10: Carboxylic Acids And Their Derivatives Flashcards

(33 cards)

1
Q

Why do carboxylic acids have quite high boiling points

A

They can form hydrogen bonds

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2
Q

Why is the boiling point of a carboxylic acid higher than an alcohol

A
  • The O-H bond in a carboxylic acid is even more polar than in an alcohol because of the adjacent C=O group.
  • Carboxylics acids have a molecular structure that enables them to form more hydrogen bonds than simple alcohols
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3
Q

Are carboxylic acids soluble in water

A

Yes, especially smaller carboxylic acids

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4
Q

Why does the solubility of a carboxylic acid decrease when the molecule gets bigger

A

Only the O-H group can form hydgrogen bonds with water so if the rest of the molecule is large and non-polar then it will be less soluble

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5
Q

How to prepare a carboxylic acid

A

Oxidation of a primary alcohol or and aldehyde

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6
Q

What are the reagents and conditions for oxidation of a primary alcohol or aldehyde

A

Acidified potassium dichromate, heat and under reflux

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7
Q

Write alcohols, carboxylic acids and phenols in order of acidity

A

Alcohol (not acidic)

Phenols (very weakly acidic)

Carboxylic acids (weakly acidic)

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8
Q

What does carboxylic acid + metal produce

A

Salt + hydrogen

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9
Q

What does carboxylic acid + carbonate produce

A

Salt + carbon dioxide + water

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10
Q

What does carboxylic acid + alkali produce

A

Salt + water

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11
Q

What does carboxylic acid + ammonia produce

A

Ammonium salt

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12
Q

Can esters form hydrogen bonds

A

No

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13
Q

How to produce an ester

A

Carboxylic acid + alcohol —> ester + water

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14
Q

What is a condensation reaction

A

Two molecules are joined together to make a larger product molecule but a small molecule is eliminated in the process

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15
Q

What conditions are needed for esterification

A

Concentrated sulphuric acid catalyst and heat.

Works best with reflux

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16
Q

What is an acid anhydride

A

Compound formed by dehydration of carboxylic acids.

17
Q

What is the general formula for acid anhydrides

18
Q

How is an acid anhydride formed

A

two carboxylic acids bond together and eliminate the OH from one and the H from the -OH from the other carboxylic acid to form an acid anhydride and water

19
Q

What does acid anhydride + alcohol form

A

ester + carboxylic acid

20
Q

What are the advantages of using anhydrides rather than carboxylic acids for producing esters

A

Anhydrides are more reactive which means:

Milder conditions can be used,

The reaction is irreversible which means that a higher percentage yield can be achieved

21
Q

What does hydrolysis of an ester produce

A

carboxylic acid and alcohol

22
Q

Why would you not just use water for hydrolysis of an ester and what can you use instead

A

It is extremely slow,

An acid or a base

Base is usually preferred

23
Q

What does base catalysed hydrolysis of ester produce

A

Alcohol and the salt of the carboxylic acid (due to the alkaline conditions)

24
Q

What are the conditions for base catalysed hydrolysis of esters

A

Aqueous NaOH and under reflux

25
How to convert the salt formed from the base - catalysed hydrolysis of an ester back into a carboxylic acid
Neutralise with aqueous acid to convert the salt into the carboxylic acid Distil off the carboxylic acid
26
What are the conditions for acid catalysed hydrolysis of esters
Reflux the ester with aqueous HCl
27
What is the general form of an acyl chloride
RCOCl
28
How to name acyl chlorides
Add the ending -oyl chloride eg. CH₃COCl is ethanoyl chloride
29
What is added to a carboxylic to form an acyl chloride
thionyl chloride, SOCl₂
30
Advantages of using acyl chlorides instead of esterifying the carboxylic acid
The reaction occurs rapidly, without a catalyst and without heating Generally high yield Can be used to esterify phenols
31
How can acyl chlorides be converted into carboxylic acids
Reacting with water
32
How can acyl chlorides react with Aromatic compounds
Friedel-Crafts In the presence of a halogen carrier catalyst, the acyl group of an acyl chloride can substitute into an aromatic ring
33
What does acyl chloride + ammonia produce
Amides