Problems and Solutions in Organic Chemistry Is Primar- of Problems Included in Each Chapter Is Given Here

Problems and Solutions in

Organic ChemistryPress

Subrata Sen Gupta Formerly, Reader in Chemistry R.P.M.University College, West Bengal

Oxford

PSOC_FM.indd 1 12/30/2015 5:30:48 PM 3

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PSOC_FM.indd 2 12/30/2015 5:30:49 PM Preface

Though chemical compounds are visible to the naked eye, discussed, students would get specific information on the their constituent atoms and bonds are invisible even under a types of reactions these two different classes of carbonyl very powerful microscope. When one tries to visualize the compounds take part in. Such an approach to learning formation of a compound, one has to depend on the infor- the subject is more pragmatic as it helps readers get mation available in related literature, confirmed through acquainted with the relevant reactions within a class of time-tested experiments. Therefore, when a student comes organic compounds. across a new problem, the solution can only be rationalized as a ‘plausible’ explanation or by concluding that ‘results KEY FEATURES have to be confirmed by experiments and investigations’. • Problems on the nomenclature of the different classes Organic chemistry is a mind-boggling field of chemistry, of organic compounds based on IUPAC rules, and in the sense that nature has produced thousands of organic the answers to these molecules with unimaginable complexities. Fascinated by • A plethora of problems on the classes of compounds this area of study, chemists are observing and following with plausible mechanisms and rationalization, nature to synthesize many new compounds in their labora- where necessaryPress tories, many of which have changed our lifestyle in unim- • Illustrative reaction mechanisms through well-drawn aginable ways. diagrams with supportive explanations and com- Young learners must realize that to excel in any science ments wherever needed course, they must develop the habit of solving problems. • Problems on stereochemistry, spectroscopy, and per- To gain confidence in this, they would initially need the icyclic reactions assistance of books that contain a large number of solved • Over 1500 solved problems addressing various topics problems. It is with this objective in mind that Problems on the subject and Solutions in Organic Chemistry was conceived. The • Includes 700 chapter-end exercise problems to aid book is designed as a self-study material, to expose stu- self-evaluation dents to the various facets of organic chemistry. University CONTENTS AND COVERAGE ABOUT THE BOOK The book has 21 chapters. A short description of the nature Problems and Solutions in Organic Chemistry is primar- of problems included in each chapter is given here. ily written for undergraduate students who have opted for Chapter 1, Nomenclature of Organic Compounds, provides an Honours course in chemistry. It will also be useful for problems on the naming of various aliphatic, alicyclic, aro- students pursuing postgraduation in chemistry and those matic, fused polynuclear, spiro, heterocyclic, and bridged preparing for competitive examinationsOxford such as the Joint compounds. The nomenclature of many unique unsatu- Admission Test for Masters (JAM), National Eligibility rated aliphatic compounds and compounds with a variety Test (CSIR–UGC NET), and Graduate Aptitude Test in of functional groups have been discussed. End-chapter Engineering (GATE). exercises discussing certain interesting chemical structures Most problems in each chapter have been discussed have also been included. on the basis of traditional functional groups present in organic compounds. This will help students get an idea of Chapter 2, Physical Organic Chemistry, deals with prob- the types of problems based on a particular class of com- lems based on the concepts and theories in organic chemis- pounds. For example, alcohols can participate in elimi- try, such as acid–base reactions, dipole moments, reaction nation reactions, etherification reactions, esterification rates, tautomerism, reaction kinetics, and aromaticities. reactions, and are reagents in nucleophilic substitutions Chapter 3, Stereochemistry, includes a large number of as well. Therefore, if we separately discuss the problems problems on various aspects of stereochemistry involving on alcohols, we can get an idea of the different types of organic molecules. Problems on both static and dynamic reactions these compounds take part in. Similarly, the stereochemistry have been demonstrated. properties of aliphatic carbonyl compounds and aromatic carbonyl compounds differ in many reactions. Therefore, Chapter 4, Aliphatic and Alicyclic Hydrocarbons and if problems on these compounds are individually their Halides, elucidates problems on both saturated and

PSOC_FM.indd 3 12/30/2015 5:30:55 PM iv Preface

unsaturated compounds in addition to those on aliphatic Chapter 16, Carbohydrates, has problems dealing with and alicyclic hydrocarbons. naturally occurring typical monosaccharides, disaccha- rides, and polysaccharides. Chapter 5, Alcohols and Ethers, throws light on typical problems on alcohols and aliphatic ethers. Chapter 17, Amino Acids, Proteins, and Nucleic Acids, deals with a variety of problems on important biomole- Chapter 6, Aliphatic Carbonyl Compounds, deals with a cules such as amino acids, proteins, and nucleic acids. wide array of interesting problems on aliphatic aldehydes and ketones. Chapter 18, Molecular Rearrangements, analyses problems associated with molecular rearrangements encom- Chapter 7, Aliphatic Acids and their Derivatives, describes passing all the classes of organic compounds. problems on aliphatic acids and their derivatives, such as esters, amides, and acid halides. Chapter 19, Conversions and Syntheses of Organic Compounds, gives a clear picture on the mechanisms Chapter 8, Aliphatic and Alicyclic Amines, Nitriles, related to conversions among organic molecules and also Isocyanides, Ylides, Diazocompounds, and Organometallic talks about the synthesis of organic molecules from typical Compounds, discusses a host of interesting problems on compounds and reagents. these classes of compounds. Chapter 20, Constitutional Problems on Organic Chapter 9, Aromatic Carbonyl Compounds, explores the Compounds, has a diverse range of problems on the iden- typical problems associated with these compounds. tification of compounds based on a sequence of reactions. Chapter 10, Aromatic Acids, Amines, Nitro-compounds, Chapter 21, Miscellaneous Problems, presents a large num- and Diazo-compounds, comprises a large number of prob- ber of interesting problemsPress based on the different classes of lems on these staggering classes of compounds. organic compounds and a variety of organic reactions we Chapter 11, Phenolic Compounds, Benzoquinones, and encounter in organic chemistry. Aromatic Ethers, deals with specific and interesting prob- Appendix A, Abbreviations of a Few Reagents Used in lems on these compounds to understand their reactions Chemical Literature, lists out the abbreviations and the better. corresponding chemical structures of some frequently used reagents in organic reactions. Chapter 12, Benzenes, Polynuclear and Alicylic Hydrocarbons, explains problems on benzene and substi- Appendix B, Reducing and Oxidizing Agents Commonly tuted benzenes, polynuclear aromatic hydrocarbons, and Used in Organic Chemistry, lays emphasis on the various some additional problems on alicyclic compounds, which reducing and oxidizing agents, along with their chemical have not been discussed in Chapter 4. Universitycomposition, preferred solvent, and reaction mixture. Chapter 13, Pericyclic Reactions, deals with problems on ACKNOWLEDGEMENTS this special class of organic reactions. These include reac- I express my deepest gratitude to Oxford University Press tions such as electrocyclic reaction, cycloaddition reaction, India for accepting this book for publication. I am particu- sigmatropic reaction, and ene-reaction. larly thankful to the members of the editorial team for their Chapter 14, Problems on the Uses of Spectroscopic diligent guidance and cooperation in this endeavour. Methods in Organic ChemistryOxford, illustrates the problems on I also appreciate the support and encouragement I the application of ultraviolet (UV), infrared (IR), nuclear received from my wife, Mrs Arundhati Sen Gupta, and my magnetic resonance (NMR), and mass spectroscopic meth- son, Dr Anirban Sen Gupta, during the preparation of this ods in the identification and determination of structures of book. organic molecules. Suggestions and feedback are welcome and can be sent to me at [email protected] and pushpal314@data- Chapter 15, Heterocyclic Compounds, has a large array of one.in. problems on monocyclic and bicyclic heterocycles with N, O, and S as heteroatoms. Subrata Sen Gupta

PSOC_FM.indd 4 12/30/2015 5:30:55 PM Contents

Preface iii

Features of the Book vi

1. Nomenclature of Organic Compounds 1 2. Physical Organic Chemistry 15 3. Stereochemistry 78 4. Aliphatic and Alicyclic Hydrocarbons and their Halides 144 5. Alcohols and Ethers 168 6. Aliphatic Carbonyl Compounds Press 184 7. Aliphatic Acids and their Derivatives 197 8. Aliphatic and Alicyclic Amines, Nitriles, Isocyanides, Ylides, Diazocompounds, and Organometallic Compounds 216 9. Aromatic Carbonyl Compounds 241 10. Aromatic Acids, Amines, Nitro-compounds, and Diazo-compounds 268 11. Phenolic Compounds, Benzoquinones, and Aromatic Ethers 299 12. Benzenes, Polynuclear and Alicyclic HydrocarbonsUniversity 317 13. Pericyclic Reactions 351 14. Problems on the Uses of Spectroscopic Methods in Organic Chemistry 379 15. Heterocyclic Compounds 414 16. Carbohydrates Oxford 461 17. Amino Acids, Proteins, and Nucleic Acids 495 18. Molecular Rearrangements 520 19. Conversions and Syntheses of Organic Compounds 555 20. Constitutional Problems on Organic Compounds 594 21. Miscellaneous Problems 604

