 CH3 CH 5 3 CH3 2 4 7 1 CH3 NH 3 CH 2 CH2 3 H3C CH3 CH2 1 CH2

2,5-dimethyl-N-(propan-2-yl)heptan-4-amine N-(3-methylbutan-2-yl)butan-1-amine In the first example, the alkyl group having 7 carbon atoms in the main chain becomes the parent alkanamine. Again the locant of amine is same(4) from both the sides. So the lower set of locants is considered to choose the correct direction of numbering. Note that the alkyl group (R-) attached to nitrogen atom has N as its locant. In the second example, both the alkyl groups attached to NH function contains 4 carbon atoms in the longest chain. In that case, the chain giving lower locant to amine(1-amine) is taken as the parent alkanamine. Note that the other alkyl group is more branched, but it is not taken for the parent alkanamine as it gives higher locant (2) to amine. Note that the locant N can also be used along with other numeric locants if identical branches appear in carbon atoms as well as in N atom of amine group. See this example. 1 6 2 4 3 5 7 N,5-diethyl-4-isopropyl-3-methylheptan-2-amine NH

N,5-dimethyl-3-methyl-4-(propan-2-yl)heptan-2-amine Nomenclature of Organic Compounds

Alternative of 20 Amine: (this is similar to trivial system) alkyl(alkanyl) alkyl(alkanyl) amine or dialkyl or bis(alkanyl) amine Alternative name of the 1st example: (2,5-dimethylheptan-4-yl)(propan-2-yl)amine Althernative name of the 2nd example: butyl(3-methylbutan-2-yl)amine 30 Amines(tert-amines): In 30 amine, three alkyl groups are attached to N atom. The alkyl group which has the longest continuous carbon chain from terminal to terminal is taken as the parent alkanamine and the other two alkyl groups become substituents of N atom(N-alkyl-N-alkyl or N,N-dialkyl). If the alkyl groups have the same chain length, then same principles are followed as explained in 20 amine.

CH3 CH3

CH3 N

CH3 N-(butan-2-yl)-N-ethyl-4,4-dimethylhexan-3-amine

H C CH3 3 CH3 The two alkyl groups attached with N atom are ethyl and sec-butyl. In place of sec-butyl you can write 1-methylpropyl. But the use of sec-butyl is preferred. Alternative Name of 30 Amine: alkylalkylalkylamine, dialkylalkylamine or trialkylamine Alternative name of the above example: ethyl(butan-2-yl)(4,4-dimethylhexan-3-yl)amine SAQ II.35: Write the IUPAC names of the following line structures.

NH2

(i) (ii) N

N (iii) NH (iv) Concepts in Chemistry

CH3 CH H3C H3C 3 CH3 CH3 H3C H3C (v) HN (vi) HN CH3 CH3 CH3 CH3

SAQ II.36: Draw the structures from the following names (i)2,3,4-trimethylpentan-3-amine (ii)N,N-bis(butan-2-yl)-2,3-dimethylpentan-3-amine (iii) N,4,4,5-tetramethylhexan-3-amine ETHERS: (alkoxyalkane/alkyloxyalkane) (i) R-O- goup is called alkoxy or alkyloxy .

For methyl, ethyl, propyl and butyl, the last letter 'yl' is replaced by 'oxy'. CH3O-(methoxy), CH3CH2O-(ethoxy), CH3CH2CH2O-(propoxy), CH3CH2CH2CH2O-(butoxy). From pentyl onwards, the letters 'yl' are not replaced. In stead 'oxy' is suffixed after alkyl.

CH3CH2CH2CH2CH2O-(pentyloxy), follwed by hexyloxy and so on. In other words, when the locant of 'yl' is 1, then 'yl' is replaced by 'oxy' uptill butyl, thereafter it is not replaced. However the locant 1 is dropped in higher alkyloxy names. (ii) When the locant of -yl- is not 1, in that case 'oxy' is suffixed to 'alkanyl'. For example

CH3-CH(CH3)-O- is propan-2-yloxy. Similarly butan-2-yloxy and so on. (iii) The group RO- has no priority as a functional group. It is analogous to any alkyl group(R) while following the lowest set of locants rule for choosing the correct direction of numbering. In otherwords, locant of alkoxy may not necessarily be minimum as it competes with other alkyl groups for getting its locant. (iv) Out of the two alkyl groups attached to O atom, the one having longer continuous carbon chain from terminal to terminal gives the name of the parent alkane. The other alkyl group coupled with O atom forms the alkoxy/alkyloxy/alkanyloxy group. If both the alkyl groups contain the continuous carbon chain of same length, then the chain which is more branched gives the name of the parent alkane. If the alkyl groups have same length and same number of branches then the chain giving a lowest set of locants for the substituents gives the parent name. Note that alkoxy group does not get any special preference in this like amines. Examples:

1 3 5 2 4 6 5 O 4 O 1 3 CH2 2 CH3 4-ethoxy-2,3-dimethylhexane 2,4-dimethyl-3-(propan-2-yl)-1-(propan-2-yloxy)pentane Nomenclature of Organic Compounds

