carbonyls and carboxylic acids

Question 1

why are aldehydes easy to oxidise?

Answer 1

as H atom is attached to the carbonyl group

Question 2

what happens to solubility of carboxylic acids as chain length increases?

Answer 2

decreases - as hydrocarbon tails ‘get in the way’, breaking h bonds between carbon and water, reducing solubility

Question 3

tollen’s test

Answer 3

Ag+ ins oxidise aldehyde, reducing Ag+ to Ag

Question 4

other name for Brady’s solution

Answer 4

2,4 - dinitrophenylhydrazine

Question 5

what is Brady’s test for

Answer 5

aldehyde and ketone

Question 6

positive Brady’s result

Answer 6

orange ppt.

Question 7

esterification

- conditions

Answer 7

reaction of alcohol with carboxylic acid to form and ester - in presence of H2SO4 (conc)

Question 8

hydrolysis of ester - product and conditions

Answer 8

• hot aqueous acid –> parent carb. acid

- hot aqueous alkali –> carboxylate ion

Question 9

acid hydrolysis

Answer 9

• reverse reaction of esterfication

Question 10

acid hydrolysis - conditions - - explain products

Answer 10

• ester refluxed with dilute aqueous acid
• broken down by water with acid acting as catalyst
• carb. acid and alcohol

Question 11

alkaline hydrolysis

Answer 11

ester refluxed with aqueous alkali

Question 12

products of alkaline hydrolysis

Answer 12

carboxylate ion and alcohol

Question 13

acyl chloride + alcohol =

Answer 13

HCl and ester

Question 14

acyl chloride + phenol =

Answer 14

HCl and ester

Question 15

acyl chloride + water =

Answer 15

HCl and carboxylic acid

Question 16

acyl chloride + ammonia =

Answer 16

ammonium chloride and primary Amide

Question 17

carbonyl functional group

Answer 17

C=O

Question 18

carboxylic acid + … –> acyl chloride

Answer 18

SOCl2

Question 19

acyl chloride + amine =

Answer 19

secondary amide

Question 20

ester functional group

Answer 20

COO

Question 21

advantages of using acid anhydrides instead of carboxylic acids to make esters

Answer 21

• position of equilibrium is further right so yield is higher
• no conc. acid catalyst required

Question 22

disadvantages of using acid anhydrides instead of carboxylic acids to make esters

Answer 22

• lower atom economy

Question 23

differences between acid and alkaline hydrolysis of esters

Answer 23

alkane hydrolysis produces carboxylate salt instead of carb acid

Question 24

naming esters

Answer 24

alcohol gives first part of name

carboxylic acid gives second part

Question 25

acyl chlorides formed form..

Answer 25

carboxylic acid and sulfonyl chloride

Question 26

how to form alcohol from aldehyde | - what type of alcohol formed?

Answer 26

warm w. aq. NaBH4 | - primary

Question 27

how to form alcohol from ketone | - what type of alcohol formed?

Answer 27

warm w. aq. NaBH4 | - secondary

Question 28

what chemicals are used in the lab provide HCN in a reaction?

Answer 28

NaCN and H2SO4

Question 29

what is useful about reaction between carbonyls and HCN

Answer 29

increases carbon chain length

Question 30

how to identify aldehyde or ketone by 2,4-DNP (Bradys)

Answer 30

- filter solution to collect yellow/range ppt. - solid then recrystallised to produce pure sample of crystals - melting point is measured and recorded - compare melting point to database to identify carbon compound

Question 31

maximum number of carbon atoms in a carboxylic acid which is soluble in water

Answer 31

4

Question 32

2 types of acid reactions of carboxylic acids

Answer 32

- redox with metals | - neutralisation with bases (eg. metal oxides, carbonates, alkalis)

Question 33

carb. acid + metal ->

Answer 33

H2 + Carboxylate salt

Question 34

carb. acid + metal oxide ->

Answer 34

salt + water

Question 35

carb. acid + alkali ->

Answer 35

salt + water

Question 36

carb. acid + carbonates ->

Answer 36

salt + water + carbon dioxide

Question 37

carb acid derivative?

Answer 37

compound which can he hydrolysed to form parent carb. acid

Question 38

common group of atoms all carb. acid derivatives share

Answer 38

acyl group R - C = O |

Question 39

carb acid derivatives (4)

Answer 39

- esters - acyl chlorides - acid anhydrides - amides

Question 40

product of alkaline hydrolysis with NaOH

Answer 40

sodium ethanoate salt

Question 41

method for esterification (from acid and alcohol)

Answer 41

- 2cm3 ethanol + 2cm3 propanoic acid -> boiling tube - add drops conc. H2SO4 - hot water bath at 80C - 5 mins - pour into beaker w. Na2CO3 (aq) [oily ester will float on surface]

Question 42

why does radical substitution result in mixture of products

Answer 42

- further substitution can occur | - substitution at different places along the chain