Appendix A Abbreviations of a Few Reagents Used in Chemical Literature 701

Appendix B Reducing and Oxidizing Agents Commonly Used in Organic Chemistry 705

PSOC_FM.indd 5 12/30/2015 5:31:01 PM 200 Problems and Solutions in Organic Chemistry

Ans It is a case of acyloin condensation of diethyl malonate, O O the product is a three-membered cyclic acyloin, α-hydroxyke- − − RCO + R′ OH RCOR′ + OH tone. The mechanism can be shown as follows:

O . 7.14 Prepare trimethylacetic acid from acetic acid. O Ans Trimethylacetic acid can be prepared from acetic acid by C OC2H5 Na C OC2H5 the following sequence of reactions. CH2 . CH2 . C OC2H5 Xylene C OC2H5 Ca(OH)2 O CH3COOH (CH3COO)2Ca CH3COCH3 O Acetic acid Diethyl malonate . + Mg/H − From +2e Na metal H3C CH3 . − CH C C O O O 3 CH3 C OH OH C C OC2H5 CH Pinacol 2 CH2 CH2

C C C OC2H5 H3C O − CH3 O O O + . − H I2/OH − H C C C CH H3C C COO + CHI 3 3 Haloform 3 From reaction CH FEATURES OF − CH3 3 +2e Na metal Pinacolone + H3O

− + O Na OH CH3 C H O C C O 2 CH H3C C COOH CH 2 2 CH2 C C CH OH CH3 − OH Trimethyl acetic acid O Na+ 7.15 Esterification reaction is always catalysed by acids 7.13 Give the B 2 mechanism of ester hydrolysis. AC but de-esterification is catalysed by both acid and alkali Ans BAC2 mechanism of ester hydrolysis can be shown as and the latter is preferred. Explain with suitable examples. follows: Ans Esterification is always acid catalysed because when base is used, it reacts with carboxylic acid (RCOOH) to form an − O O acid anion having poor nucleophilicity and therefore, cannot Over 1500 Problems Slow react with an alcohol (R′OH) in an SN2 type displacement RC OR′ RCOR′ reaction to form ester by the removal of more strong nucle- with Solutions − OH ophilic reagent O–H. De-esterification, however, is possible OH by both acid and alkali according to mechanisms shown here: The book contains more Fast In case of base catalysed esterification: O O than 1500 problems with − − O O RCO + HOR′ RC OH + OR′ solutions to reinforce − − R C OH + OH R C O + H2O Weak nucleophile learning through the BAC2 stands for ‘base catalysed acyl oxygen fission bimo- lecular (2)’. The BAC2 hydrolysis is irreversible because the question-and-answer carboxylate ion R–COO− is resonance stabilized and conse- This part of the reaction cannot occur: quently is a poor nucleophile. It cannot displace OH− from format. R′–OH by S 2 type displacement. O O N S 2 − N − R C O + R′ OH RC OR′ + OH O − O Weak base and Ester Strong − R C O RCO weak nucleophile base Press Alcohols and Ethers 181

configuration at the chiral centre in the product and the abo- 5.21 Account for the following observation.

solute configuration of the product is (S). The course of the − 14 MeO 14 PSOC_Chapter 07.inddreaction 200 is shown here. 12-Aug-14 6:47:11 PM H2C CHCH2Cl MeO H2C CH CH2 Me Me O O Alcohols and Ethers 179 + Et C .. H Et C + not O : OH methyl etherH CH results. ExplainC this result by means 14of the Ans 2 2 H2C CHCH2OMe reaction mechanism. O (a) The structure of 18-crown is given here. Me IllustrationMe of Ans This not a direct Williamson synthesis of an ether. The Ans When twoEt Cdifferent+ MeOH alcoholsEt C OH are used to prepare unsym- ; O O O StructuralOH S 2 Formulaereaction is initiated by a ring opening through a nucleophilic H C N MeO CH − O O O O metrical ether,.. 2then a mixture of2 ethers mayattack be by MeOformed. and this is followed by anotherO intramolec-O + − (R) compound MeO.. TheH book is loaded with manyular nucleophilic substitution resulting into another epoxide. + KF K + F (B) , structural formulae to enableThe sequence of reactions is shown here. O O O O O O H2SO4 UniversityO O O Me .. R OH + R′ OH EtR + OMe R + R′ O R′ + R O R′ Cl + visualizationH OMe.. of the organic Et C + −H O C 14 SN2 1418-crown-6 K coordinated 18-crown-6 OH 2 OH − H C CHCH Cl MeO CH CH CH compounds.MeO 2 2 2 2 H C H2C 2 O O− − CH3(CH2)6CH2Br + F CH3(CH2)6CH2F However, when a mixtureSN1 of t-butyl alcohol and methyl SN2 alcohol is treated in presence of H SO , t-butyl alcohol read- The cavity inside 18-crown-6 is just the right in size Me 2 4 14 MeO H C CH CH + ily forms the corresponding t-butyl cation by dehydration and 2 for coordination2 with the K effectively. The diameter of MeO C Et O that carbocation then reacts with methyl alcohol to give the K+ ion is 2.66 Å. The Na+ is smaller (diameter = 1.96 Å) CH2OH (S)-compound and it is not coordinated so tightly. Therefore, 18-crown-6 corresponding unsymmetrical(C)Oxford ether. The course of the reaction is given here. solubilises potassium salts much more effectively than EXERCISES sodium salt. Thus, reaction between KF and 18-crown-6

Draw the structures and IUPAC names of the isomeric 2CH3 How can you use CH CH OH to get CHproducesCH OD and large concentration of fluoride ions in non polar 5.1 CH3 H SO ° 5.8 3 2 3 2 2 4 + heptanols containing one methyl side chain. CH3CH2D? solvent (substrate itself) which acts as a good nucleop- H C C OH 5.2 What His LucasC reagent?C HowOH is it used to distinguish3 three 5.9 How2 can you convert (CH ) CCH O to neopentyl alco- 3 3 3 = hile to displace bromine from 1-bromooctane. Reaction is classes of alcohols? hol using HCH O as reducing agent? CH = 5.3 Alcohols are neutralCH 3towards alkali but readily forms 5.103 What are the compounds formed when vapourshown of each in the aforementioned diagram. alkoxides witht-Butyl alkali metals alcohol such as Na and K. Offer an expla- of− Hthe followingO compounds is passed through(b) theWhen hot copper 18-crown-6 is dissolvedNumerous in benzene Exercises and then small nation. tube?2 (a) Butan-1-ol, (b) Butan-2-ol (c) 2-Methylbutan-2-ol. amount of KMnO is addedThere then are KMnO more than dissolves 700 in 5.4 Potassium t-butoxideCH is a widely used base in organic reac-CH 5.11 Describe the action of an oxidizing agent on primary, 4 4 tions but the corresponding3 sodium compound is unknown. secondary,3 and.. tertiary alcohols. benzene to give it a purple colour.exercise This questions is called spread ‘purple Give reason. + H OCH H C CO Me H C C 5.12 Write down.. the action3 of the following reagentsbenzene’. on ethyl The structure of theacross coordinated chapters forcompound self- is 5.5 The dehydration3 of n-BuOH with acid gives two isomeric3 and isopropyl alcohol. alkenes. What are they? Which one would be the major com- (a) Na (d) CH COOH givenin presence here. evaluation of concepts. pound? CH3 CH3 3 (b) POCl3 of a few drops of H2SO4 (c) Hot H SO (e) CH COCl 5.6 Whatt-Butyl are three methyl isomeric alcohols ether having the molecular for- 2 4 3 O mula C4H10O? Which of them will react first when a mixture of 5.13 How can you distinguish between (a) methanol and eth- O + O them is treated with one equivalent of acetic acid? anol (b) propan-1-ol and propan-2-ol. − 5.13 Explain why 2-cyclopropylpropan-2-ol reacts with K MnO4 5.7 Identify the compounds A and B in the following reactions. 5.14 Outline the synthesis of each of the following com- HClComment to ongive the stereochemical 2-chloro-2-cyclopropylpropane aspects where necessary. pounds: instead of O O + (a) Methanol from carbon monoxide O 1-chloro-2,2-dimethylcyclobutane.PhCO3H H3O cis-But-2-ene A B (b) Ethanol from ethylene K+ coordinated 18-crown-6 Ans Formation of 2-chloro-2-cyclopropylpropane from (In benzene solution) 2-cyclopropylpropan-2-ol can be shown as follows. © Oxford University Press.5.15 All rightsIdentify reserved. the products in the following sequence of PSOC_Chapter 05.indd 181 .. reactions. 12-Aug-14 6:34:08 PM OH.. OMe + + PSOC_FOTB.indd 6 2-Cyclopropylpropan-2-ol m-CPBA CH OH/H H3O 12/30/2015 5:55:20 PM A 3 BCD H+