In the first example, methyl group gets lower locant(2) than ethoxy(4). The other direction of numbering would have given the locant 3 to the first branch(ethoxy). So you find that alkoxy group has no priority over alkyl group in the assignment of locants. In the second example, the locant of alkoxy is 1 and the group gets the priority not because it is a functional group but because it agrees with lowest set of locants rule. Examples:

1' 1 1 3 2' 1' 2 4' 4 2 O 2' 3' 5 3 3' O 2-(2-methylbutan-2-yloxy)pentane(correct) 2-methyl-1-(2-methylpropan-2-yloxy)propane(correc 2-methyl-2-(pentan-2-yloxy)butane(wrong) 2-methyl-2-(2-methylpropoxy)propane(wrong) In the first example, the alkyl group having 5 carbon atoms in the longest chain gives the parent alkane. Hence the other alkyl group(2-methylbutan-2-yloxy) forms its corresponding alkanyloxy group. In the second example, the chain lengths and number of branches are same in both the alkyl groups, so that the alkyl group giving the lowest set of locants(1,2) is chosen as the parent alkane. (v) The longest carbon chain to be found out without looking whether alkoxy group is directly linking with it or not. If the longest carbon chain does not directly link with the alkoxy group then it is no longer an alkoxy group rather it becomes a alkoxyalkyl substituent. See this example.

CH3 H3C

CH3 O 4-(ethoxymethyl)-2-methyloctane

H3C In this case the longest chain(8) does not bear O atom. In stead it is attached to a methyl branch which is attached to C-4 of the longest chain. Since one H atom of methyl is substituted by ethoxy group, the whole complex group is called ethoxymethyl.Since it is a complex branch it is placed within parenthesis. Since there is no internal locant in it, the parenthesis may be deleted . SAQ II. 37: Write the IUPAC names for the following line structures.

O (i) (ii) O Concepts in Chemistry

H3C CH3

H3C CH3 H C (iii) O (iv) 3 O CH3

CH3 CH3 CH CH3 3

CH3 O H C O 3 CH (v) (vi) 3 H C 3 CH3 CH3

SAQ II.38: Draw the structures from the following names. (i) 2-methyl-2-(propan-2-yloxy)butane (ii) 2,3-dimethyl-2-(2-methylbutoxy)butane (iii) 2,3-dimethyl-3-(2-methylbutan-2-yloxy)pentane

THIOETHERS: When O atom of ether(R-O-R') is replaced by S, we get thioether(R-S-R') i IUPAC NAME: alkylsulfanylalkane (alkylthioalkane) The alkyl group containing less number of carbon atoms is included with S to make alkylsulfanyl group(like alkoxy group in ether). The alkyl group containing greater number of carbon atoms becomes the parent alkane. Other rules are same as for ethers.

CH3-S-CH2-CH3 (methylsulfanylethane) CH3-S-CH3(methylsulfanylmethane)

CH3 1

2 CH3 2-(ethylsulfanyl)butane 4 3 H3C S

NITROALKANES: Like alkoxy group in ether, nitro group has no priority as functional group. The lowest set of locants rule is the only guiding rule.

6 4 2 7 5 3 1 2,3,4,4-tetramethyl-5-nitroheptane

NO2

In the reverse direction, nitro appears at C-3. That is why the correct direction of numbering is from right to left. Nomenclature of Organic Compounds

SAQ II.39: Write the IUPAC names from the following structures.

CH3 NO 2 S (i) (ii) (iii) H3C CH3 NO2

CYCLOALKANES Hydrocarbons having cyclic or ring structures are called cyclalkanes and have the general formula CnH2n same as the formula for alkenes. The alkane is prefixed with cyclo to give the name of cycloalkane e.g cyclopropane, cyclobutane, cyclopentane and so on. They are also called alicyclic compounds.

CH CH CH 2 CH2 2 2 H2C CH2 H2CCH2 CH2 CH2 CH CH cyclopropane cyclobutane 2 2 cyclopentane

CH2 CH2 CH2

H2C CH2 CH2 CH2

CH2 CH2 CH 2 CH2 CH2 CH2 cyclohexane cycloheptane

The line structures of these cycloalkanes are given below.

cyclopropane cyclobutane cy clopentane cyclohexane cycloheptane

CYCLOALKYL GROUPS: When one H atom is removed from a cycloalkane, a cycloalkyl group results. Note that in each of the above line structures there is one carbon atom at each corner and each carbon atom is attached with 2 H atoms. In line structure, the cycloalkyl group results by putting a dash(-) at any corner in the line structure of cycloalkane.

cyclopropyl cyclobutyl cyclopentyl cyclohexyl cycloheptyl Concepts in Chemistry

Note that the carbon atom bearing the unfulfilled valency(dash) is bearing only one H atom while other carbon atoms are bearing 2 H atoms each. Note that all the carbon atoms are equivalent and a dash can be put anywhere. The formula of cycloalkyl group is CnH2n-1- .

SAQ II.40: Give the names of the following cycloalkyl groups.

H3C CH CH CH2 CH CH2 2 CH CH (i) (ii) (iii) (iv) CH2 CH CH2 CH2 CH2 CH3

Phenyl and benzyl groups: A six membered ring containing alternate single and double bonds is called benzene which has a formula C6H6. Benzene and its derivatives are called aromatic compounds. The discussion on nomenclature of aromatic or other ring compounds will be made in chapter-III.

