carboxylic acids and derivatives

Question 1

oxidation of aldehyde to produce a carboxylic acid

Answer 1

h2so4 and k2cr2o7
heat under reflux

CH3CHO + [O] —> CH3COOH

Question 2

full oxidation of a primary alcohol to produce a carboxylic acid

Answer 2

h2so4 and k2cr2o7
heat under reflux

CH3CH2OH + 2[O] —> CH3COOH + H2O

Question 3

hydrolysis of a nitrile to produce a carboxylic acid

Answer 3

dilute HCL
heat under reflux

CH3CN + 2H2O + HCl —> CH3COOH + NH4Cl

Question 4

hydrolysis of an amide

Answer 4

HCl catalyst
water

produces carboxylic acid and ammonia

Question 5

gringard reagent to produce a carboxylic acid

Answer 5

gringard reagent + CO2
dilute HCl catalyst

CH3CH2MgI + CO2 —> CH3CH2COOH + Mg(OH)I

Question 6

test for carboxylic acid with a carbonate

Answer 6

add a small quantity of carbonate to sample

collect gas into a test pipette and bubble through a small volume of fresh lime water

gas evolved turns limewater cloudy

Question 7

carboxylic acid + metal

Answer 7

salt + hydrogen

Question 8

carboxylic acid + alkali

Answer 8

salt + water

Question 9

carboxylic acid + carbonate

Answer 9

salt + water + carbon dioxide

Question 10

why are carboxylic acids acidic but alcohols (that also contain OH) are not

Answer 10

when a proton is lost a pi bond is formed over the COO- group
the negative charge is delocalised between the 3 atoms
this stabilises the carboxylate ion
alcohols do not have this delocalisation so do not readily lose a proton

Question 11

reducing carboxylic acids (to 1° alcohol)

Answer 11

LiAlH4
in dry ether

warm with dilute HCl (hydrolysis)

CH3COOH + 4[H] —> CH3CH2OH + H2O

Question 12

test for a carboxylic acid with sulphuric acid, ethanol and Na2CO3

Answer 12

add 1cm3 ethanol
2 drops conc sulphuric acid
warm in water bath
tip onto saturated solution of Na2CO3
smell cautiously

Question 13

formation of an acyl chloride

Answer 13

add PCl5 to a carboxylic acid
anhydrous conditions

—> R-COCl + POCl3 + HCl

Question 14

what are carboxylic acids reduced to

Answer 14

alcohols

Question 15

reduction of COOHs

Answer 15

LiAlH4
solution of dry ether
warming with dilute HCl

Question 16

acyl chloride with water

Answer 16

room temperature
forms carboxylic acid

Question 17

acyl chloride and alcohol

Answer 17

room temperature, anhydrous conditions
produces ester + HCl

Question 18

acyl chloride + conc ammonia

Answer 18

room temperature, anhydrous conditions
produces amide + HCl

Question 19

acyl chloride + amine

Answer 19

room temperature, anhydrous conditions
produces amide + HCl

Question 20

properties of esters (4)

Answer 20

volatile
low boiling points
soluble in organic solvents
immiscible in water

Question 21

how to name esters (and draw)

Answer 21

alcohol group first (propyl,ethyl etc)
then parent acid (ethanoate, propanoate etc)

eg ethyl propanoate

drawn other way round, alcohol at the end

Question 22

give the name of HCOOC2H5

Answer 22

ethyl methanoate

Question 23

give the name of C2H5COOCH3

Answer 23

methyl propanoate

Question 24

how to form an ester from COOH and alcohol

Answer 24

warm under reflux
few drops of H2SO4 catalyst
reversible reaction

Question 25

how to form an ester from an alcohol and an acyl chloride

Answer 25

room temperature anhydrous conditions

Question 26

why is the formation of estes better with acyl chloride reaction than COOH reaction

Answer 26

goes to completion (not reversible) doesn’t require heating

Question 27

define hydrolysis

Answer 27

chemical reaction in which water reacts with a compound to produce other compounds involves splitting of a bond and the addition of hydrogen cation and hydroxide anion from water

Question 28

hydrolysis (of ester) with water reaction

Answer 28

dilute acid catalyst produces carboxylic acid and alcohol

Question 29

2 products of the hydrolysis (of ester) with dilute alkali (eg NaOH) hydrolysis reaction

Answer 29

produces salt (eg sodium ethanoate) and alcohol

Question 30

how to draw a condensation polymer

Answer 30

set out molecules in A B A B format eliminate molecules of water between each end of each pair of molecules