+ The course of the reaction and products are shown here. OH .. 2 OMe OMe −H O m-CPBA .. 2 O :

− Cl Methoxycyclohexene A + Cl + CH3OH/H ° 3 cation 2-Chloro-2-cyclopropylpropane + .. OMe + OMe.. OMe .. .. OH The rearrangement leading to the formation of cyclobu- .. .. + OH tane derivative is not observed in this case because that will OH.. .. lead to the formation of a 2° carbocation which is less stable than the 3° cation, although there is a slight decrease in angle CH3OH strain. OMe 5.14 (a) 18-Crown-6 is a useful catalyst for the reaction O OMe + O between KF with 1-bromooctane to give 1-fluorooctane. H3O −H2O .. Explain this fact. Do you expect a similar reaction with OH OH.. NaF? (b) What is purple benzene? B C D

PSOC_Chapter 05.indd 179 12-Aug-14 6:33:57 PM CH3 CHCHCH CHCO2H (D) (CH3)2CH COOH

O3 H2O2 CH3 CH2 CH2 NH CH3 (C) CH3COOH+ HOOC COOH Acetic acid Oxalic acid [HNO2]

20.4 A compound ‘X’ C5H8ON2, when treated with N O nitrousTHE acid yields BOOK an acidic compound ‘Y’, C5H7O2N. Both ‘X’ and ‘Y’ when boiled with aqueous sodium CH3 CH2 CH2 N CH3 hydroxide give ammonia and the same compound ‘Z’,

C5H8O4. ‘Z’ on heating with aqueous acid gives of carbon [HNO2] (CH3)2NCH2CH3 No reaction dioxide and yields the compound ‘A’, C4H8O2. Deduce a possible structure for the compound ‘X’ and elucidate the (D) chemical changes involved. 20.6 The interaction of diphenylketene and styrene results Ans in a compound ‘A’, C22H18O. ‘A’ reacts with methylmag- nesium bromide to give ‘B’, C H O. Dehydration of ‘B’ CN CN 23 22 Exclusive[HNO Chapter] followed by ozonolysis gives a ketoacid ‘D’, which with 2 alkaline hypoiodite forms triphenylsuccinic acid. Identify CH3 CH2 CH CONHon Constitutional2 CH3 CH 2 CH COOH (X) Problems (Y) the compounds ‘A’, ‘B’, and ‘D’ and show the reactions. Ans This chapter trains studentsNaOH –NH3 to analytically think and Ph Ph deduce organic compounds COOH Ph–C C O Ph–C––C=O whichNaOH are represented as += = CH3 CH2 CH COOH Ph CH CH unknown variables in a Ph–CH CH2 – – 2 –NH3 (Z) = given reaction description. (A) Heat –CO2 Press MeMgBr CH3 CH2 CH2 COOH (A) CH Ph CH3 Ph 3

20.5 Four isomeric amines ‘A’, ‘B’, ‘C’, and ‘D’ have the Ph–C––C −H2O Ph–C––C– OH molecular formula C H N. With nitrous acid ‘A’ and ‘B’ 4 11 Ph–CH–CH Ph–CH–CH2 give isomeric products C4H10O. ‘A’ gives C2H4O2 when (B) oxidized vigorously, whereas ‘B’ gives C H O . With 4 8 2 O3 nitrous acid, ‘C’ gives an organic product containing nitrogen, whereas ‘D’ does not react. Identify the four iso- Ph Ph CH3 meric amines and elucidate the reactions involved. I /NaOH 2 Ph C COOH Ans Presentation Based on Various UniversityPh–C––C=O – –– Classes of Compounds Ph–CH–COOH Ph–CH–COOH CH CH CH NH (CH ) CH CH NH 3 The2 textCH exemplifies2 2 the2 subject matter3 2 2 2 (C) Triphenylsuccinic acid according(A) to the various classes of organic(B) compounds and their associated reactions. 20.7 A carboxylic acid ‘A’, C H O , on careful oxida- CH CH CH NH CH (CH ) NCH CH 9 16 2 3 2 2 3 3 2 2 3 tion gives propionic acid and a dibasic acid ‘B’, C H O . (C) (D) 6 10 4 When ‘A’ is completely oxidized with chromic acid, it Oxford yields two moles of acetic acid per mole of ‘A’. Catalytic CH3 CH2 CH2 CH2NH2 (A) reduction of ‘A’ gives an acid ‘C’, C9H18O2, which, after being subjected to two successive Barbier–Wieland degra-

[HNO2] dations, yield a ketone ‘D’, C7H14O. Oxidation of ‘D’ with sodium hypobromite gives bromoform and hexanoic acid. Vigorous [O] CH CH CH CH OH CH COOH Deduce the structure of ‘A’. 3 2 2 5 2 Alcohols and Ethers3

6 Aliphatic Carbonyl Compounds PSOC_Chapter 20.indd 595 8/12/2014 6:20:46 PM Alcohols OH Hg(OAc)2 5.1 Convert CH CH(OH) CH Cl to CH CH(Cl)CH OH. CH3 CH CH2 CH3 CH CH2 7 3 2 3 2 THF, H O Propylene 2 Aliphatic Acids and their Ans The conversion can be done as follows. First step is the HgOAc conversion the chlorohydrin to an epoxide by base and then ring opening by acid (HCl). Ring opening takes place through NaBH4, OH Derivatives the incipient formation of more stable carbocation. 6.1 Justify the following statements regarding a carbonyl + − .. + − δδ group with suitable examples. or Cl OH C=O.. C–O..: C–O NaOH (a) The group has planar geometry. CH3 CH CH2 CH CH CH CH3 CH CH3 Resonating structures of > C O group 3 .. 2 (b) It is a polar group and can function as an acid as well = : Isopropyl alcohol OH OH .. O .. as a base. It is to be noted that in >C O group, the carbon atom is 5.3 = HCl

Ans face. + ion, the Cl Cl increased due to −I effect. Inductive effect rapidly decreases CH3 CH CH2OH CH3 CH CH2 the >C as the distance between the electron-withdrawing group .. - Ans + and COOH decreases. In case of Cl CH COOH, the O © Oxford University Press. All rights reserved. – – 2– H of >C + from acidic Ans = Cl-atom is nearer to the –COOH group, but in Cl–CH2–CH2 –COOH, it is away from the –COOH group. Therefore, in − + O + H 5.2 Starting from an appropriate alkene, show all the Cl–CH2–CH2–COOH, −I effect on –COOH is much less steps in the synthesis of t-Butyl alcohol and isopropyl alco- and n and consequently it is much weaker than Cl–CH2–CH2 COOH. hol by oxymercuration–demercuration. (σ sp2 – Ans Oxymercuration and demercuration reaction leads to PSOC_FOTB.indd 7 sp e 7.4 Between acrylic acid and propionic acid, which one is 12/30/2015 5:55:24 PM Markowanikov way of hydration of alkenes. Therefore, isobu- of oxygen. The other bond is a weak+ Hpi-bond+ (π-bond), 1 Nomenclature of Organic Compounds

1.1 Give the structures of the following IUPAC names: (i) (j) CH=O O (a) 1-Allyl-2-ethyl-4-(prop-1-en-2-yl)-3-vinylcyclobuta- 1,3-diene CH=O (b) 3-(5-Amino-2-nitrophenyl)-2-methylpropanal O (c) 3-(Prop-1-enyl)hex-3-en-2-one Press (d) 4,4-Dipropylcyclohexa-2,5-dienone 1.2 Give IUPAC names of the following compounds along (e) 8-Methyl-6,7-dimethylene-4-oxononanoic acid with the stereochemical descriptors. (f) 2-(Prop-1-en-2-yl)-7-vinyl-1,2,3,4,5,6,6,8-octahydrona- O O phthalene (a) (b) (g) 2-(1-Methyl-7-vinyl-1,2,3,4-tetrahydronaphthalene-2- COOH yl) acrylic acid (h) 5-Ethyl-2,9,12-trimethyl-10-methylenetridec- 1-en-6- one (i) Octa-2,4-dienedial (c) (d) COOH (j) 4,8,9,11-Tetramethyl-5-oxododecanal University Ans COOH (a) (b) NH2 COOCH3 CH3 O (e) (f) H Cl COOH Br NO2 (g) Br (h) Cl Oxford CH 3 (c) O (d) O Cl