When one H atom is removed from any carbon atom of benzene, phenyl group(C6H5-) results.

CH2

benzene phenyl group benzyl group In benzene all the six carbon atoms present in the corners bear one H atom each. But in phenyl group the carbon atom attached with the unfulfilled valency(dash) bears no H atom.

Phenyl group is shortly written as C6H5- or Ph- . When one CH2 unit is attached to phenyl, the group is called benzyl. The details on the naming of aromatic compounds will be dicussed in chapter-III. Naming of aliphatic functional compounds containng cyclic rings as branches: Examples:

O O 5 1 3 2 4 O

3,4-dimethyl-1-phenylpentan-1-one isopropyl 4-cyclopropyl-5-methylheptanoate When an aliphatic compound containing a functional group is attached with a ring substituent, it is named as an aliphatic compound with names of the cyclic branches as cyclopropyl, cyclobutyl, phenyl and so on. The detailed rules for naming cyclic compounds are given in chapter-III. SAQ II. 41: Write the IUPAC names of the following Nomenclature of Organic Compounds

H3C OH

CH3 NH (i) (ii) (iii) OCH3

O CH3

H 3 C CH3

CH3 CH2 CH3 H 3 C

CH3

H C CH H3C CH3 3 3 H 3 C

(iv) (v) (vi) CH3

CH3

CH3 EtOOC OH H C CHO 3 CH3 CH3 CH3 CH3

H3C

H C CH (vii) 3 3 (viii) H3C CH3 CH3 CH3 CH3 H2N CH3

CH3 O CH3 H3C

H C H 3 C CH3 3 CH3 H C (ix) 3 CN (x) (xi) H C 3 H 3 C CH3 CH3

CH3 CH3 CH3 CH3

CH3 CH3

H 3 C

H3C CH3 CH3

H 3 C (xii) (xiii) Cl

CH3 CH3 CH 3 O

O CH3

H 3 C

CH3

CH3 H3C CH3 H N CH3

CH3

H3C

N O CH3

(xiv) (xv) CH3

H C 3 H3C

CH3 CH3

CH3 Concepts in Chemistry

H3C CH3

H3C

CH3 O

O Ca (xvi)H3C (xvii) O CH 3 2 O O

Cl CH3 CH3 MeOOC

CH3

CH3 H 3 C H C (xviii) 3 (xix)

CH3

CH3

CH3

H 3C

(xx) (xxi) CH3CH2NC (xxii)CH3CH2NCO H 3C CH 3 O PRACTICE QUESTIONS 1. Write the IUPAC names of the following compounds. Also the class of aliphatic compound to which each of them belongs.

CH3 CH3 CH2 H CCHCH CH3 3 H3CCHCHCH3 (i) (ii) (iii) CH CH3 H CCCHCH 2 3 3 CH H3C 2 Cl

CH3 CH3 CH CH CH C 3 3 H3CC C CCH3 H3CCOH (iv) H3C CH CH3 (v) (vi) CH3 CH3 CH3 OH

CH3 O O CH3 H3CC CH (vii) H3CCCH (viii) (ix) H3CCH2 CH2 Br CH3 CH3

CH2 CH3 O O (x) CH3 CH CH C OH (xi) (xii) CH OH H3CCH2 C OCH2 CH3 3 CH3

O O O (xiii) - + (xiv) H3CCH2 CH2 C O Na H3CCH2 C OCCH2 CH3 O (xv) H3CCH2 NH2 (xvi) (xvii) H3CCH2 CH2 OCH3 H3CCH2 CH2 C Cl Nomenclature of Organic Compounds

O (xviii) (xix) CH -CH -CH -O-N=O H3CCH2 CH2 C NH2 3 2 2 2. Write the structures of the following from the names given below. (i) 2,2,3-trimethylpentane (ii) 4-methylhex-1-ene (iii) 3-methylbutan-2-ol (iv) 2-bromo-3-methylpentane (v) 5-methylhept-1-yne (vi) 3,4-dimethylpentan-2-one (vii) 3-ethyl-2-methylhexanal (viii) 2,2-dimethylpropanoic acid (ix) methylpropanoate (x) calcium ethanoate (xi) ethanoic anhydride (xii) butan-2-amine (xiii) 2-methoxybutane (xiv) propanoyl chloride (xv) butanamide 3. Write the IUPAC names of the following.

H C CH CH3 3 3 CH3 CH3 CH3 H3C H2C OH CH3 CH 3 CH3

CH3 H3C (i) CH3 H (ii) (iii)

H3C H3C CH3

CH3 CH3

O CH3

(iv) (CH3)3CCH(CH3)C(CH3)2CH2COOCH(CH3)CH2CH3 (v)(CH3)2CHCH2NHC(CH3)3

CH3 Cl

CH3 CH3 CH3 CH3 CH3 CH3

H3C H3C CH3 (vi) (vii) (viii)H3C CH3

H3C O O CH3 CH3 H3C

H C O 3 CH CH CH 3 H C 3 3 3 CH3 CH H3C O 3 H3C NH CH3

CH3 CH3 CH3 (ix) H3C (x) (xi) O CH3 H3C CH3 CH3

CH3 CH CH3 3 H3C O Concepts in Chemistry

CH3

CH CH O 3 3 H3C - + CH3 O O K CH3 H C CH 3 3 H3C (xii) (xiii) O (xiv)

