SCH 4U – Chapter 1.8 Amines and Amides Amines are hydrocarbon derivatives that contain a nitrogen atom bonded to at least one carbon atom although it may be bonded to up to 3 carbon atoms. Amines can be thought of as ammonia with one, two or all three of its hydrogens substituted by alkyl groups. AmmoniaPrimary amine (1˚) Secondary amine (2˚) Tertiary amine (3˚) methylaminedimethylaminetrimethylamine

Amines widely occur in all living organisms. When organisms decompose large and complex molecules such as proteins are broken down to simpler organic compounds called amines. Many nitrogen compounds have an unpleasant odour. Trimethylamine is partially responsible for the distinctive odour of fish. Amines are organic bases that can be neutralized by acids such as lemon juice Other examples of amines include; putrescine, and cadaverine. Amines are components of important biological molecules. Proteins are made from amino acids. Andrenaline is a complex amine involved in increasing breathing and heart rate during times of stress.

Adrenaline Putrescine (1,5 - diaminopentane) Cadaverine (1,4 - diaminobutane)

Amino Acids The type of amino acid depends on the nature of the R group side chain. Example: lysine, glycine, alanine, argininine, etc.

Naming Amines: According to IUPAC amines are nitrogen derivatives of an alkane. CH 3 NH 2 - aminomethane Alternately, they can be named as alkyl derivatives ammonia. CH 3 NH 2 - methylamine Molecules with 2 amino groups are called diamines. The IUPAC name for the 2˚ and 3˚ amines include the N-prefix to show the substituted groups on the amine. A convenient naming alternative uses the names derived from ammonia. The alkyl groups are listed as substituting the H atoms in ammonia.

ethylmethylaminetrimethylamine (N-methyl-1-aminoethane) (N,N –dimethylaminomethane)

1-aminobutane 3-aminohexane N-methyl-1-aminobutane N,N – dimethylamino methane butylamine 3-hexylamine butylmethylamine trimethylamine 1-aminobutane3-aminohexaneN-methyl-1- aminobutane N,N – dimethylamino methane butylamine3-hexylaminebutylmethylaminetrimethylamine Draw structural formulas for each of the following amines

Write two names for the following compounds and indicate if they are 1˚, 2˚, or 3˚ amines a) b)

Draw a structural diagram for each of the following compounds: a)2-chloro – N,N – dimethyl -4-aminohexane b)A tertiary amine with 4 carbon atoms.

Properties of Amines: Primary and secondary amines are very polar due to the N-H bond which allows them to H-bond with each other. Tertiary amines do not have N-H bonds and can’t H-bond. Higher boiling and melting points than similar sized ethers and alkanes. Smaller amines are soluble in water. N-C and N-H bonds are more polar. Amine share a lower boiling point than alcohols of similar size because N-H bonds are less polar than O-H bonds. Smaller members have characteristic fishy odours.

Preparing Amines: Primary amines can be prepared by reacting ammonia with an alkyl halide. ethyl iodide + ammonia → ethylamine + hydrogen iodide CH 3 CH 2 -I+ NH 3 → CH 3 CH 2 NH 2 +HI Secondary amines can be prepared by reacting a primary amine further with the alkyl halide. ethyl iodide + ethylamine → diethylamine + hydrogen iodide CH 3 CH 2 -I CH 3 CH 2 NH 2 → CH 3 CH 2 NHCH 2 CH 3 + HI

Tertiary amines can be prepared by further reaction with an alkyl halide ethyl iodide + diethylamine → triethylamine + hydrogen iodide Whenever these reactions are carried out, a mixture of primary secondary and tertiary amines result. The different types of amines can be isolated based on boiling points by fractional distillation or more specific synthesis methods can be used.

Amides: An amide is a hydrocarbon that contains a carbonyl group bonded to a nitrogen atom Similar to esters but the –N atom replaces the O atom in the chain of an ester. Amides consist of carbonyl groups attached to an N atom. Amides are the backbone of all protein molecules. In proteins amide bonds are called peptides. ester amide RR Note that the O attached to The carbonyl group has been replaced by an N

Note that proteins consist of a series of amide bonds repeated over and over again to form a polypeptide.

The pain killer acetaminophen (Tylenol) is an amide. Penicillin is a complex amide. Most commercial uses of amides are in polymers such as nylon and polyacrylamide.

Properties of Amides: Amides have a polar carbonyl group and amides with at least one –NH group can form strong hydrogen bonds among themselves. Higher boiling points than their corresponding hydrocarbon derivatives. In terms of their polarity: amide >acid>alcohol>ketone = aldehyde>amine>ester>ether>alkane Amides are weak bases that are insoluble in water. low molecular weight amides are slightly soluble. Can be hydrolyzed in acidic or basic conditions to produce a carboxylic acid and an amine.

Naming and Preparing Amides: Carboxylic acids react with ammonia or primary or secondary amines to produce amides. These are condensation reactions and water is formed. Example: ethanoic acid + ammonia → ethanamide + water Tertiary amines do not undergo condensation reactions, they lack the extra H atoms needed to make water. Amides can also be made with primary amines (R – NH 2 ) and carboxylic acids by condensation reactions. NH 3 H2OH2O

butanoic acid + methylamine → N-methylbutanamide + water amides end in –amide. The first part of an amide’s name comes from the amine. In the example above the amine is methylamine, so the amide’s name begins with methyl. The second part of the name derives from the acid. In the example above the acid is butanoic acid. The -oic of the acid of the acid name is dropped and replaced with –amide. If one or more alkyl groups is attached to the N atom the upper case N is used to clarify the location. H2OH2O

Example: N-ethyl –N-methyl butanamide

Write the IUPAC names for the following compounds: a) b)

Drawing Amides Draw structures for the following compounds: a)ethanamide (acetamide) b)N-methyl-N-isopropylbutanamide

Homework: 1.Read pg. 69 – 79 2.Page 72 # 2 – 3 3.Page 76 # Page 78 # Page 78 # 1 - 7