(i) CH3 (j) Br

(k) (l)

(e) O (f) Br COOH Ans (a) 4,4-Di((E)-prop-1-enyl)cyclohexa-2,5-dienone (b) (E)-8-Methyl-6,7-dimethylene-4-oxonon-2-enoic acid (g) COOH (h) O (c) (2R,7R)-2-(s-cis(But-1,3-dien-2-yl)-7-vinyl-1,2,3,4,5,6, 6 2 7,8-octahydronapthalene 1 (d) (E)-2-(But-2-enyl)benzene-1,3-dicarboxylic acid 13 (e) (E)-2-(But-2-enyl)-3-(methoxycarbonyl)benzoic acid

PSOC_Chapter 01.indd 1 12/30/2015 12:02:59 PM 2 Problems and Solutions in Organic Chemistry

(f) (1S,2S,4R)-2-Bromo-1-chloro-4-methylcyclohexane (o) (g) (1R,2R,4S)-2-Bromo-1-chloro-4-methylcyclohexane (h) 7-Chloronon-1-en-8-yne (i) (S,E)-7-Methylnona-1,4-dien-8-yne (j) (R,5E,8Z)-3-Bromodeca-5,8-dien-1-yne (p) COOH (k) (R,Z)-4/-(1-Bromopent-2-en-4-ynyl)-3,4-dimethylbi- phenyl (l) (2R,4aS,8aS)-2,4a,8a-Trimethyldehydronaphthalene 1.3 Give IUPAC names of the following compounds along (q) (r) with the stereochemical descriptors wherever applicable.

(a) Ans (a) 2,5,6,7-Tetramethyldecane (b) (E)-8-Methyltetradec-3-en-13-ynoic acid (b) COOH (c) (E)-Hepta-1,3-dien-6-yne (d) (4E)-4-Methylnona-2,4-dien-7-yne (e) (2Z)-7-Oxo-2-(prop-1-enyl)hept-2-en-5-ynoic acid (f) (S,2Z,5E)-4-Bromo-4-methylhepta-2,5-diene (g) (R,Z)-2-Bromo-2-mercaptooct-5-enoic acid (c) (h) (2R,3r,4S)-2,3,4-Trihydroxypentanedial (i) (2R,8S,Z)-2-Bromo-8-chloro-8-hydroxy-2-mercaptonon- (d) 5-enoic acid Press (j) (2R,4R)-2,3,4-Trihydroxypentanedial (k) (2Z,5Z)-4-Bromo-4-methylhepta-2,5-diene (l) (2R,3R,4S)-2,3,4-Trihydroxy-4-formylpentanoic acid (e) HOOC CH O (m) (2S,3S,4R)-2,3,4-Trihydroxy-5-oxohexanal (n) (2R,3s,4S)-2,3,4-Trihydroxypentanedial (f) Br (o) 2,5,6,7-Tetramethyldecane H CH3 (p) (E)-8-Methyltetradec-3-en-13-ynoic acid (q) (E)-Hexa-1,3-dien-6-yne H C H H H 3 (r) (2E,4E)-4-Methylocta-2,4-dien-6-yne (g) Br (h) CHUniversity=O 1.4 Write the IUPAC names of the following compounds. COOH H– C–H (a) (b) (c) SH COOH O O H– C–OH HOOC– C–H H– C–OH COOH CH O Ph Et Me Et

(d) (e) OOO (i) Br Oxford (j) CH O Cl COOH H– C–OH CH3–C–C–C–CH3 SH OH H– C–OH (f) O (g) O (h) HO– C–OH COOH CH O (k) Br H3C CH3 Ph CH O

H H H H (i) (j) (k) O

(l) COOH (m) COCH3 (n) CH O H– C–OH H–C–OH H– C–OH H– C–OH HO–C–H HO– C–H (l) O (m) CH O (n) O O OH H– C–OH H–C–OH H– C–OH OH OMe CH O CH O CH O

PSOC_Chapter 01.indd 2 12/30/2015 12:03:09 PM Nomenclature of Organic Compounds 3

(o) O (c) Br COOH CH2OH HOOC Cl (d) COOH (e) Ans (a) Methanetricarboxylic acid NC CN (b) 4-Ethyl-4-phenylcyclohexanone (c) 4-Ethyl-4-methylcyclohexa-2,5-dienone (f) (g) (d) 3-(Prop-1-en-2-yl)cyclopent-1-ene (e) Pentane-2,3,4-trione (h) (i) (f) 4-Oxo-1-phenylcyclohexanecarbaldehyde Br HOOC Br (g) Bicyclo[2.2.2]octan-2-one (h) Spiro[3.4]octane-2-carboxylic acid (i) 4-Vinyloct-1-en-7-yne Ans (j) 1-Ethynyl-2-vinylcyclohexane (a) (3E,5E)-Octa-1,3,5-trien-7-yne (k) 1-(3,6-Dimethylenecyclohex-1-enyl)ethanone (b) (E)-But-2-ene-1,2,4-tricarboxylic acid (l) 2-Hydroxycyclohepta-2,4,6-trienone (c) (Z)-4-Bromohex-2-enedioic acid (m) 3-Hydroxy-4-methylpent-4-enal (d) (Z)-4-Cyano-2-[(E)-2-cyanovinyl]but-2-enoic acid (n) Methyl 2-methyl-3-oxobutanoate (e) (2Z,4Z)-3-Methylocta-2,6-diene (o) 4-Chloro-6-hydroxyhexan-3-one (f) (2Z,6E)-Octa-2,6-diene (g) (Z)-3-Ethynylhexa-1,3-diene 1.5 Are the following IUPAC names correct? If not, give (h) (2E,6Z)-4-Bromoocta-2,6-dienePress their correct IUPAC names. (i) (E)-3-Bromo-2-[(Z)-prop-1-enyl]hex-4-enoic acid (a) 1,3,4,5,6-Pentabromo-1,2,6-trichlorohexane 1.7 Give the IUPAC names of the following monovalent (b) 5-Ethoxy-2-methyl-5-oxopentanoic acid radicals. (c) 2-Methyl-4,6-dioxoheptanal (a) CH C (b) CH CCH (c) (d) Biacetyl 2 CH3CH=CH– (e) Butane-1,3-dione (d) CH CH CHCH − (e) CH CH CH CHCH − (f) Diethyl oxalate 3 = 2 3 2 = 2 (f) (g) (g) 4-Nitropentanenitrile CH2=CHCH=CH– HC CCH=CHCH2− (h) Octa-5,7-dien-1,3-diyne Ans (i) Butane-1,2,4-tricaboxylic acid (a) Ethylnyl (e) Pent-2-enyl (j) 4-Cyano-2-(2-cyanoethyl)butanoic acid University (b) Prop-2-ynyl (f) Buta-1,3-dienyl (k) 3-Propylidenepent-1-en-5-yne (c) Prop-1-enyl (g) Pent-2-en-4-ynyl Ans (d) But-2-enyl (a) Incorrect (Correct name: 1,2,3,4,6-Pentabromo-1,5,6- 1.8 Give the IUPAC names of the following structures. trichlorohexane) (a) (b) CH (c) CH CH (b) Incorrect (Correct name: 4-Carbethoxy-2-methylbutanoic 2 2 3

acid) CH3 (c) Correct Oxford (d) Incorrect (Correct: Butane-2,3-dione) CH3 (e) Incorrect (Correct: 3-Oxobutanal) (f) Incorrect (Correct: Diethyl ethanedioate) (d) CH3 (e) (g) Correct C=CH2 CH3 (h) Incorrect (Correct: Octa-1,3-diene-5,7-diyne) (i) Correct CH3 CHCH2 CH2 CHCH2 CHCH3 (j) Correct (f) (k) Incorrect (3-Ethynylhexa-1,3-diene) CH2 1.6 Give the E,Z nomenclature of the following compounds. Ans (a) (a) 6-Methylcyclohepta-1-en-4-yne (b) 5-Methylidenecyclopenta-1,3-diene (c) 1-Ethyl-4-methylcycloocta-1,3,5,7-tetraene (b) COOH (d) Prop-1-en-2-ylbenzene COOH (e) 4-Methyl-2,7-diphenyloctane HOOC (f) Diphenylmethane