H C H3C CH3 CH3 3 Cl

CH3

CH3 CH CH 3 3 H3C CH3 H3C NH2

CH3

H3C CH3 H3C CH3

H3C H3C CH3 (xv) CH3 (xvi) (xvii)

CH3 CH3 CH3

CH3 N H3C CH3

CH3 CH3

(xviii) (CH3)2CHCH(CH3)(CH2)3COOH (xix) [(CH3)2CH]3N (xx) (CH3)3CNO2 4. Draw the structures from the following names. (i) 3,4-bis(propan-2-yl)hept-2-ene (ii) 6-ethyl-7-methyldecan-3-one (iii) 2-(2-methylbutan-2-yl)-3-ethyl-4,4-dimethylpentanal (iv) 4,5-diethyl-3-(pentan-3-yl)heptanoic acid (v) 4-(2-methylbutan-2-yl)-5-ethylhept-2-yne (vi) 2-(butan-2-yl)-3,4,4-trimethylhexan-1-ol (vii) 2-methylpropyl 3,4-diethyl-5-methylhexanoate (viii) 4-methoxymethyl-2-methyloctane (ix) N-(propan-2-yl)-3-methyl-N-(pentan-2-yl)pentan-2-amine (x) N,2,3-trimethyl-N-propylpentanamide (xi) 6-(but-3-ynylidene)dodecane

RESPONSE TO SAQs SAQ II.1 (i) 2,3-dimethylpentane (ii)3-methylpentane

5 CH3 4 CH CH3 3 (iii) H3CC CH3 3,3,4-trimethylpentane(wrong); the set of locants =3,3,4 which is higher 1 2 CH2 CH3 2,3,3-tripmethylpentane(correct) , The set of locants 2,3,3 is lower and is correct.. Nomenclature of Organic Compounds

1 7 CH3 7 CH3 H3C H3C 2 6 CH 6 CH3 3 CH CH CH2 CH2 1 3 3 5 5 (iv) CH (correct); H C 2 CH (wrong) H3C 4 CH 3 4 CH CH2 CH CH2 CH2 CH3 CH2 3 The second one is violating the branching rule. In the first, there are more number of branches attached to the main chain. Count for yourself to verify. Name: 3-ethyl-2,5-dimethylheptane. The reverse direction of numbering would have given a higher set of locants: 5-ethyl- 3,6-dimethylheptane which is wrong.

CH3 1 2 3 H CCCH (v) 3 3 ; 2,2-dimethylpropane (same name if we reverse the numbering) CH3

CH3 CH3 1 2 3 4 H CC CCH (vi) 3 3 ; 2,2,3,3-tetramethylbutane(same name on reverse numbering) CH3 CH3

CH3

8 6 4 2

(vii)H3C 7 5 3 ; 5-methyl-4-propylnonane (reverse numbering would 9 CH3 1

CH3 have given the set of locants 5,6 which is higher) (viii) 5-ethyl-6,7-dimethyl-4-propyldecane (The set of locants are same on either side. Hence lowest locant is given to alphabetically seniormost branch ethyl by numbering from left to right). SAQ.II. 2: While writing the structure of a compound from its name, first look to the word root of the parent alkane. In this case it is alk(e.g pent-, hex-, but- etc.). First draw a carbon chain containing the required number of carbon atoms in straight chain. Let us take the first bit. (i) The parent alkane is pentane. So let us first draw: C-C-C-C-C. Then number them from one end to the other end. Attach the substituents(branches) at the appropriate carbon atoms.

1 2 3 4 5 CCCCC

CH3 CH3 Concepts in Chemistry

Then attach the required number of hydrogen atoms to each carbon atom of the main chain bearing in mind that the valency of carbon is 4.

1 2 3 4 5 CH3 CH CH CH2 CH3

CH3 CH3

2 3 4 5 6 CH3 CH2 CH CH2 CH2 CH3 (ii) CH3

CH3 1 2 3 1 2 3 45 6 CH3 CH CH3 CH3 CCH2 CH CH2 CH (iii) 3 (iv) CH CH3 CH3 3 SAQ II. 3: 4 3 2 1 CH3 CH2 CH CH3 (2-methylbutane) (i) CH3 The locant of the branch should be lower. We have to number from right to left.

1 2 CH3 CH CH3 3 (ii) CH2 (2-methylbutane) The longest chain contains four carbon atoms. 4 CH3

6 5 4 3 2 1 CH3 CH2 CH CH CH CH3 (iii) (2,3-dimethylhexane) If we go from right to left, CH3 CH3 the, set of the locants (2,3) is lower. SAQ II.4: (i) 4-ethyl-2-methyl-5,6-dipropylnonane (ii) 3,6,8-triethyl-2,4-dimethyl-6-propylundecane (iii) 5-(pentan-3-yl)decane (iv) 6-(3-methylbutyl)-5-(2-methylpropyl)undecane (v) 2,3,5-trimethyl-4-propylheptane (vi) 2,5-dimethyl-4-(2-methylpropyl)heptane (vii) 7-(2-methylhexan-2-yl)-7- (2-methylpentan-2-yl)tridecane (viii) 7,7-bis(2,4-dimethylhexyl)-3-ethyl-5,9,11-trimethyltridecane (ix) 6-(octan-4-yl)-5-(propan-2-yl)dodecane (x) 6-ethyl-2,4-dimethyl-5-(2-methylpropyl)-3-(propan-2-yl)octane (xi) 2,3-dimethyl-5-(propan-2-yl)octane Nomenclature of Organic Compounds

