Carboxylic acids and derivatives Flashcards
1
Q
Carboxyl group
A
- Combination of a C=O and a -OH on the same C
- Weak acids compared with the mineral acids,
but they are more acidic than alcohols or phenols.
2
Q
Aliphatic acid
A
- Alkyl group bonded to the carboxyl
group
3
Q
Aromatic acid
A
- Aryl group bonded to the carboxyl group
4
Q
Carboxylic acid angles
A
- Sp2 hybrid carbonyl C atom is planar, with nearly trigonal bond angles
5
Q
Carboxylic acid in drugs
A
- Make carboxylic acid into a salt to increase the solubility
6
Q
Lactones
A
- Cyclical carboxylic acid
7
Q
Lactams
A
- Cyclical amides
8
Q
Carboxylic acid + amide
A
- Ammonium carboxylate salt
9
Q
Acid Halides
A
- Halide ions are excellent leaving group for nucleophile acyl substitution
- Acid chloride active form of carboxylic acid
- Carbonyl O and Cl makes it electrophilic
10
Q
Acid Anhydrides
A
- Anhydride forms into two molecules of acid
- Activated form of a carboxylic acid. Carboxylate group leaves (good leaving group)
11
Q
Synthesis of Carboxylic acids
A
- From alkyl halide Halide to a carboxylic acid conversion with an additional carbon atom with Grignard reagents
12
Q
Formation and hydrolysis of nitriles
A
Limited to halides and tosylates (OTs)
that are good SN2 electrophiles
13
Q
Carboxylate anion
A
- Weak base - can act as a nucleophile
14
Q
Ester formation
A
Prepared by reacting alkyl halide and a carboxylate
15
Q
Nucleophilic Acyl Substitution
A
One nucleophile replaces another on
the acyl (C=O) carbon atom
16
Q
Basic conditions hydrolysis of ester
Nucleophilic Acyl Substitution
A
- Hydroxide ion (strong nucleophile) adds to C=O, forming tetrahedral intermediate
- An alkoxide ion leaves, regenerating the C =O double bond and stabilises itself
- A fast, exothermic proton transfer drives the reaction to completion
17
Q
Nucleophilic Acyl Substitution Acid conditions Fisher Esterification
A
- Acid-catalysed addition of the alcohol to the carbonyl group
- Acid-catalysed dehydration
- Methods to convert carboxylic acids (COOH) to esters
18
Q
Acid chloride convert to ester
A
- Pyridine or other bases: neutralise the
HCl generated - Alcohols (especially tertiary alcohols) may
dehydrate under strongly acidic conditions
19
Q
Condensation of acid with amines
A
- Carboxylic acid + amine
- Formation of ammonium carboxylate salt (poor electrophile) O- and NH3+R (Not nucleophile)
- Heat above 100 degrees drives off the water forcing reaction to complete NHR and H2O
20
Q
Acid chloride reaction with ammonium or amides
A
- Carboxylic acid to acide chloride to amide
- Addition of NaOH prevents HCL protonating the amine
21
Q
Halide ions
A
- Good leaving groups for nucleophilc acyl subsitution
- Acid chloride activated from carboxylic acid
- Carbonyl O and Cl make acyl strongly electrophilic
22
Q
Thyonyl chloride (SOCl2) or oxylate chloride (COCl2)
A
- Best reagent to convert Carboxylic acid to Acyl chloride
- Form gaseous byproduct SO2
23
Q
Carboxylic acid + acid chloride
A
Acid anhydride and HCl
24
Q
Carboxylic acid to primary alcohol
A
- Carboxylic acid to Acyl chloride to primary alcohol via LiAlH
- Alderhyde is more reactive compared to carboxylic acids
- OH is the nucleophile of carboxylic acid
25
Activated forms of the carboxylic acid
- Ester
- Amide
- Nitriles
26
Inactivated forms of carboxylic acid
- Acyl halide
- Anhydride
27
Primary amide
- CONH2 there are no alkyl groups
28
Secondary amide or N substituted amide
- Has one alkyl group attached to the nitrogen
- CONHR
29
Tertiary amide or N, N substitued amide
- Has two alkyl group attached to the nitrogen
- CONR2
30
Lactams
Cyclic amino acids + H2O
31
Nitriles
- Contain CN group
- Addition of H2O and H+ or OH- to a nitrile
- Formation of an amine with H2O and H+ forms carboxylic acid
32
Carboxylic acid to nitriles
- NH3 and heat CONH2
- Addition of POCl3 is -CN
- CN bond angle 180 and Sp hybridised
33
Anhydryide +H2O
- Formation of two carboxylic acids
34
Addition of nucleophile to acid anhydride
- Nucleophile attached to carbonyl and acyl chloride
35
Nucleophilic acyl substitution
- One nucleophile replaces another on acyl carbon atom forming tetrahedral intermediate
- Addition elimination of the leaving group regenerate carbonyl
36
Favourable reaction with acids
- Convert more reactive acid derivative to less reactive depending on structure and attacking nucleophile
- (Low) Carboxylate, Amide, Ester and Acid chloride (High)
- Strong base not good leaving group