PSOC_Chapter 01.indd 3 12/30/2015 12:03:20 PM 4 Problems and Solutions in Organic Chemistry

1.9 Give the structures of the following names. Ans (a) 12354 876 (a) Perfluorohexane CH3–CH2–O–CH2–CH2–O–CH2–CH3 (b) Perchloro(2-methylpentane) 3,6-Dioxaoctane (c) Perbromocyclohexane (d) 4′-Chloro-m-terphenyl 1234 5678 (b) HOCH CH O CH CH O CH CH OH (e) 4-(1-Propyl)octan-2-ol 2 2 2 2 2 2 (f) 4-(2-Butyl)heptane-2,6-diol 3,6-Dioxaoctane-1,8-diol (g) 2-(Hydroxymethyl)heptane-1,6-diol 1 O (c) O (d) Ans 4123 CH 3 CH 2 C CH2 2 (a) CH3 3 CF3–CF2–CF2–CF2–CF2–CF3 CH3 CH Perfluorohexane 3 1,2-Epoxy-2-methylbutane 1,3-Epoxy-2,2-dimethylpropane (b) (c) Br CCl3 CCl CCl2 CCl2 CCl3 Br (2-Ethyl-2-methyloxirane) (3,3-Dimethyloxetane) Br Br 1 CCl3 Br (e) 910 Br O 2 Perchloro(2-methylpentane) Br Br 8 5 Br Br Br Br 3 Perbromocylohexane 67 4 1-Oxaspiro[4.5]decane (d) 2′ (Not 4-Oxaspiro[4.5]decane) 1′ 3′ 1 1″ 9 10 1 (f) PressO 2 6′ 4′ Cl 5′ 8 5 6 4′-Chloro-m-terphenyl 3 7 N H 4 (e) OH 123 9-Oxa-6-azaspiro[4.5]decane CH CH CH not 7-Oxa-10-azaspiro[4.5] (6,9 is lower than 7,10) 4123 2 3 CH3 CH2 CH2 CH 8765 (g) CH CH CH CH CH CH = 2 2 2 2 3 765432 1 4-(1-Propyl)-octan-2-ol HC C CH2 CH2 C=CH CHO 3-Vinylhept-2-en-6-ynal (f) OH OH University 67 45 3 12 (h) OHC CH2 CH2 CH2 CH2 CH2 CHO CH3 CH CH2 CH CH2 CH CH3 21 43 Heptanedial CH3 CH CH2 CH3 4-(2-Butyl)heptane-2, 6-diol (i) CH3 1 2 3 OHC CH CH CH CH (g) 7 6 45 23 1 2 3 4 CH3 CH CH2 CH2 CHOxford2 CH CH2 OH CHO 3-Ethyl-2-methylbutanedial OH CH2 OH 2-(Hydroxymethyl)heptane-1,6-diol (j) CHO 1 1.10 Give the structure of the following IUPAC names. 2 CHO (a) 3,6-Dioxaoctane (b) 3,6-Dioxaoctane-1,8-diol (c) 1,2-Epoxy-2-methylbutane Naphthalene-1,2-dicarbaldehyde (d) 1,3-Epoxy-2,2-dimethylpropane (e) 1-Oxaspiro[4.5]decane (k) 1 (l) 4 S 2 CHO 5 3 (f) 9-Oxa-6-azaspiro[4.5]decane 5 (g) 3-Vinylhept-2-en-6-ynal 6 4 NH 2 CHO 3 N (h) Heptanedial 1 (i) 3-Ethyl-2-methylbutanedial Thiazolidine-2-carbaldehyde Pyridine-2-carbaldehyde (j) Naphthalene-1,2-dicarbaldehyde (m) O (k) Thiazolidine-2-carbaldehyde 12345 (l) Pyridine-2-carbaldehyde CH2=CH–C–C CH (m) Pent-1-en-4-yn-3-one Pent-1-en-4-yn-3-one

PSOC_Chapter 01.indd 4 12/30/2015 12:03:30 PM Nomenclature of Organic Compounds 5

1.11 Give the structures of the following names. (h) CH3 (a) 2,3,5-Trimethylhexane 43 12 CH3CH2CHCH2 (b) 2,7,8-Trimethyldecane 13 12 711–8 456 123 (c) 4-Ethyl-5-methylnonane CH3CH2(CH2)4CHCH2CHCH2CH2CH2CH3 1234 (d) 5-Ethyl-2,2-dimethylheptane CH3CHCH2CH2CH3 (e) 7-(1,2-dimethylpentyl)-5-ethyltetradecane 5-(1-Methylbutyl)-7-(2-methylbutyl)tridecane (f) 4-Ethyl-5-methyloctane (g) 4-Isopropyl-5-propyloctane (i) CH3 (h) 5-(1-Methylbutyl)-7-(2-methylbutyl)tridecane 12 3 (i) 5,5-Bis-(1,1-dimethylpropyl)-2-methyldecane CH3CCH2CH3 (j) 2,3,5-Trimethyl-4-propylheptane 123 45 678910 CH3CHCH2CH2CHCH2CH2CH2CH2CH3 (k) 7,7-Bis-(2,4-dimethylhexyl)-3-ethyl-5,9,11-trimethyl- 12 3 tridecane CH3 CH3CCH2CH3 (l) 4-(1-Isopropylbutyl)-3-propylundecane CH3 (m) 3,4-Diethylhexa-1,3-dien-5-yne 5,5-Bis(1,1-dimethylpropyl)-2-methyldecane (n) 3-Propylhex-1-en-4-yne

Ans (j) CH3CH2CH2 CH3 123 4567 123 CH3 (a) CH3CH2CHCHCHCHCH3 654321 CH CHCH CH CHCH 3 2 3 CH3 CH3

CH3 CH3 2,3,5,-Trimethyl-4-propylheptane 2,3,5-Trimethylhexane Press CH CH (k) 3 3 CH3 CH2CH3 (b) CH3 1213 11 8910 456 123 10 89 1234567 CH CH CHCH CHCH CH CHCH CHCH CH CH CH CHCHCH CH CH CH CHCH 3 2 2 2 7 2 2 2 3 3 2 2 2 2 2 3 C 1213 11 8910 123456 CH3 CH3 CH3CH2CHCH2CHCH2 CH2CHCH2CHCH2CH3 2,7,8-Trimethyldecane CH3 CH3 CH3 CH3

(c) CH2CH3 7,7-Bis-(2,4-dimethylhexyl)-3-ethyl-5,9,11-trimethyltridecane 67 89 67 54 123 CH3CHCHCH2CHCHCH2CH2CH3 (l) CH2CH2CH3 CH3 University123 45–9 10 11 CH3CH2CHCH(CH2)5CH2CH3 4-Ethyl-5-methylnonane CH3CH2CH2CHCHCH3 (d) CH3 13 4567 2 13 CH CH CH CHCH CH CCH 3 3 2 2 2 3 4-(1-Isopropylbutyl)-3-propylundecane CH2CH3 CH3 (m) CH2CH3 5-Ethyl-2,2-dimethylheptane 614 235 Oxford HC CC CCH CH 2 (e) CH3 = = 12 345 CH2CH3 CH3CHCHCH2CH2CH3 14 456713–8 123 3,4-Diethylhexa-1,3-dien-5-yne CH3(CH2)6CHCH2CHCH2CH2CH2CH3 465 CH2CH3 (n) C CHCH3 7-(1,2-Dimethylpentyl)-5-ethyltetradecane 123 CH2=CHCHCH2CH2CH3 (f) CH2CH3 123 45678 123 3-Propylhex-1-en-4-yne CH CH CH CHCHCH CH CH 3 2 2 2 2 3 1.12 Give the structures of the following names. CH3 (a) 5-Ethylhepta-1,3,6-triene 4-Ethyl-5-methyloctane (b) 2-Butyl-5-ethynylhepta-1,8-diene

(g) CH3CHCH3 (c) 7-Methyltrideca-1,10-diene-4,8-diyne 12345678 (d) 4-Vinylhept-2-en-5-yne CH CH CH CHCHCH CH CH 3 2 2 2 2 3 (e) 6-Methylcyclohept-1-en-4-yne CH3CH2CH2 (f) 5-Methylidenecyclopenta-1,3-diene 4-Isopropyl-5-propyloctane (g) 1-Ethyl-4-methylcycloocta-1,3,5,7-tetraene

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Ans (g) (a) 7 615 4 23 CH2 CHCHCH CHCH CH2 C CH 5-Ethynylhepta-1,3,6-triene

