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Flashcards in 26 Deck (18):
1

How to oxidise an aldehyde?

Aldehyde + [O] = carboxylic acid
K2Cr2O7/H2SO4 catalyst, reflux

2

Why can't ketones undergo oxidation?

Lack of hydrogen

3

What reaction do ketones and aldehydes undergo?

Nucleophilic addition (polar C=O)

4

How to distinguish between an aldehyde and a ketone? (Reaction)

Tollen's reagent (silver nitrate solution in aqueous NH3) Ag+(aq) + e- = Ag(s)
An aldehyde would form a silver mirror
A ketone would not react because they cannot be oxidised

5

How to test for the carbonyl group?

Brady's reagent (2,4-dinitrophenylhydrazine)
Aldehyde/ketone + Brady's reagent = 2,4-dinitrophenylhydrazone

6

How to reduce an aldehyde?

NaBH4/H2O
Aldehyde + 2[H] = primary alcohol

7

How to reduce a ketone?

NaBH4/H2O
Ketone + 2[H] = secondary alcohol

8

Which carbonyl group has a higher boiling point?

Ketones

9

Solubility of carboxylic acids

Soluble in water, C=O and O-H bonds are polar which forms hydrogen bonds (up to 4)
Solubility decreases as carbon chain increases

10

Carboxylic acid + metal

Carboxylate salt + H2

11

Carboxylic acid + base

Carboxylate salt + H2O (+ CO2 if carbonate base)

12

How to test for the carboxylate group?

React with a carbonate, observe effervescence

13

How to form an ester?

Carboxylic acid + alcohol = ester + H2O (esterification)
Acyl chloride + alcohol = ester + Hal
Acid anhydride + alcohol = ester + carboxylic acid

14

What is acid hydrolysis?

Reverse of esterification (heated under reflux)
Ester + H2O = carboxylic acid + alcohol
Dilute acid catalyst

15

What is alkaline hydrolysis?

Ester + OH- = carboxylate ion + alcohol (irreversible)

16

Preparation of acyl chlorides

Carboxylic acid + SOCl2 (thionyl chloride) = acyl chloride + SO2(g) + HCl(g)
Carried out in a fume cupboard

17

Forming carboxylic acids from acyl chlorides

Acyl chloride + H2O = carboxylic acid + HCl

18

Forming amides

Acyl chloride + ammonia = primary amide + NH4Cl
Acyl chloride + primary amine = secondary amide + alkyl-ammonium-Cl