(xii) 3,6-dimethyl-5-(3-methylbutan-2-yl)-7-(propan-2-yl)decane (xiii) 4-(2,2-dimethylpropyl)-9-ethyl-2,2-dimethyl-6,6-bis(2-methylpropan-2- yl)undecane (xiv) 6-methyl-5-(3-methylbutan-2-yl)decane

SAQ II.5:

H3C CH3 CH3 H3C H3C

CH (i) 3 (ii)

CH3

CH3 CH3

CH CH3 H3C 3 H3C CH3 CH3 H3C (iii) (iv)H3C CH3 H3C CH3 H3C CH3 CH3

H 3 C CH3

CH3

H 3 C

(v) CH3 H 3 C

CH3

CH3 SAQ II. 6: (i)2-methylbut-2-ene(not 3-methyl-but-2-ene) (ii)3,4-dimethylpent-2-ene(not 2,3-dimethylpent-3-ene)

1 5 2 CH2 H3C CH 3 4 (iii) CH CH CH2 CH3 (3-ethyl-4-methylpent-1-ene)

H3C Note that the longest chain cannot be towards the right side in the above example, although we get the chain of five carbon atoms. If we do so, we shall violate the branching rule. (iv) 2,3-dimethylpent-2-ene (v) 2,3,5-trimethylhex-3-ene(not 2,4,5-trimethylhex-3-ene) In this case, the locant of the ene becomes same(hex-3-ene) on either side, so the lower set of locants rule is valid. In the first case the set of the locants is 2,3,5; while in the second case it is 2,4,5, so the first name is correct. (vi) 2-methylprop-1-ene (or 2-methylpropene) Note that since prop-2-ene is not possible, locant of ene(1) may be deleted. But it is customary to retain the locant. Concepts in Chemistry

SAQ II. 7:

1 2 3 4 CH3 CH3 CCHCH3 (i) 1 2 3 4 5 6 (ii) CH2 CH CH2 CH CH2 CH3 CH3

CH3 1 2 3 4 5 CH2 CH C CH2 CH3 (iii) CH3 SAQ II. 8:

5 4 3 2 1 CH3 CH CH CH CH3 (4-methylpent-2-ene) (i) CH3 In case of alkene, you know that the direction of carbon chain should be such that the locant of the ene(pent-2-ene) should be smaller. 3 2 1 CH3 CCH2 (2-methylprop-1-ene or 2-methylpropene (ii) CH3 4 3 2 1 CH3 CH C CH3 (2-methylbut-2-ene (iii) CH3 You know that if the locant of the ene is same on both the directions(forward and reverse) of numbering, then the one which has lower locant of the branch or satisfies the lowest set of the locants rule gives the correct name. In this case we go from right to left while numbering. SAQ.II.9: (i) 4-ethyl-3,6-dimethyl-5-(propan-2-yl)hept-3-ene (ii) 4,5-dimethyl-3-(2-methylpropyl)hept-1-ene (iii) 4-(butan-2-yl)l-5-(2-methylpropan-2-yl)oct-3-ene (iv) 6-ethyl-3,3-4-trimethyloct-4-ene (v) 6-ethyl-2,8-dimethyl-7-propyldec-5-ene

1 2 3 4 5 SAQ II. 10: (i) HC C CH2 CH2 CH3 (not pent-4-yne) 5 4 3 2 1

1 2 3 4 (ii) H3CC C CH3

CH3 (iii) 1 2 3 4 5 (not 2-methylpent-3-yne) H3CC CCHCH3 SAQ II. 11:. 1 2 3 4 5 (i) H3CCH2 C C CH3 pent-2-yne (the locant of the alkyne should be lower) 5 4 3 2 1 Nomenclature of Organic Compounds

CH3 6 5 4 3 2 1 H CCH CCCCH (ii) 3 2 3 (2,2-dimethylhex-3-yne) CH3 In this case the locant of yne is same on either side(hex-3-yne). In such case the lowest set of the locants rule comes into force. In the correct name, the set of locants of the substituents is 2,2 not 5,5. SAQ.II.12: (i) 6-(butan-2-yl)-3-(propan-2-yl)-2,2,7-trimethylnon-4-yne (ii) 3-ethyl-8-methyldec-5-yne(ethyl gets precedence over methyl due to alphabetical seniority of the former) SAQ.II.13:

4 2 4 2 5 H3C 3 CH 1 CH 3 CH2 1 H C (i) CH2 CH (ii) 2 CH2 CH2 but-1-en-1-yl (but-1-enyl pent-4-en-1-yl (pent-4-enyl

