Carboxylic Acids and Esters Flashcards
What is the functional group of Carboxylic Acids?
—-COOH
O
| | R --- C --- OH
R can be alkyl group or H
What is the functional group of Esters?
—-COO—-
O
| | R --- C --- O ---R'
R’ has to be an alkyl group
What is the general formula for Carboxylic Acids?
C n H 2n+1 COOH
What is the general formula for Esters?
Cn H2n+1 COO Cn H2n+1
What are 3 reactions of carboxylic acids?
- Esterification
- Reduction
- Acting as acids
How do you form R - Xs from -COOHs?
add LiAlH4 (in dry ether)
What is the equation for step 1 of RCOOH and LiAlH4?
R COOH + 2[H} —> R CHO + H2O
e.g. CH3COOH + 2[H] —> CH3CHO + H2O
What is the equation for step 1 of RCOOH and LiAlH4?
R CHO + 2[H] —> R CH2OH
What is the overall equation for the reduction RCOOH using LiAlH4?
R COOH + 4[H} —> R CH2OH + H2O
What is the general equation for:
Carboxylic acid and metal?
Metal + RCOOH —> Salt + H2
Metal \_\_\_\_\_\_oate
e.g. Mg + RCOOH —> (RCOO)2 Mg + H2
What is the general equation for:
Carboxylic acid and base?
Base + RCOOH —> Salt + H2O
e.g. NaOH |
Metal \_\_\_\_\_\_oate
What is the general equation for:
Carboxylic acid and carbonate?
Carbonate + Acid —> Salt + H2O + CO2
What is the general equation for:
Esterification?
Alcohol + Carboxylic Acid
What type of reaction is Esterification?
Condensation/Elimination
How do you favour a forward reaction for Esterification?
Add a catalyst of concentrated H2SO4
H2SO4 dehydrates the reaction by pulling water out
What is unexpected about the mp and bp of carboxylic acids and why?
higher than normal
polar nature of COOH causes H bonding
formation of dimers
Where does the -thly and -oate parts come from when naming Esters?
- thyl: alcohol part
- oate: carboxylic acid part
R - COO|H + HO| - R’
O | (conc. H+ / heat)
| |
R - C - O - R’ + H2O
Why do esters have a lower bp than correspounding carbonyl groups?
No H bonding
What are some uses of esters?
Perfumes
Flavouring
Soaps
Esters have a distinct smell
What are examples of naturally occurring esters?
Fats - solid at r.t
Oils - liquid at r.t
What are the 2 types of hydrolysis of esters?
- acid
2. base
What do you add to catalyse the hydrolysis of esters?
- H2O - dilute acid
2. NaOH - alkali
What is the general equation for H2O/H+ + RCOOR’?
heat (reflux)
H2O + RCOOR’ ——–> RCOOH + HO-R’
What is the general equation for NaOH + RCOOR’?
NaOH + RCOOR’ —-> HO-R’ + RCOO-Na+
distill ROH off
