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Chemistry > Esters and Carboxylic Acids (NOT FINISHED) > Flashcards

Esters and Carboxylic Acids (NOT FINISHED) Flashcards

1
Q

Functional group of carboxylic acids

A

RCOOH.
C=O and C-OH

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2
Q

Why are the intermolecular forces between carboxylic acid molecules relatively strong

A

Due to the presence of two polar groups, C=O and C-OH

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3
Q

Why do carboxylic acids have a higher boiling point than alcohols

A

Each carboxylic acid molecule can form 2 hydrogen bonds but each alcohol molecule can only form one. More energy is needed to break the hydrogen bonds between carboxylic acid molecules.

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4
Q

Why are some carboxylic acid molecules soluble in water

A

They can form hydrogen bonds with water molecules because it has a polar -COOH group. The -COOH group can form hydrogen bonds with water molecules. ONLY CARBOXYLIC ACIDS 1 to 4 are soluble

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5
Q

Why is benzoic acid only slightly soluble in water

A

The -COOH group can form hydrogen bonds with water molecules. However, it is only slightly soluble because the benzene ring is non-polar

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6
Q

Describe the reaction, conditions and reagents needed to go from a nitrile to a carboxylic acid

A

Reaction : Acid hydrolysis
Reagent : Dilute HCl
Conditions : Heat under reflux

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7
Q

nitrile + water + hydrochloric acid =

A

Carboxylic acid + ammonium chloride

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8
Q

Are carboxylic acids strong or weak acids

A

Weak. They only partially dissociate in solution

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9
Q

How are carboxylate salts produced

A

Acid-base reactions

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10
Q

What are the reagents and conditions for acid-base reactions in the production of carboxylate salts

A

Reagent : AQEUOUS sodium carbonate/hydroxide
Conditions : Room temperature

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11
Q

propanoic acid + sodium carbonate =

A

sodium propanoate + water + carbon dioxide

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12
Q

What is the test for the -COOH group

A

Add aqueous sodium carbonate to the compound. Bubble the gas produced into limewater. Fizzing/effervescence is observed. The colourless gas (CO2) turns limewater cloudy

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13
Q

Describe esterification

A

When a carboxylic acid is heater under reflux with an alcohol in the presence of an acid catalyst such as conc sulfuric acid, an ester is formed

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14
Q

What do carboxylic acids do to carbonates even though they are weak acids

A

They liberate the CO2 from carbonates.

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15
Q

What type of reaction is it when esters are formed from the reaction between carboxylic acids and alcohols

A

Reversible reaction

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16
Q

Why is the yield of esters low when produced from reacting carboxylic acids and alcohols

A

It is a reversible reaction and results in an equilibrium therefore low yield

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17
Q

Reagents and conditions for esterification

A

Reagents: Alcohol and concentrated sulfuric acid
Conditions : Heat under reflux

18
Q

How to draw esters

A

Break the -OH off the carboxylic acid
Break the H off the -OH on the alcohol
Connect the O of the alcohol to the main C of the carboxylic acid.

19
Q

How to name esters

A

The alcohol part first and then the carboxylic acid part.
e,g, propyl ethanoate

20
Q

Functions of concentrated sulphuric acid in esterification

A

Acts as the catalyst for the reaction
Absorbs the water formed, driving the equilibrium to the right and increasing the yield of the ester

21
Q

Functional group for esters

A

-COOR
There is a C=O and and -OR attached to the same carbon

22
Q

Common uses of esters

A

In solvents
Plasticisers
Perfumes
Food flavourings

23
Q

Main use of polyesters

A

Clothing

24
Q

How can esters be produced by acyl chlorides

A

When acyl chloride reacts with an alcohol at room temperature an ester and HCl is formed.
This reaction is called Nucleophilic addition-elimination

25
Q

What is the advantage of making esters by reacting an acyl chloride with alcohol

A

The reaction goes to completion giving a higher yield of the ester

26
Q

What is produced in the acid hydrolysis of esters

A

A carboxylic acid and an alcohol

27
Q

Conditions and reagents for acid hydrolysis of esters

A

Conditions : Heat under reflux
Reagent: dilute HCl/H2SO4 - acts as catalyst

28
Q

ester + water ———->
<———-

A

Carboxylic acid + alcohol

29
Q

Describe what happens in acid hydrolysis of esters

A

Ester is heated with dilute HCl
C-O bond in ester is broken using water
Carboxylic acid and alcohol produced

30
Q

Describe what happens in alkaline hydrolysis of water

A

Ester is heated with aqueous NaOH/KOH
A carboxylate salt and an alcohol are formed

31
Q

Advantages of alkaline hydrolysis of esters

A

Reaction goes to completion giving a higher yield
Products are easier to separate. Alcohol formed can be distilled off.

32
Q

ester + NaOH ——->

A

carboxylate salt + alcohol

33
Q

How are soaps made

A

By the alkaline hydrolysis of fats and oils.
The sodium salts of the carboxylic acid and the alcohol, glycerol, are formed

34
Q

Trigylceride + NaOH =

A

Soap + glycerol

35
Q

What is the chemical name for glycerol

A

propane-1,2,3-triol

36
Q

What are the esters of glycerol / propane-1,2,3-triol

A

Vegetable oils and animal fats

37
Q

How do vegetable oils and animals fats produce soaps and glycerol

A

Through alkaline hydrolysis

38
Q

What is biodiesal

A

A mixture of methyl esters of long-chain carboxylic acids

39
Q

How is biodiesel produced

A

By reaction vegetable oils with methanol in the presence of a catalyst

40
Q

Describe esterification of acid anhydrides with alcohols

A

The bottom part of the acid anhydride which looks like a carboxylic acid (RCOO) breaks off. The H of the alcohol also breaks off.

This forms an ester and carboxylic acid

Chemistry (20 decks)

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