Carboxylic Acids and Esters

Question 1

What is the functional group of Carboxylic Acids?

Answer 1

—-COOH

    O 
    | |  R --- C --- OH

R can be alkyl group or H

Question 2

What is the functional group of Esters?

Answer 2

—-COO—-

    O
    | | R --- C --- O ---R'

R’ has to be an alkyl group

Question 3

What is the general formula for Carboxylic Acids?

Answer 3

C n H 2n+1 COOH

Question 4

What is the general formula for Esters?

Answer 4

Cn H2n+1 COO Cn H2n+1

Question 5

What are 3 reactions of carboxylic acids?

Answer 5

1. Esterification
2. Reduction
3. Acting as acids

Question 6

How do you form R - Xs from -COOHs?

Answer 6

add LiAlH4 (in dry ether)

Question 7

What is the equation for step 1 of RCOOH and LiAlH4?

Answer 7

R COOH + 2[H} —> R CHO + H2O

e.g. CH3COOH + 2[H] —> CH3CHO + H2O

Question 8

What is the equation for step 1 of RCOOH and LiAlH4?

Answer 8

R CHO + 2[H] —> R CH2OH

Question 9

What is the overall equation for the reduction RCOOH using LiAlH4?

Answer 9

R COOH + 4[H} —> R CH2OH + H2O

Question 10

What is the general equation for:

Carboxylic acid and metal?

Answer 10

Metal + RCOOH —> Salt + H2

                           Metal \_\_\_\_\_\_oate

e.g. Mg + RCOOH —> (RCOO)2 Mg + H2

Question 11

What is the general equation for:

Carboxylic acid and base?

Answer 11

Base + RCOOH —> Salt + H2O

e.g. NaOH            |
                    Metal \_\_\_\_\_\_oate

Question 12

What is the general equation for:

Carboxylic acid and carbonate?

Answer 12

Carbonate + Acid —> Salt + H2O + CO2

Question 13

What is the general equation for:

Esterification?

Answer 13

Alcohol + Carboxylic Acid

Question 14

What type of reaction is Esterification?

Answer 14

Condensation/Elimination

Question 15

How do you favour a forward reaction for Esterification?

Answer 15

Add a catalyst of concentrated H2SO4

H2SO4 dehydrates the reaction by pulling water out

Question 16

What is unexpected about the mp and bp of carboxylic acids and why?

Answer 16

higher than normal

polar nature of COOH causes H bonding

formation of dimers

Question 17

Where does the -thly and -oate parts come from when naming Esters?

Answer 17

• thyl: alcohol part
• oate: carboxylic acid part

R - COO|H + HO| - R’
O | (conc. H+ / heat)
| |
R - C - O - R’ + H2O

Question 18

Why do esters have a lower bp than correspounding carbonyl groups?

Answer 18

No H bonding

Question 19

What are some uses of esters?

Answer 19

Perfumes
Flavouring
Soaps

Esters have a distinct smell

Question 20

What are examples of naturally occurring esters?

Answer 20

Fats - solid at r.t

Oils - liquid at r.t

Question 21

What are the 2 types of hydrolysis of esters?

Answer 21

1. acid

2. base

Question 22

What do you add to catalyse the hydrolysis of esters?

Answer 22

1. H2O - dilute acid

2. NaOH - alkali

Question 23

What is the general equation for H2O/H+ + RCOOR’?

Answer 23

heat (reflux)

H2O + RCOOR’ ——–> RCOOH + HO-R’

Question 24

What is the general equation for NaOH + RCOOR’?

Answer 24

NaOH + RCOOR’ —-> HO-R’ + RCOO-Na+

distill ROH off