(b) 1 CH2 C CH 2 3456 7 CH [CH ] CCH CH CHCH CH 3 2 3 2 2 2 (h) j k l m n a 2-Butyl-5-ethynylhepta-1,6-diene Benzene i b + 2 (Attached ring) h g f e d c (c) CH3 13 12 11 78910 6154 23 Anthracene CH CH CH CHC CCHCH C CCH CH CH 3 2 2 2 2 (Base component) 7-Methyltrideca-1,10-diene-4,8-diyne

a 1 j (d) CH CH2 (e) 2 7 612354 7 3 CH3C CCHCH CHCH3 CH 6 4-Vinylhept-2-en-5-yne 3 4 5 (i) j kl m n a 6-Methylcyclohept-1 Benzene b 2 -en-4-yne i Press+ (Attached ring) h g f e d c (f) CH2 5 Anthracene 1 4 (Base component) 23 a 5-Methylidenecyclopenta h -1,3-diene (Trivial name: Fulvene)

CH CH (g) 8 1 2 3 7 2 University (j) 1 (k) 1 6 3 6 2 6 2 5 4 7 Bridgehead carbons CH3 5 3 5 3 1-Ethyl-4-methylcycloocta 4 4 -1,3,5,7-tetraene

1 1.13 Give the names of the following fused ring hydro- (l) 2 (m) Spiro atom 8 3 carbons. Oxford 9 10 7 4 6 5 (a) (b)

(n) (o)

6 5 1 9 10 12 6 1 10 1 2 (p) (q) (c) (d) 9 2 8 5 2 3 7 4 5 8

4 3 4 3 7 6 4 3 7 6 5 8 9

1 23 11 12 12 (r) 9 10 (s) 2′3′ (e) (f) 2 10 3 4 8 5 4′ 1′ 1 9 4 3 5′ 6′ 6 5 87 56 7 6 4

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Ans (b) HOOC CH2 CH2 CH2 CH2 COOH (a) Dibenzophenanthrene Hexanedioic acid (b) Benzanthracene (In the case of saturated dicarboxylic acid (Not Benzoanthracene) with no branching, one need not (c) Pentalene give any number to indicate the positions (d) Heptalene of COOH groups) (e) Octalene (c) (f) Biphenylene CH=CH2 (Not Diphenylene; two benzene ringsare ortho-fused to CH3–CH=CH–CH–C CH the central ring of four carbon atoms) 3-Ethynylhexa-1,4-diene (g) Triphenylene (In the case of compounds having double bonds (Three benzene rings are ortho-fused to the central ring of and triple bonds, the base name should include six carbon atoms) the maximum number of double bonds) (h) Dibenzo[a,j]anthracene (i) Dibenzo[a,h]anthracene (d) O (j) Bicyclo[2.2.1]heptane CH3 C CH2 CH2 CH=O (k) Bicyclo[2.2.0]hexane 4-Oxopentanal (l) Bicyclo[4.2.2]decane (–CH=O group gets preference over C=O group (m) Spiro[3.4]octane in numbering the chain. The position of the (Total number of carbons is eight) terminal –CH=O group need not be given (n) Spiro[4.5]decane any number) (Not Spiro[5.4]decane; total number of carbons is ten) Press (e) HOOC CH CH CH C C COOH (o) Spiro[3.3]heptane 2 (Total number of carbons is seven) Hept-2-en-5-ynedioic acid (p) Spiro[3.5]non-5-ene (Since we have the option of numbering the (q) Spiro[4.6]dec-1-en-6-yne carbon chain, the double bond gets a lower number) (r) Spiro[4.5]deca-1,6-diene (f) (Not Spiro[4.5]deca-1,9-diene; 1,6 is lower than 1,9) CH=O O

(s) Cyclohexylbenzene HOOC–CH–CH2–CH2–C–COOH 1.14 Are the following IUPAC names correct? If not, give 2-Formyl-5-oxohexanedioic acid the correct name along with the structures. Give your rea- (–CH=O group gets preference in citation sons in brief. Universityover C=O group, when there is an option) (a) 1,5-Dibromohexa-3,5-dien-1-yne (g) CN (b) Hexane-1,6-dicarboxylic acid NC CH CH CH CN (c) 3-Ethynylhexa-1,4-diene – 2– – 2– (d) 4- Formylbutan-2-one Propane-1,2,3-tricarbonitrile (e) Hepta-2-en-5-ynedioic acid (–CN group is named as carbonitrile when they are supposed to yield carboxylic acid (f) 5-Formyl-2-oxohexanedioic acid on hydrolysis in an aliphatic chain) (g) Propane-1,2,3-tricarboxylicOxford acid (h) 3-Isocyanatopropylcyanate NCO–CH2–CH2–CH2–NCO (i) Isopropanol (h) (j) Diaziridine-1-carboxylic acid 3-Isocyanatopropylcyanate [ NCO group (cyanate) gets preference over (k) 7-Bromo-hept-4,6-dien-2-ynoic acid – –OCN (isocyanate group)] (l) Octa-4,6-dien-2-yndioic acid (i) Ans OH

(a) Incorrect (e) Correct (i) Incorrect CH3 CH CH3 (b) Correct (f) Incorrect (j) Incorrect Propan-1-ol (c) Correct (g) Correct (k) Correct (Isopropanol is a wrong name (d) Incorrect (h) Correct (l) Incorrect because there is no hydrocarbon like The correct names and the corresponding structures are given isopropane) here, with explanations as necessary. (j) HN NH

(a) Br–CH=CH–CH=CH–C C–Br H COOH 1,6-Dibromo-2,3-dien-5-yne Diaziridine-3-carboxylic acid (Numbering should start from the left-hand side (Numbering should start from the nitrogen according to IUPAC rule) atoms of the ring)

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(h) 1 2 (i) 1 (k) Br – – – – COOH O O = = 3 2 7-Bromohepta-4,6-dien-2-ynoic acid 8 O 6 3 (Numbering should start from the side of 7O 4 5 O 5 the –COOH group which is the principle 6 O 4 functional group) 1,3,5,7-Tetroxocane 2H,4H-1,3-Dioxine (l) (Or simply 4H-1,3-Dioxine) HOOC–=–=– – COOH Octa-2,4-dien-6-ynedioic acid (j) 1 N 2 (Since there is a choice, numbering should start 6 N

from the double bond end) 5 3 N 1.15 Give the names of the following heterocyclic com- 4 pounds based on the Hantzsch–Widmann system. 1,2,4-Triazine (The locant set ‘1,2,4’ is lower than (a) 1H-Azirene other possible sets ‘1,2,5’; ‘1,3,5’; or ‘1,4,5’) (b) Azete (c) Oxirane (k) 1 (d) Oxetene 7 P 2 (e) 2-Ethyl-3-methylaziridine 3 6 P (f) 1,4-Diphenylazetidine 5 4 (g) 1,3-Dithiolane (h) 1,3,5,7-Tetroxocane 4H-1,3-Diphosphepine (i) 2H,4H-1,3-Dioxine (Hetero atoms get preference to indicate hydrogenPress for the lowest locants) (j) 1,2,4-Trazine (k) 4H-1,3-Diphosphepine 1 1 (l) 1,3-Oxathiolane (l) O (m) S 5 2 (m) 1,3-Thiazole 5 2 (n) 6H-1,2,5-Thiadiazine 4 N S (o) 2H,6H-1,5-2-Dithiazine 4 3 3 1,3-Thiazole (p) 1,3,2-Diazarsetidine 1,3-Oxathiolane (q) 1,4,2-Oxazaphospholidine (1-Oxa-3-thiolane (r) 1,2,4,3-Triazasilolidine is incorrect) Ans The structures of the aforementioned compounds are 1 1 University (n) S (o) S 2 2 given here. 6 N 6 NH 5 3 5 H 4 N 3 S 3 (a) 1 (b) HC CH N 4 4 3 2 2 HC CH HC N1 6H-1,2,5-Thiadiazine 2H,6H-1,5,2-Dithiazine 1H-Azirene Azete (Numbering begins (Numbering begins 1H-Azirine (Traditional) with the sulfur atom with the sulfur atom. and the set ‘1,2,5’ is ‘Thia’ prefix gets preference 1 OxfordHC CH (c) (d) 3 4 2 lower than the set over ‘aza’ and that O ‘1,3,6’) is why the order of locants is 3 2 HC O ‘1,5,2’ and not ‘1,2,5’.) HC CH 2 1 Oxirane Oxetene (p) 12 (q) 1 HN AsH O H 2 (e) 1 5 N 3 PH 4 32 NH HN 3 CH3 HC CH CH2 CH3 1,3,2-Diazarsetidine 4 2-Ethyl-3-methylaziridine 1,4,2-Oxazaphospholidine (Substituents are cited in alphabetical order) (Not 1,4,2-Oxaazapholidine) (r) H 1 N (f) 23 (g) S Ph HC CH2 5 2 NH 4 1 HN SiH2 H2C N Ph 4 S 3 1,2,4,3-Triazasilolidine 1,4-Diphenylazetidine 1,3-Dithiolane (The locant set ‘1,3’ is lower 1.16 Give the names of the following isotope labelled com- than ‘1,4’) pounds.

