chapter seventeen amines and amides. chapter seventeen | slide 2 of 39 © royalty-free / corbis...

Chapter Chapter SeventeenSeventeen

Amines and Amides

Chapter Seventeen | Slide 2 of 39

© Royalty-Free / CORBIS

Amines and Amides

Parachutist with a parachute made of the polyamide nylon.


Nitrogen

• The four most abundant elements in organic compounds are carbon, hydrogen, oxygen, and nitrogen

Element Valence Electrons Bonds for an Octet

Carbon 4 4

Hydrogen 1 1

Oxygen 6 2

Nitrogen 5 3


• Organic compounds of nitrogen N• Classified as primary, secondary, tertiary• NH2 = amino group

CH3 CH3

CH3—NH2 CH3—NH CH3—N — CH3

______ _______ ________

Amines


Fig. 17.1 Classification of amines is related to the number of R groups attached to the nitrogen atom.

Amines and Amides cont’d


Naming Amines

• Classified as primary (RNH2), secondary (R2NH), or tertiary (R3N). Different than alcohols.

primary ROH

R

N

H

H

R

N

H

R

R

N

R

R

R OH R OH

R

R OH

R

Rsecondary ROH

tertiary ROH

primary amine secondary amine tertiary amine


Aniline, the simplest aromatic amine. Aromatic amines are generally toxic.



Naming Primary Amines

• Identify the parent chain: the longest chain of carbons to which the nitrogen is attached

• Replace the “-e” ending of the alkane name with “-amine”

• Number the parent chain from the end closest to the nitrogen atom

• Identify the position of the nitrogen atom with a number

• Identify any substituents and their locations


Name the Following Amines

2-propanamine

1,4-butanediamine or1,4-diaminobutane

cyclohexanamineNH2

NH2

NH2

H2N


Naming Secondary and Tertiary Amines

• Base name involves longest carbon chain attached to the nitrogen– Other groups attached to the nitrogen have “N-” in front of the

substituent names

N-ethyl-N-methyl-ethylamine

N-ethyl-N-methyl-cyclohexylamine

N

N


Amine-amine hydrogen bonding.



Low-molecular amines are soluble in water because of amine-water hydrogen bonding interactions.



Ammonium ion has a tetrahedral structure, as does the quaternary ammonium ion.



Fig. 17.8 Heterocyclic amines serve as “parent” molecules for more complex amine derivatives.




Methoxyamphetamine Isopreternol


• Like ammonia, amines act as weak __________ in water– _____________ are proton acceptors

• When amines react with water, the products are a hydroxide ion and a substituted ammonium ion– Substituted ammonium ion: an ammonium ion in which one

or more alkyl, cycloalkyl, or aryl groups have been substituted for hydrogen atoms

CH3NH2 + H2O CH3NH3+ + OH–

methylammonium hydroxide

Basicity of Amines

Treating an amine salt with a strong base regenerates the amine


Neutralization Forms Amine Salts

• Neutralization with _______ gives ammonium salt

CH3NH2 + HCl CH3NH3+ Cl–

methylammonium chloride

• Amine salts are named by replacing the “amine” part of the name with “ammonium” followed by the name of the negative ion


Properties of Amine Salts

• Amine salts are:– Solid at room temperature– Soluble in water and body fluids– The form used for drugs

CH3

OHN

+

CH3

H

HCl-

ON

+

CH3

CH3

H

Cl-

Ephedrine Hydrochloride Ephedrine HCl

Sudafed

Diphenhydramine hydrochloride Diphenhydramine HCl

Benadryl


Other Amine Salts

• Cocaine is sold illegally as an amine salt• Cocaine is reacted with NaOH to produce the free

amine form, known as “crack”

Cocaine Hydrochloride Cocaine (“free base”)

O

O CH3

H

O

O

N

CH3O

O CH3

H

O

O

N+

CH3H

Cl-


Amines vs. Amides

• Amides have carbonyl groups next to the nitrogen.• Amines have alkyl groups or hydrogens bonded to

the nitrogen.

R

N

R

RO

R2N Ramide amine


Classification of Amides

Classification depends on the number of alkyl groups connected to the amide nitrogen atom


Models of the simplest primary, secondary, and tertiary amides.



The high boiling point of amides are related to the numerous amide-amide hydrogen bonding possibilities that exist.



NH2

O

HN

N

N

O

O

NH2

NN

N

O

O

N

N

• Classify each as amine or amide.

amide

amine

amide

amine

amide

amine

amide

amide

amine

amine



←CC 17. 5


• Physiologically active nitrogen-containing compounds• Obtained from ____________• Used as anesthetics, antidepressants, and stimulants• Many are ______________

Alkaloids


Nicotine


Caffeine


Procaine


Preparations of Amines

• Amines can be prepared by adding an alkyl halide to ammonia in the presence of base

• Two step process: alkylation to produce the salt; reaction with NaOH to produce the amine

– NH3 + R-X R-NH3+Cl-

– R-NH3+Cl- + NaOH RNH2 + NaX + H2O


Preparation of Amines

– Ammonia + alkyl halide + NaOH primary amine

– Primary amine+ alkyl halide + NaOH secondary amine

– Secondary amine+ alkyl halide + NaOH tertiary amine

– tertiary amine + alkyl halide quaternary

ammonium salt


Alkylation Reactions

R' XH3N: + H2N R'

R' XH2RN: + HRN R'

R' XR3N: + R3N R'+

X-

R' XHR2N: + R2N R'


Preparation of Amides

• Amides are produced by reacting a carboxylic acid with ammonia or an amine (primary or secondary)– “Amidification Reactions”– Dehydration Reaction

+ +

H2OR

O

OHNH2 R

R

O

NH2


Amidification Reactions

• Ammonia + carboxylic acid primary amide

• Primary amine + carboxylic acid

secondary amide

• Secondary amine + carboxylic acid tertiary amide


Amides undergo

acid hydrolysis base hydrolysis

carboxylic acid salt of carboxylic acid

ammonium salt and an amine or

ammonia

Reactions of Amides


acid hydrolysis O

O HCl + H2O CH3COH + NH4+Cl–

CH3CNH2 O

NaOH

CH3CO– Na+ + NH3

base hydrolysis

Reactions of Amides

chapter seventeen amines and amides. chapter seventeen | slide 2 of 39 © royalty-free / corbis...

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