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Carboxylic acids and their derivatives. Structure. Structure of derivatives. acyl halide. anhydride. acid halide. ester. amide. The acyl group. Nomenclature. HCO 2 H formic acid (from Latin formica , ant). CH 3 CO 2 H acetic acid (from Latin acetum , vinegar)

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structure of derivatives
Structure of derivatives

acyl halide

anhydride

acid halide

ester

amide

nomenclature
Nomenclature

HCO2H formic acid (from Latin formica, ant)

CH3CO2H acetic acid (from Latin acetum, vinegar)

CH3CH2CO2H propionic acid (from Greek protos, first and piôn, fat)

CH3(CH2)2CO2H butyric acid (from Latin butyrum, butter)

CH3(CH2)3CO2H valeric acid (valerian root)

CH3(CH2)4CO2H caproic acid (from Latin caper, goat)

CH3(CH2)6CO2H caprylic acid

CH3(CH2)8CO2H capric acid

nomenclature6
Nomenclature

-aminobutyric acid

nomenclature7
Nomenclature

-hydroxypropionic acid or lactic acid

isocaproic acid

aromatic acids
Aromatic acids

p-bromobenzoic acid

m-toluic acid

aldehydes non systematic names
Aldehydes - non-systematic names

form(ic acid)aldehyde

b-methylvaleraldehyde

iupac
IUPAC

CH3CH2CO2H

propanoic acid

(CH3)2CHCH2CH2CO2H

4-methylpentanoic acid

2-hydroxy-5-methyl-3-hexenoic acid

(CH3)2CHCH=CHCH(OH)CO2H

C-1

cyclic acids
Cyclic acids

Saturated cyclic acids are named as cycloalkanecarboxylic acids:

cis-2-methylcyclohexanecarboxylic acid

salts of carboxylic acids
Salts of carboxylic acids

sodium benzoate

(CH3CO2)2Ca calcium acetate or calcium ethanoate

nomenclature of acyl halides
Nomenclature of acyl halides

Change -ic acid to -yl halide

nomenclature of anhydrides
Nomenclature of anhydrides

change acid to anhydride

nomenclature of amides
Nomenclature of amides

change -icor -oic acid to -amide

nomenclature of esters
Nomenclature of esters

change -ic acidto name of alcohol group or phenol + -ate

physical properties
Physical properties

Intermolecular hydrogen bonding is very important.

In the solid and liquid states, carboxylic acids exist as dimers. Mp and bp values are far higher than the corresponding alcohols.

physical properties of acid derivatives
Physical properties of acid derivatives

Polar compounds: the acyl halides, anhydrides, and esters

have boiling points which are very similar to those of

aldehydes and ketones of equivalent molecular weight.

However, the amides.......

relative acidities
Relative acidities

Relative basicities

substituent effects
Substituent effects

CH3CO2H ClCH2CO2H Cl2CHCO2H Cl3CCO2H

Ka 1.76x10-5 136x10-5 5530x10-5 23200x10-5

HCO2H CH3CO2H CH3CH2CH2CO2H

Ka 17.7x10-5 1.76x10-5 1.52x10-5

salts of carboxylic acids26
Salts of carboxylic acids
  • crystalline, non-volatile, decompose on heating to 300 - 400C.
  • sodium, potassium and ammonium salts are all water soluble and insoluble in non-polar solvents.
salts of carboxylic acids27
Salts of carboxylic acids

water insoluble

water soluble

NB: Phenols do not react with bicarbonate.

carboxylation of grignard reagents34
Carboxylation of Grignard reagents

2,2-dimethylpropanoic acid

preparation of nitriles an s n 2 reaction
Preparation of nitriles - an SN2 reaction

CH3CH2CH2CH2Br + CN- CH3CH2CH2CH2CN

primary halide

(CH3)3CBr + CN- (CH3)2C=CH2 + HCN

nomenclature of nitriles
Nomenclature of nitriles

CH3CH2CN - 3 carbon chain

propane + nitrile = propanenitrile

propionic acid - ic acid + onitrile = propiononitrile

ethanenitrile

acetonitrile

CH3CN

pentanenitrile valeronitrile

CH3(CH2)3CN

reactivity of carboxylic acid derivatives nucleophilic addition elimination
Reactivity of carboxylic acid derivatives – nucleophilic addition - elimination

G = -OH, -X, -OOCR, -NH2, or -OR

Why?

reactivity of carboxylic acid derivatives
Reactivity of carboxylic acid derivatives

The ease of loss of the leaving group, G, depends on its

basicity:

G = HO-, X-, RCO2-, NH2-, or RO-

G = H-, R- ?

acid chlorides
acid chlorides

Use thionyl chloride (SOCl2), phosphorus trichloride (PCl3) or phosphorus pentachloride (PCl5).

reactions of acyl halides the rosemund reduction
Reactions of acyl halides - the Rosemund reduction

RCHO or ArCHO

A special catalyst is used: palladium on barium sulfate which has been deactivated (poisoned) with an amine such as quinoline.

preparation of other anhydrides
Preparation of other anhydrides

Nucleophilic substitution of an acyl halide with a carboxylate anion.

alcoholysis of anhydrides
Alcoholysis of anhydrides

+ CH3CO2H

methyl

acetate

reactions base hydrolysis
Reactions - base hydrolysis

rate = k[OH-][ester]

How can we prove that OH- attacks the acyl carbon and not the alkyl carbon?

predicted result for acyl oxygen bond breaking
Predicted result for acyl - oxygen bond breaking

So what happens when we perform the reaction?

(+)-2-butanol is obtained - [] = +13.8o

acyl - oxygen bond breaking occurs

a halocarboxylic acids94
a-Halocarboxylic acids

dicarboxylic acid

spectroscopy
Spectroscopy

IR:

C=O stretching ~ 1710 cm-1 (dimer), ~1760 cm-1 (monomer)

O-H stretching - broad range (3400 - 3600 cm-1)

NMR:

OH proton occurs in the region  = 9-13 ppm.