6.1.2 & 6.1.3 - Carbonyls, Carboxylic acids, and Derivatives

Question 1

formula for aldehyde oxidation

Answer 1

aldehyde + [O] –> carboxylic acid

Question 2

conditions for aldehyde oxidation

Answer 2

acidified potassium dichromate
heat under reflux

Question 3

observations for oxidation of aldehydes

Answer 3

colour change: orange to green

Question 4

can ketones be oxidised?

Answer 4

no

Question 5

formula for the reduction of an aldehyde

Answer 5

aldehyde + 2[H] —> primary alcohol

Question 6

formula for the reduction of an ketone

Answer 6

ketone + 2[H] –> secondary alcohol

Question 7

conditions for reduction of ketones and aldehydes

Answer 7

H2O/NaBH4

Question 8

by what mechanism do carbonyls reduce to alcohols

Answer 8

nucleophilic addition

Question 9

examples of nucleophiles for reduction of carbonyls

Answer 9

H- (from NaBH4)
CN- (from HCN)

Question 10

how do we make HCN

Answer 10

in situ with NaCN/H+
as HCN is a dangerous and poisonous liquid

Question 11

2,4-DNP/ Brady’s reagent

Answer 11

Tests for the presence of a carbonyl group
C=O
positive test: yellow/ orange precipitate

Question 12

how to identify the derivative after confirming the presence of a carbonyl group with Brady’s reagent

Answer 12

• purify derivative product by filtration and recrystallisation
• compare the melting point to known values to identify the compound

Question 13

Tollen’s reagent

Answer 13

Tests for the presence of an aldehyde
positive test: silver mirror

Question 14

what does tollen’s act as for an aldehyde

Answer 14

oxidising agent

Question 15

equation for tollen’s with aldehyde

Answer 15

aldehyde + [O] –> carboxylic acid

Ag+(aq) + e- —> Ag(s) [reduced]

Question 16

how to prepare tollen’s reagent

Answer 16

• CLEAN test tube
• add aqueous silver nitrate
• add aqueous sodium hydroxide until a brown precipitate (Ag2O) forms
• add dilute aqueous ammonia until the precipitate dissolves

Question 17

how are carboxylic acids water soluble

Answer 17

contain polar C=O and O-H groups allowing them to form hydrogen bonds with water molecules

Question 18

how does solubility of carboxylic acids change

Answer 18

longer carbon chain
less soluble carboxylic acid

Question 19

test for carboxylic acids

Answer 19

react with a carbonate
effervescence
test the gas produced by bubbling through limewater
positive test: Turns cloudy (CO2)

Question 20

esterification of COOH and alcohols

Answer 20

carboxylic acid + alcohol ⇌ ester + water

Question 21

conditions for esterification of COOH and alcohols

Answer 21

concentrated strong acid catalyst (H2SO4)
heat

Question 22

esterification of acid anhydride and alcohol

Answer 22

acid anhydride + alcohol –> ester + carboxylic acid

Question 23

conditions for acid hydrolysis of esters

Answer 23

dilute strong acid (H2SO4)
reflux

Question 24

equation for acid hydrolysis of esters

Answer 24

ester + water ⇌ carboxylic acid + alcohol

Question 25

conditions for saponification (alkali hydrolysis)

Answer 25

reflux aqueous hydroxide ions

Question 26

equation for base hydrolysis of esters

Answer 26

ester + OH- --> carboxylate ion + alcohol

Question 27

how can acyl chlorides be made from carboxylic acids

Answer 27

carboxylic acid + thionyl chloride --> acyl chloride + SO2(g) + HCL(g)

Question 28

what is thionyl chloride

Answer 28

SOCl2

Question 29

esterification of acyl chlorides

Answer 29

acyl chloride + alcohol --> ester + HCl

Question 30

why doesnt the esterification of acyl chlorides and acid anhydrides require a catalyst

Answer 30

theyre more reactive than carboxylic acids

Question 31

order of reactivity of COOH derivatives from least to most

Answer 31

RCOOH acid anhydride acyl chloride

Question 32

why cant carboxylic acids undergo esterification with phenol

Answer 32

theyre not reactive enough

Question 33

the equation for formation of carboxylic acids from acyl chlorides

Answer 33

acyl chloride + water --> carboxylic acid + HCl