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Home , Carbonyl group

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Why is this so important?  Over and over again, you will be asked to do Identifying Functional reactions, the details to which you will receive in lecture and via your textbook. For each reaction, Groups reagents will be used to convert one into another. The Key to Survival  If you cannot recognize what a functional group looks like, it will be impossible for you to do this process… The facts that you need to remember won’t mean anything… And you won’t be able to draw the right pieces on your molecules…

What is a “functional group”? Why is this necessary?  A functional group is any collection of bonded  Knowing your functional groups will make your life that are not simply sp3C-sp3C (your basic C- much easier when its time for you to identify them C single bond) or sp3C-H. in a lab assignment () or when you have to remember facts, like the reaction  The only family in that has only of an with water and a catalyst forms an C-C and C-H single bonds is the family and . If you don’t know what an alkene or they are recognized by their LACK of functional alcohol looks like, this class is impossible. groups (or functionality, if you will).

Alkanes  In order to identify the functional groups, you have to know what sorts of bonds are in each kind of  Just for comparison’s sake, let’s start with functional group. something that has no functional groups. have C-C single bonds and C-H bonds and all the  We’ll scroll through the functional groups, one at a are sp3 hybridized. All of the following time and compare and contrast, until you showing below are alkanes. Those in rings are still (hopefully) get used to what they look like. alkanes, and are referred to as cycloalkanes but  Just remember, organic professors are devious – they don’t have functional groups either. and sometimes the mere change from a zig-zag structure to a condensed formula can entirely confuse you!

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Alkyl Halides  The halide is identified by the presence of an  An alkene has a C=C in its structure. This C=C sp3C-X bond in the structure. Halides can be might have groups or hydrogen atoms fluorine, chlorine, bromine or iodine (X=F, Cl, Br or attached. Each of the following are alkenes: I). Each of the following has an alkyl halide (or more specifically, alkyl bromide, alkyl chloride, alkyl iodide, if you wish):

Br I

Cl

Alkynes  An has a triple bond between two carbon  An alkyne has a triple bond between two carbon atoms in its structure. Triple bond might have atoms in its structure. If there is one carbon group carbon groups on both or perhaps one carbon attached (and one hydrogen ), the functional group and one hydrogen atom attached (usually not group is still called an alkyne and we fine-tune the drawn!). If there are two carbon groups attached, identification by calling it a “terminal alkyne”: an “internal alkyne”. Note the linear structure, as should be the case for sp hybridized carbon atoms.

is the same as H

Arenes or Aromatic Rings  An arene or aromatic ring, for the purpose of this  The is identified by the presence of C-O-C introductory course, is a six-membered ring of bond in the structure. The carbon groups on the carbon atoms, with alternating double and single left and right side can be alkyl groups or aryl bonds. It can have up to six groups attached to it. groups but they cannot be carbonyls (C=O). Each of These may also be called “aryl” groups. The the following is an ether: following are examples of aromatic rings: O

O O

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Epoxides The  The is a specific type of ether functional  The amine functional group has a atom. group, and contains the C-O-C bond inside a three- The nitrogen atom can have two hydrogen atoms

membered ring. Each of the following is an (NH2), one hydrogen atom and one carbon group epoxide: (NHR) or two carbon groups (NHR2 or NHRR’). The carbon groups CANNOT be C=O (carbonyl). Note O O how each of the following has a nitrogen: O

NH 2 N N H

What is what? What is what?  One of the following is an alkyl halide, one is an  One of the following is an alkyl halide, one is an ether and one is an amine. Identify which is which. ether and one is an amine. The ether has the surrounded by carbons. The alkyl halide H O N has the HALIDE and the amine has the nitrogen

Br atom. H N O Br ether alkyl halide amine

What is what? What is what?  One of the following is an alkene, one is a terminal  One of the following is an alkene (with a double alkyne and one is an internal alkyne. Assign the bond) and the others have triple bonds. They are structures to their type of functional group. alkynes. The alkyne in the middle of the chain is the internal alkyne and the other, at the end of the chain, is the terminal alkyne.

terminal alkyne alkene internal alkyne

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The Carbonyl Compounds The Carbonyl Compounds  There are a whole series of compounds that  The first compound has OH on the left and C on the contain the carbonyl group, C=O. The classification right. of the functional group is dependent upon what is attached to either side of the carbon atom of the  The second compound has C on the left and C on carbon group. Identify what is attached to the left the right. and right sides of each of the following:  The third compound has C on the left and H on the right. O O O O O O HO H HO C C C C H