CH 5 3 1 H C 3 3 4 C 2 CH2 CH CH (iii) CH3 2,3-dimethylpent-3-enyl SAQ.II.14: (i) but-2-yn-1-yl (but-2-ynyl) (ii)pent-4-yn-2-yl SAQ.II.15: (i) 3-methylbutylidene (ii)2-methylpent-2-enylidene (iii)but-2-ynylidene (iv)2-methylprop-1-enyl (v)4-methylpent-2-ynyl (vi)2,3-dimethylbut-3-enyl (vii)ethenylidene(vinylidene) (viii) 2,3-dimethylbutylidene (ix) butan-2-ylidene SAQ.II.16: (i) 3,4-diethyl-5-methylhept-2-ene(same according both the rules as the C=C bond is included in the longest chain) (ii) 4-ethyl-2,7-dimethyl-5-propylidenenonane(new); 5-ethyl-7-methyl-4-(2-methylbutyl)oct-3-ene(old) (iii) 3-ethyl-5-ethynyloctane(new); 5-ethyl-3-propylhept-1-yne(old) SAQ II. 17: 1 2 3 4 5 1 2 3 H3CCHCHCH2 2 CH3 H3CCHCH3 (i) (ii) Cl I Concepts in Chemistry

1 2 3 4 5 6 1 2 3 4 5 6 H3CCHCHCH2 CH2 CH3 H3CCHCHCH2 CH2 CH3 (iii) (iv) Br CH2 CH3 Cl CH3

1 2 3 4 (v) Cl CH2 CH2 CH2 CH3

Cl SAQ 18: (i) (2-chlorobutane); H3CCH2 CH CH3

Cl CH3 (ii) (3-chloro-2-methylpentane) H3CCH2 CH CH CH3 SAQ.II.19: (i) 4-(butan-2-yl)-3-chloro-5-methylheptane (ii)4-ethyl-5-iodomethyl-2-methylheptane (iii) 2-bromo-6-chloro-4-methylheptane

4 3 2 1 CH3 OH SAQ.II. 20: (i) H3CCH2 CH2 CH2 OH (ii) H3CCHCHCH2 CH3

1 2 3 (iii) HO H2CCH2 CH3 (note that OH group can be written either at the left terminal or right terminal for the alkan-1-ol)

OH (iv) H3CCHCH3 SAQ.II. 21:

CH3 OH (i) 4 3 2 1 :3-methylbutan-2-ol ( the locant of ol group should be minimum) H3CCHCHCH3

OH CH3 (ii) 5 4 3 2 1 :2-methylpental-3-ol . When the locant of ol(pentan-3-ol) H3CCH2 CH CH CH3 becomes same on either side, the lowest locant of the substituent gives the correct name. SAQ.II.22: (i) 2,3-bis(2-methylpropyl)-4-methylhexan-1-ol (ii) 5-(2-methylbutan-2-yl)-3-ethyl-2-methyloctan-4-ol Nomenclature of Organic Compounds

SAQ.II. 23:

O (i) This is also called propanone(acetone) as the keto group cannot remain in H3CCCH3 terminal(first and last) positions.

O O CH3 (ii) (iii) (not 2-methylbutan-3-one) H3CC CH2 CH3 H3C C CH CH3

SAQ.II. 24:(a) O (i) (butan-2-one) You know that the locant of one should be minimum. H3CCH CCH3 4 3 2 2 1

O CH3

H3CCH2 C CCH3 (ii) 5 4 3 2 1 ; 2,2-dimethylpentan-3-one. When the locant of one becomes CH3 same, the set of the locants of the substituents should be lower. In this case the set (2,2) is lower than the set (4,4). (b) CH 3 SH

3 CH3 4 2 1 2 H C 3 (i)H3C (ii)CH SNa (iii) 3 CH3 4 3 5 1 CH OK 3 SAQ.II.25: (i) 4-ethyl-5-methyl-3-(2-methylpropyl)hexan-2-one (ii) 4-(butan-2-yl)-2,6-dimethylnonan-5-one (iii) 4-methylhexane-2-thiol SAQ.II.26:

CH3 CH3 O (i) H3CCH2 CH CH C H 5 4 3 2 1 Note that for writing the structure of any compound, first the skeleton of carbon chain is drawn looking to the root word of the parent compound such as hex, pent, but etc. and then the functional group is drawn. In this case, the aldehyde group is drawn first by attaching an oxygen atom to the terminal carbon atom with a double bond and attaching a H atom by a single bond. Then carbon chain is numbered. In this case numbering should start from the aldehyde carbon. Then attach the sustituents as required. Finally attach the carbon atoms of the main chain with required number of H atoms making each carbon atom tetravalent. Concepts in Chemistry

CH3 CH3 O CH3 CH2 O (ii) (iii) H CCHCH H3CCH2 CH2 CH CH C H 3 6 5 4 321

CH3 O SAQ.II. 27: (i) 1 2 3 4 (The correct name is 3-methylbutanal H C CH CH C H 3 43 2 1 (Aldehyde carbon is always numbered 1 by rule)

4 CH3 3CH O (ii) 2 (The correct name is 2-methylbutanal as the longest carbon chain H C CH C H 3 2 1 contains four carbon atoms, not 3 carbon atoms given in the question). SAQ II.28: (i) 4-ethyl-2,4,5-trimethyl-3-(propan-2-yl)hexanal (ii) 2-(2-methylpentyl)-3,5-dimethylheptanal SAQ.II.29:

CH3 CH3 O CH3 O H3C CH2 CH C C OH (i) 5 4 3 2 1 (ii) CH3 CH C OH CH3 SAQ.II.30: (i) 3-ethyl-2-(2-methylbutyl)hexanoic acid (ii) 2-ethyl-7-(propan-2-yl)-3,5-dimethyl-4-(2-methylbutyl)decanoic acid. SAQ.II.31:

CH3

CH3 O H3C 2 4 (i) (ii) 3 OEt H3CCH2 CH2 CH CH2 C OCH3 1 32 1 6 5 4 CH3 CH3 O SAQ.II.32: (i) butan-2-yl 2-ethyl-4-methyl-3-(propan-2-yl)hexanoate (ii) 2-methylpropan-2-yl 2,4-dimethyl-2-(propan-2-yl)hexanoate (iii) 2,3-dimethylpentyl 2-methylpropanoate (iv) methyl 2-ethyl-3,4,4-trimethyl-2-(propan-2-yl)pentanoate (v) 3-methylbutan-2-yl 3-methylpentanoate SAQ.II.33: (i) 2-(3-methylbutan-2-yl)-3,4-dimethylpentanamide (ii) 2,3-dimethylbutanoic 2,3,3-trimethylpentanoic anhydride (iii) 4-ethyl-6,7-dimethyl-3-(2-methylbutan-2-yl)octanoyl chloride (iv) sodium 2-ethyl-4-methyl-2-propylpentanoate (v) 3-(butan-2-yl)-4,4-dimethylhexanenitrile (vi) 3-methyl-2-(pentan-2-yl)-N-(propan-2-yl)heptanamide Nomenclature of Organic Compounds

SAQ.II.34:

CH CH CH3 CH3 O 3 3

CH3 CH2 CH2 C CH C O Ca O (i) 2 (ii)H3C CH3 CH3 O O H3C CH3 CH3

CN H3C NH CH3 (iii) (iv)H3C CH3 H C 3 O CH3 SAQ.II.35: (i) 3,7,8-trimethyl-5-(propan-2-yl)lnonan-4-amine (ii) N,5-diethyl-3,7-dimethyl-N-propyloctan-4-amine (iii) 3-ethy-4-methyll-N,2-bis(propan-2-yl)pentan-1-amine (iv) 3-methyl-N-(3-methylbutan-2-yl)-N-(2-methylpropyl)pentan-2-amine (v) N-(3,3-dimethylbutan-2-yl)butan-1-amine (vi) 3,3-dimethyl-N-(2-methylbutan-2-yl)butan-2-amine SAQ.II.36:

CH3 H3C

CH CH3 CH 3 NH2 H C 3 NH CH H3C 3 3

H3C CH3 N CH3 (i) (ii)H3C (iii) H3C CH H3C CH3 CH3 3 CH H3C 3 SAQ.II.37: (i) 2,2,4-trimethyl-3-(2-methylpropoxy)pentane (ii) 2-(propan-2-yloxy)propane (iii) 3-ethyl-3-methyl-2-(3,3-dimethylbutan-2-yloxy)pentane (iv) 4-[2-(butan-2-yloxy)ethyl]-2,5,6-trimethyloctane (v) 5-[2-(propan-2-yloxy)propyl]nonane (vi) 2-butoxy-3-methylbutane SAQ.II.38:

O (i) O (ii) O (iii)

SAQ.II.39: (i) 4-ethyl-3,4-dimethyl-5-nitroheptane (ii) 4-ethyl-3-methyl-4-nitromethylheptane (iii) 2-methylsulfanylpropane SAQ.II.40: (i) cyclopropyl (ii) 3-methylcyclopentyl (iii) cyclohex-2-enyl (iv) 2-methylcyclobutyl Concepts in Chemistry

SAQ.II.41: (i) N-(butan-2-yl)-3-cyclohexyl-4-methylhexan-2-amine (ii) 4-(3-methylcyclopentyl)-3-(propan-2-yl)hexan-2-ol (iii) propan-2-yl- 4-benzyl-3-ethylhexanoate (iv) 3-ethyl-2-(2-methylpropyl)pent-1-ene(old); 5-ethy-2-methyl-4-methylideneheptane(new) (v) ethyl 2,3-diethyl-4-methylpentanoate (vi) 3,4-dimethyl-2-(2-methylpropan-2-yl)pentan-1-ol (vii) 4-ethyl-5-methyl-3-(3-methylbutan-2-yl)hexanal (viii) 6,6-dimethyl5-(propan-2-yl)hept-3-yne (ix) 2-(2,2-dimethylpropyl)-2,3,4-trimethylpentanenitrile (x) 3-methyl-3-(propan-2-yloxy)pentane (xi) 4-5-dimethyl-3-(propan-2-yl)heptan-2-amine (xii) 5-methyl-4-(2-methylpropyl)heptan-3-one (xiii) 3,3-dimethyl-2-(3-methylbutan-2-yl)pentanoyl chloride (xiv) 2,3-dimethyl-N-(2-methylbutan-2-yl)-2-propylpentanamide (xv) N-(butan-2-yl)-2,3-dimethyl-N-(propan-2-yl)butan-2-amine (xvi) 2,3-dimethylbutanoic 2,2-dimethylpropanoic anhydride (xvii) calcium 2,3,4-trimethylpentanoate (xviii) 4-(1-chloroethyl)-5,6-diethyl-3-methyloctane (xix) methyl 3-cyclobutyl-2-ethylpentanoate (xx) 2,3,3-trimethyl-1-phenylbutan-1-one

(xxi) isocyanoethane(ethyl isocyanide) (xxii)isocyanatoethane

ANSWER TO PRACTICE QUESTIONS

1.