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14 1 1 910 1 (a) CH4 (b) CH3D (c) CD2Cl2 (d) (e) (f) 2 O 2 2 . 6 6 . . 8 5 14 18 CH NH ND (d) CH2NH2 (e) H O 2 2 (f) 2 3 5 HO 1 5 3 3 4 7 6 4 6 2 4

5 3 2 3′ 2′ 2 3 4 (g) (h) . 1 3 4′ 1′ 1 4 (g) 14 (h) CH3 CH2COOC2H5 4 9 . 2 5′ 6′ 56 14 CH3–CH2–CH–CH=C[ H2] CH2COONa 8 5 7 6 D (i) 2 (j) CH3–CH2–O[ H] D D + + + (i) CH3 (j) CH3CH2CH2 (k) CH3CHCH3 D D (l) + (m) O (n) + + + CH2 CH2 D 2 1

1 +++ (k) O (l) (o) 4 + (p) 2+ (q) 14 C CH2–CH–CH2 HO [ C]H2–NH2 1 2 CD2 + 2 3 4 Press + + 3 − 1 – (r) CH2–CH2–CH2–CH2 (s) CH (t) CH3 CH CH3 3 2 (m) CH2DCOOH (n) CH3–COOD 1234 14 1234 − − (o) CH3–CH2–CH2–CH2[ C]OOD (p) CHCOOD (u) (v) CH CH C C CH3 CH2 CH2 CH2 3– 2– – Ans 14 (a) Propyl (q) [14C]H CH COOH (r) H[ C]OONa 3– 2 (b) Propan-2-yl or 1-Methylethyl or Isopropyl (Traditional) Ans (c) Cyclopenta-2,4-diene-1-yl (a) (14C)Methane University (d) 2H-Pyran-6-yl 2 (e) Bicyclo[2.2.1]heptan-2-yl (b) ( H1)Methane 2 (f) Spiro[4.5]decan-8-yl (c) Dichloro( H2)methane (d) 1-[Amino(14C)methyl]cyclopentanol (g) 1H-Phenalen-4-yl (e) 1-(Aminomethyl)cyclopentan(18O)ol or 1-(Aminome- (h) 1,1′-Biphenyl-3-yl thyl)(18O)cyclopentanol (i) Methylium *Methyl cation 2 (f) (N,N- H2)Cyclohex-2-en-1-amine (j) Propylium *Propyl cation (g) Sodium ethyl(2,3-14C )succinate 2 Oxford (k) Propyl-2-ylium *Propan-2-yl cation 2 (h) 3-Methyl[1,1- H2]pent-1-ene (Here the locant is part of (l) Cyclobutylium *Cyclobutyl cation the parent hydrocarbon name) (m) Furan-2-ylium *Furan-2-yl cation (i) Ethan[2H]ol or [O-2H]Ethanol 2 (n) Ethane-1,2-bis(ylium) (j) [ H6]Benzene 2 (o) Cyclobut-3-ene-1,2-bis(ylium) (k) [2,2- H2]-1-(2H)-Naphthalenone (l) 1-(Amino[14C]methyl)cyclopentanol (Note that the charged carbon gets priority in numbering) 2 (p) Cyclohexane-1,1-bis(ylium) *Cyclohexylidene dication (m) [2- H1]Acetic acid (n) [O-2H]Acetic acid or Acetic[2H]acid (q) Propane-1,2,3-tris(ylium) (o) [1-14C]Pentan[2H]oic acid or [1-14C, O-2H]pentanoic acid (r) Butane-1,4-bis(ylium) (p) Cyclohexane[2H]carboxylic acid (s) Methanide *Methyl anion (q) 4-([2-14C]Ethyl)benzoic acid (t) Propan-2-ide 1-Methylethanide (r) Sodium [14C]formate *Propan-2-yl anion 1.17 Give the names of the following radicals and ions. *1-Methylethyl anion (u) Butan-1-ide *Butan-1-yl anion (a) . (b) . (c) . (v) But-1-yn-1-ide *But-1-yn-1-yl anion CH3CH2CH2 CH3CHCH2 1 5 2 1.18 What is meant by λ, δ, and ∆ conventions in naming 4 3 organic compounds? Give examples.

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11 1 Ans l-convention: It is a method of describing non-standard 9 1 6 10 2 5 2 bonding numbers of skeletal atoms in parent hydrides. S S A non-standard bonding number of a neutral hetero atom in a 8 3 n 6 4 3 structure is denoted by the symbol l , where n is the number 7 5 4 4 2 4 2 of non-standard bonds. A few examples are given here. 2 2λ δ ,5λ δ -Thieno[3,4-c]thiophene 10δ -Benzo[9]annulene 123 CH SH (C6H5)3PH2 3– 5 H2PPH3PH2 11 Triphenyl-λ5-phosphane 9 1 Methyl-λ6-sulphane 2λ5-Triphosphane 10 (Phosphorus atom has 2 (Sulphur atom has 8 non-standard bonding non-standard bonding 3 number 5) 6 number 6) 7 5 4 8δ2-Benzo[9]annulene H H 1 1 2 6 S 2 S 1 7 3 N 2 Cl 3 S 5 N S 6 3 Cl 4 4 5 N 4 4 1λ -Thiazine 1λ4,3-Dithiepin (IUPAC) (Sulphur atom has 1λ4-,1,3-Dithiepin (CAS) 2,2-Dichloro-4H-2λ6δ2-1,3-benzothiadiazine non-standard bonding number 4) (CAS stands for chemical abstract service) ∆-convention: If the cyclic component and the side chain are linked together through a double bond, the locants of δ-convention: The presence of contiguous formal double Press this bond are placed as superscripts to a Greek capital delta bonds at a skeletal atom in a cyclic parent compound whose ( ). The symbol is inserted between the cyclic and the acy- name normally represents the structural unit having maxi- ∆ clic component. The locant for the cyclic part is placed mum number of non-cumulative double bonds is described earlier. by the symbol ‘δc’, where ‘c’ is an Arabic numeral denoting

the number of contiguous double bonds attached to that par- αβ c ticular skeletal atom. The symbol ‘δ ’ is always preceded by CH CH2 COOH the concerned locant. The hetero atom exhibiting a non-stand- 1 2 ard bonding number can be associated with contiguous formal double bonds in a cyclic parent hydride. In such cases the symbol for the non-standard bonding number is alsoUniversity to be 1,β incorporated in the name. Illustrative examples are given here. Indene-∆-propionic acid

EXERCISES

1.1 In the following pairs, state which name is correct and (i) (2,3,6,8)-, (2,4,5,7)-, (3,4,5,6) which isn’t. Oxford (ii) 2, 2′ and 1′, 2 (a) Pentan-2-ol and Pentane-2-ol (iii) (N, a, 1,2) and (1,2,4,6) (b) Pentane-2,4-dione and Penta-2,4-dione (b) What does the following letter/letters or combination of (c) 1,2,N,N-Tetraaminobenzene and N,N,1,2-Tetraminoben- letters indicate in a structure of an organic compound? zene peri, s, rac, m, abeo, seco, nor neo, friedo, vic, as. (d) 1,3,5,7-Tetroxocane and 1,3,5,7-Tetraoxacane (c) Decide which on of the following names are correct or (e) Thialdehyde and Thioaldehyde incorrect in each pair according to IUPAC rules of nam- (f) Imidoamidic acid and Imidamidic acid ing organic compounds. Give reasons wherever neces- (g) Carboximidic acid and Carboximidoic acid sary. (h) Cyclohehexaneethanol and Cyclohexethanol (i) Neo-pentane and Neopentane (i) Dibenz[b,e]oxepine and Dibenzo[b,e]oxepine (ii) Isopropanol and Propan-2-ol (j) Benzilmonoxime and Benzilmonooxime (iii) N-Acetylated aniline and N-acetylated aniline (k) Benzophenone and Benzphenone (iv) Spiro[5.4]decane and Spiro[4.5]decane (v) Methanoic acid and Methanoic-acid. 1.2 Answer these questions. (vi) Ethylethanoate and Ethyl ethanoate (a) In the following sets of combinations of locants, which (vii) Ethylmethyl ketone and Ethyl methyl ketone set will get preference in numbering the carbon atoms of (viii) Styrene oxide and Stryreneoxide a chain. (ix) Biphenyl and Diphenyl

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(x) Bis-2-chloromethylamine and Bis-(2-chloromethyl) (b) Draw the structures of the following compounds. amine (i) Triapentafulvalene (iv) Benzo[8]annulene (xi) (R)-Lactic acid and R-Lactic acid (ii) Azulene (v) 6[Annulene] (iii) 14[Annulene] 1.3 Give structures to demonstrate the following ways of naming organic compounds. 1.6 Give the IUPAC names of the following compounds.