The (NOT KEYTONE) The  The ketone functional group has a carbonyl group,  The aldehyde functional group has a carbonyl C=O, surrounded by carbon groups on both sides. group, C=O, surrounded by a carbon group on one They can be alkyl groups or aromatic rings. The side and a H atom on the other. The carbon group condensed formula for a ketone group is –C(O)-. can be alkyl or aromatic. The condensed formula Note how each of the following has carbon groups for an aldehyde is –CHO. Note how each of the on both the left and the right: following has a carbon group on one side and a

O O hydrogen atom on the other:

O O O H H H O

Can you tell them apart? Can you tell them apart?  Which of the following is the aldehyde and which is  The compound on the left is the aldehyde the ketone? functional group (see the H on the right of the carbonyl?) and the compound on the right is the O O ketone (two carbon groups attached). H O O

C H C C

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The Carboxylic Can you tell them apart?  The functional group has a carbonyl  Which of the following is the aldehyde and which is group, C=O, surrounded by a carbon group on one the carboxylic acid? side and a hydroxyl group, OH, on the other. The

carbon group can be alkyl or aromatic. Note how O O each of the following has a carbon group on one H HO side and an –OH on the other:

O O O OH OH HO

Can you tell them apart? Can you tell them apart?  The compound on the left is the aldehyde  Identify which of the following is the carboxylic functional group (see the H on the right of the acid, aldehyde and ketone: carbonyl?) and the compound on the right is the carboxylic acid (carbon on right, OH on left). O O HO

O H O O

C H HO C

Can you tell them apart? The (NOT ESTHER)  Identify what’s on either side of the carbonyls:  The ester functional group has a carbonyl group, C=O, surrounded by a carbon group on one side and an OR’ group on the other. Either carbon O O HO C group, attached to the C=O or on the O atom, can H C C C O be alkyl or aromatic. Note how each of the following has a carbon group on one side and an ketone aldehyde carboxylic acid OR on the other:

O O O

O O O

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Can you tell them apart? Can you tell them apart?  Identify which of the following is the ketone and  Identify what’s on either side of the carbonyls: which is the ester?

O O O O C O C C O ester ketone

Can you tell them apart? Can you tell them apart?  Note the difference between an ester and an ether.  Does the following molecule contain an ester or an have an OR group attached to a carbonyl. ether? Ethers do not. O

O O O O ester ether

 These are the two most confused functional groups!

Can you tell them apart? Can you tell them apart?  With the OR group on the C=O, this is an ester.  With the OR group NOT on the C=O, there is not an ester in this molecule. Notice that this has TWO O different functional groups, a ketone on the left and O ether on the right.

ketone O C C  What about this molecule? Does it have an ester? C C O ether O

O

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The Acid Halide The Acid Anhydride  The acid halide functional group has a carbonyl  The acid anhydride functional group has two group, C=O, surrounded by a carbon group on one carbonyl groups, C=O, surrounding a central side and an –X atom on the other. X is typically a oxygen atom, and carbon groups on the other chloride or bromide. Note how each of the sides of the carbonyls. The carbon groups can be following has a carbon group on one side and an X the same or different. Note how each of the on the other: following has the two carbonyl groups, surrounding an oxygen atom: O O O O O O Cl Br O O

Can you tell them apart? Can you tell them apart?  Which is an ester and which is an acid anhydride?  Note the identifying characteristic of the double carbonyl in an acid anhydride. An ester only has one carbonyl (C=O). O O O

O O O O O

O O acid anhydride ester

Can you tell them apart? Can you tell them apart?  Which is an alkyl halide and which is an acid  The acid halide has its chloride or bromide halide? Both have halides (in this case, bromides) attached directly to a carbonyl group (C=O). The but what makes them different? alkyl halide has an sp3 hybridized carbon (alkyl group) attached to the halide. O

O Br Br

Br Br alkyl halide acid halide

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The Can you tell them apart?  The nitrile functional group has a C-N triple bond,  Which is an alkyne (terminal, internal) and which is and the nitrogen has a . Its commonly a nitrile? mistaken that the nitrogen atom has an undrawn hydrogen atom but that would be an error in both structure and thought. The condensed formula for a nitrile is –CN. Each of the following contain a N nitrile:

CH CH CH CN N 3 2 2 N

Can you tell them apart? The Nitro  The nitrile has a nitrogen atom in its triple bond.  The nitro functional group is typically drawn as one The other two are alkynes. The alkyne at the end of of two possible equivalent forms (they the chain is the terminal one (with a typically look alike), containing one N=O and one N-O. The

unseen hydrogen now shown) while the one in the condensed formula for a nitro group is NO2. Note center of the chain is the internal alkyne. how each of the following has a nitro group:

O NO N N 2 H O N terminal alkyne nitrile internal alkyne O 2

So there you go…  You have now seen all of the functional groups commonly encountered in organic chemistry. There are others lurking out there but if you know THESE, you are in really great shape… Now go try that problem set to double check yourself!

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