(i) 2-methylbut-2-ene(alkene) (ii) 3,4-dimethylhexane(alkane) (iii) 1-chloro-2,3-dimethylbutane(haloalkane) (iv) 2,2,4-trimethylpentan-3-ol(alcohol) (v) 4,4-dimethylpent-2-yne(alkyne) (vi) 2-methylpropan-2-ol(alcohol) (vii) 3-methylbutan-2-one(ketone) (viii) 2,2-dimethylpropanal(aldehyde) (ix) 1-bromopropane(haloalkane) (x) 2,3-dimethylpentanoic acide(carboxylic acid) (xi) ethyl propanoate(ester) (xii) methanol(alcohol) (xiii) sodium butanoate (salt of carboxylic acid) (xiv) propanoic anhydride(acid anhydride) Nomenclature of Organic Compounds

(xv) ethanamine(amine) (xvi) butanoyl chloride(acid chloride) 3 2 1 (xvii) H3CCH2 CH2 OCH3 1-methoxy propane(ether) (xviii) butanamide(acid amide) (xix) propyl nitrite 2.

CH3 CH3 CH H C C CH CH CH 3 (i) 3 2 3 (ii) H2CCHCH2 CH CH2 CH3 CH3

OH CH3 Br CH3 (iii) (iv) H3CCHCHCH3 H3CCHCHCH2 CH3

CH 3 O CH CH CH2 3 3 (v) (vi) H C C CH CH CH HC C CH2 CH CH CH3 3 3

CH O H3C 3 CH2 CH3 O H CCCOH (vii) (viii) 3 H3CCH2 CH2 CH CH C H CH3

O O (ix) (x) CH C O Ca (since the valency of Ca is 2) H3CCH2 C OCH3 3 2

CH3 O O NH2 O (xi) (xii) (xiii) H3CCOC CH3 H3CCHCH2 CH3 1 234 H3CCHCH2 CH3 1 2 3 4

O O (xiv) (xv) CH3 CH2 C Cl H3CCH2 CH2 C NH2 3. (i) 2,3,4-trimethyl-3-(2-methylpropan-2-yl)hexanal (ii) 2,6,7-trimethyl-5-methylidene-4-(propan-2-yl)nonane(new) (iii) 2,4-dimethyl-3-(pentan-2-yl)octan-1-ol (iv) butan-2-yl 3,3,4,5,5-pentamethylhexanoate (v) 2-methyl-N-(2-methylpropan-2-yl)propan-1-amine (vi) 7,9-dimethyl-4-(propan-2-yl)decan-5-one (vii) 5-(1-methoxyethyl)-2-methylnonane Concepts in Chemistry

(viii) 6-(2-chloropropyl)-7-ethyl-2-methylundecane (ix) 2,7,8,8-tetramethyl-6-(propan-2-yl)non-3-yne (x) 4,4,6-trimethyl-N-(2-methylpentan-2-yl)-2-(propan-2-yl)heptanamide (xi) 2,2-dimethylbutanoic 2-ethylbutanoic anhydride (xii) 3-(2-methylpentan-3-yloxy)-2,4-dimethylpentane (xiii) 3-(butan-2-yl)-2,2,5-trimethylheptanoyl chloride (xiv) potassium 4-ethyl-3,6-dimethyl-5-propyloctanoate (xv) 6,9-bis(butan-2-yl)-4-ethyl-11-methyl-7,8-bis(propan-2-yl)tetradecane (xvi) 4-methyl-2-(3-methylbutan-2-yl)-3-(propan-2-yl)heptanenitrile (xvii) 3-ethyl-4-methyl-2-(pentan-3-yl)hexan-1-amine (xviii) 5,6-dimethylheptanoic acid (xix) N,N-bis(propan-2-yl)lpropan-2-amine (xx) 2-methyl-2-nitropropane

CH3 O H 3 C CH3

9 7 5 3 CH3 1 8 6 4 2 H3C 10 4. (i)H 3 C CH3 (ii)

H 3 C CH3 CH3

CH3

CH3 6 4 2 H C CH H3C 3 3 5 3 H3C COOH H3C 7 1 5 4 2 (iiii) (iv) CH H C 3 3 3 CHO H C 1 3 CH3 CH3

H3C CH3 OH CH3 CH3 5 3 1 H3C 4 32CH 3 H3C 4 1 6 2

(v) 65 (vi) H3C H3C CH H3C CH3 3 7

CH 3 O

3 1 CH3

2 4 O (vii) H3C

5 CH3 H3C CH3 6 Nomenclature of Organic Compounds

7 5 3 CH3 1 CH CH3 6 4 2 3 H3C 1 CH3 8 5 2 4

CH3 H3C N 3 (viii) O (ix) 3 1 CH3 2 H3C CH3 CH3 4

CH CH 3 3 CH

4 2 N

3 1 H3C CH3 (x) 5 (xi)

CH3 H C CH3 O 3