(a) Trivial name (a) H3CCH3 (b) Semi-trivial name CH C CH CH2 CH2 CH3 (c) Fusion name (d) Substitutive name (b) H CCH (e) Replacement name 3 3 (f) Conjunctive name CH C CH CH2 CH CH2 (g) Radicofunctional name (h) Additive name (c) CH3 (i) Subtractive name CH3 CH CH CH2 CH2 CH3 (j) Hantzsch–Widman name of hetercycles 1.4 Give the IUPAC names of the following compounds.

(a) CH3CH CHCHCH2CH CH2 (d) CH CH2 (b) CH2 CHCHCH CHCH CH 2 Press CCH CH CH CH (c) CH2 CCH 2 2 2

CH3[CH2]2CCH2CH2CHCH CH 2 (e) CH2

CH3 CCH

(d) CH3[CH2]3CCH2CH2CHCH CH 2

CH3 (f) CH2 CH2 CH2 CH3 CH3 (e) CH CH CH CHC CCHCH C CCH CH CH University 3 2 2 2 2 CH CH CH CH CH3 CH2 CH2 CH2 2 2 2 3

CH CH2 (g) (h) (f) CH3C CCHCH CHCH3

C(CH3)2CH2CH2CH3 Naphthalene Naphthacene (g) CH3[CH2]4CH2 C CH2[CHOxford2]4CH3 (ortho-fused) (ortho-fused) CH3[CH2]2CH2 C(CH3)2 (i) (h) CH2 C C C CH2

CH CH2

(i) CH3CH2CH2C CHCH3 Chrysene 1.5 Answer these questions on structures. (ortho-fused) (a) Give the IUPAC names of the following compounds. 1.7 Give the trivial names of the following compounds. (i) (ii) CHCH3 (a) (b)

CH3

(iii) CH2CH2CH3 (iv) CH3 (c) (d)

CH3

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(e) (f) (iv) (v) (vi)

(vii)

(g) (h) (b) Give the IUPAC names of the following spiro hydrocarbons. Show the numbering of the carbon atoms. (i) (j) (i) (iv)

(ii) (v) (k)

(iii) (vi)

1.10 Identify the correct numbering of the following pairs of 1.8 Identify the correct numbering of the carbon atoms of the spiro compounds and give its IUPAC names.

following sets of compounds. 7 8 1 (a) H CCH CH (a) 10 1 (b) 13 1 2 2 2 14 4Press2 9 2 12 2 C CH2 and 3 11 8 3 H2C CH2 CH 10 56 3 2 4 7 4 9 5 6 5 6 5 7 1 H2C CH2 8 6 CH2 4 2 10 1 C CH (c) 10a (d) 8 9 1 2 9 2 8a 9a 7 2 H2C CH2 CH2 7 8 3 8a 3 6 3 8 4b 4a 3a 5 4 (b) 8 9 1 CH2 CH2 CH2 7 4 University7 4 2 5a C 6 5 H2C CH2 and

1 2 CH2 CH2 CH2 (e) 9 1 (f) 6 5 3 9a 9b 8 2 8a 2a 8 3 6 5 1 7 3 CH2 CH2 CH2 5b 4a 7 4 2 6 5 4 7 5a 4 6 5 H2C C CH2

CH2 CH2 CH2 (g) 2 Oxford(h) 8 8 9 3 8a 1 3 7 1 8a 3a 6a 1.11 Answer these questions on IUPAC names and struc- 2 4 6 8 2a tures. 5 3 7 5a 5 3a (a) Give the structure of the following compounds. 6 4 (i) 1,1′-Bicyclopentadienylidene 8 1 (ii) Bi(cyclopentylidene) (i) 8a 7 2 (iii) Biphenyl 6a 3 (iv) Tercyclopropane 6 3a (b) Give the structures of alternate acylic and cyclic hydro- 5 4a 4 carbons and non-alternate cyclic hydrocarbons and men- 1.9 Answer these questions on the naming of structures. tion the necessary rules for such definitions. (c) Give the IUPAC names of the following hetercyclic spiro (a) Number the carbons and give the correct name of each of compounds. the following bridged hydrocarbons. (i) O (ii) O (i) (ii) (iii) N H

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(iii) (iv) (d) 3-(carboxymethyl)heptanedioic acid HN O (e) Biphenyl-3-carboxylic acid (f) Naphthalene-1,3,5-tricarboxylic acid (g) o-(2-Oxobutyl)benzoic acid (h) p-Benzoylbenzoic acid 1.12 Draw the structures of the following compounds. (i) 4-Methylbenzene-1,3-disulphonic acid (a) Perchloro(2-methylpentane) (b) 2-(Hydroxymethyl)heptane-1,6-diol 1.15 Give the IUPAC names of the following compounds. (c) Aluminium tri(2-propanolate) (a) O (d) Ethoxyethylene HOOC C COOH (e) Bis(2-bromoethyl) ether (f) 2,2′-Oxydiethanol (g) 3-Formylhept-2-enedial (b) COOH (h) 3-Vinylhept-2-en-6-ynal O (i) Pyridine-2-carbaldehyde C COOH (j) Benzenecarbothialdehyde O (k) Benzenehexol

1.13 Give the IUPAC names of the following compounds. (c) OH (d) CH3 OH C O O CH3 CH2 CH (a) OCH CH3 OCH2CH3 CH3 CH2 C CH2 C CH2 CH2 CH3 Press3 O O O (e) O

(b) CH3 C CH2 C CH2 CH2 C CH3 O C CH3 CH3 CH2 CH O O C CH3

O (f) O (d) CH2 CH C CH2 CH CH CH3 O C CH3 O O UniversityCH O C C6H5 (e) CH3 C CH C CH3 O CH2 CH CH2

(g) CH2 COOH O O

(f) CH2 C C CH2 C CH3 CH CH CH Oxford 2 2 3 HOOC CH2 CH2 COOH

CH2 COOH H2C O (h)

(g) CH3 CH2 CH2 C C CH3

O O HOOC CH2 CH2 COOH

(h) CH3 C CH2 C CH CH CH3 (i) O (j) O O C OOH C OOH O HO C H H (i) CH2 CH CCCH (k) COOH (l) COOH 1.14 Draw the structures of the following compounds. O HOOC O (a) Hepta-2,5-dienoic acid (b) Hex-2-en-4-ynedioic acid (c) Pent-4-en-2-ynoic acid CHO CHO

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O (g) HCH3 (h) OMe (m) D OH H2N C CH2 CH2 CH2 CH2 CH2 CH2 COOH C C DT (n) D D CH3CH2 CH3 D N N 14 CH D CH3 CH3CH2 (i) (j) 2 CH3CD2CH2CH3 H OH (o) CH T HO NH NH2 2

(k) CD3CN (l) DO CH2 CH2 OD (p) HOOC (q) + − N N Cl D = Deuterium, T = Tritium

HO NH NH2 1.17 Give the method of numbering the carbon atoms in the following compounds.

(r) + − (a) (b) OH N N BF4 O H

O O NH H H Press O (s) HO N C N D-Glucaro-1,4 : 6,3-dilactone Morphinan

1.16 Give the IUPAC names of the following isotopically (c) H labelled compounds. O CH2OH O

D CH COOD DCN H (a) (b) 3 (c) 3 HO OMe D D OH H H H Methyl b-D-xylo-Hexopyranoside-4-ulose D D University D 1.18 Draw the Fischer projection formula of (a) 4-O-a-D-Glu- copyranosyl-a-D-glucopyranose and Haworth structure 18 (d) D (e) (f) CH3 of (b) b-D-Galactopyranosyl(1→4)-a-D-glucopyranose. CH3 O D CH CH OH OHH 2 1.19 Draw the structures of (a) [(Z,Z,Z,Z)-Eicosa-5,8,11,14- DH T tetraenoic acid] and (Z)-Octadec-9-enoic acid. What are the OxfordCH 3 trivial names of these two compounds?

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