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A-Level Chemistry > Chapter 26.3- Carboxylic acids and their derivatives > Flashcards

Chapter 26.3- Carboxylic acids and their derivatives Flashcards

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1
Q

What is a carboxylic acid?

A

An organic molecule with the -COOH functional group, with a C=O carbonyl group and -OH acid group.

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2
Q

How are carboxylic acids produced?

A

Oxidation of primary alcohols under reflux (alcohol to aldehyde to carboxylic acid)

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3
Q

How do carboxylic acids dissociate?

A

Carboxylic acids are weak acids so they slightly dissociate when in solution, forming an H+ ion and carboxylate ion RCOO-

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4
Q

How do carboxylic acids react with carbonates?

A

They react as acids producing a carboxylate salt, water and CO2

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5
Q

What is the chemical test for a carboxylic acid?

A

React with a carbonate NaHCO3 and observe for fizzing or bubble through limewater

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6
Q

How soluble are carboxylic acids?

A

Small chain carboxylic acids form H- bonds with water molecules due to lone pair on O from water and δ+ H in -OH group, making them soluble in water.
Longer chain carboxylic acids are less soluble

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7
Q

What is the esterification reaction?

A

Carboxylic acids react with alcohols with a strong acid catalyst to produce an ester and water.
RCOOH + ROH –> RCOOR’ + H2O (with strong acid catalyst)

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8
Q

What is easy to remember in the esterification reaction?

A

-OH group from carboxylic acid and H from alcohol group are removed and form water, the R groups remaining join together

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9
Q

What are the conditions for the esterification reaction?

A

Strong acid catalyst and heat

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10
Q

How do you name esters?

A

Start with alkyl group ending with -yl, then other part with COO ending with -oate.
Carbon atoms either side of central O are number 1

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11
Q

What are some properties of short chain esters?

A

Volatile, sweet smelling, good solvents for polar molecules

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12
Q

What are esters?

A

Organic molecules with an -COO- group

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12
Q

What are some uses of esters?

A

Perfumes, food flavourings, solvents, plasticisers

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13
Q

What are animal fats and vegetable oils?

A

Esters of naturally occurring glycerol (propane- 1,2,3- triol), they are tri (glyceride) esters

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14
Q

What happens when glycerol undergoes esterification?

A

It forms triglyceride esters

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15
Q

What happens when carboxylic acids dissociate?

A

They lose the H from the -OH group and the negative charge is shared over the carboxylate group, making the ion more stable

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16
Q

What is ester hydrolysis?

A

The reverse reaction to esterification, converting esters back into carboxylic acids and alcohols. Water is added and depending on conditions different products are formed

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17
Q

What happens in acid hydrolysis?

A

Ester reacts with water to produce carboxylic acid and alcohol (with acid catalyst)

18
Q

What are some features of acid hydrolysis?

A

Reversible, low yield, slow, acid catalyst at RT

19
Q

What happens in alkaline hydrolysis?

A

Ester reacts with water then further with base, eg NaOH to produce a carboxylate salt, eg RCOONa and an alcohol

20
Q

What is saponification?

A

Producing the carboxylate salt in alkaline hydrolysis

21
Q

What are carboxylate salts commonly used for?

A

Soap and detergents

22
Q

Why are carboxylate salts used in soaps?

A

They have an ionic, polar head making it hydrophilic and a non-polar, hydrophobic tail. The tail will mix with grease and the head mixes with water, allowing the two to mix

23
Q

What happens when animal fats or vegetable oils are boiled with NaOH?

A

Saponification reaction in which glycerol from triglyceride esters and sodium salts are produced

24
Q

What is transesterification and what is an example reaction?

A

The conversion of one ester into another, eg in the production of biodiesel

25
Q

How is biodiesel produced?

A

By reacting vegetable oils with methanol with a strong acid catalyst to produce a mixture of methyl esters and glycerol

26
Q

What is biodiesel?

A

A mixture of methyl esters of long chain carboxylic acids

27
Q

What is an acid anhydride?

A

An organic molecule formed with water removed from two carboxylic acids

28
Q

How do acid anhydrides react?

A

Undergo the same reactions as carboxylic acids but do not require a catalyst, only heat, as they are more reactive

29
Q

What are acid/ acyl chlorides?

A

Organic molecules with the -COCl group

30
Q

What are primary amides?

A

Organic molecules with the -CONH2 group

31
Q

What are N-substituted amides?

A

Amides in which a H from the NH2 group is replaced by something else, eg methyl, phenyl, etc.

32
Q

How do acyl chlorides react?

A

They are very reactive and require no catalyst or heat, however they produce toxic HCl and are expensive

33
Q

What mechanism and conditions do the derivatives react via?

A

Nucleophilic addition-elimination, under aqueous conditions

34
Q

What is produced from an acyl chloride and and water?

A

Carboxylic acid and HCl

35
Q

What is produced from an acyl chloride and alcohol?

A

Ester and HCl

36
Q

What is produced from an acyl chloride and ammonia?

A

Amide and HCl

37
Q

What is produced from an acid anhydride and water?

A

Two carboxylic acids

38
Q

What is produced from an acid anhydride and alcohol?

A

Ester and carboxylic acid

39
Q

What is produced from an acid anhydride and ammonia?

A

Amide and carboxylic acid

40
Q

What is produced from an acid anhydride and primary amine?

A

N-substituted amide and carboxylic acid

41
Q

What is the outline for nucleophilic addition-elimination?

A

Lone pair of nucleophile moves to C in carbonyl group
Atom with lone pair bonds and now has positive charge
Electrons from bond between H and positive charge move to atom, releasing H+
Electrons from pi bond move back to C in carbonyl group
Electrons from bond between C and remaining group move to the remaining group

42
Q

What is the reaction for aspirin?

A

Salicylic acid (carboxylic) reacts with ethanoic anhydride (acting as alcohol) to production aspirin (ester) and ethanoic acid (carboxylic)

A-Level Chemistry (24 decks)

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