AC10: Carboxylic acids & their derivatives Flashcards

1
Q

what do carboxylic acids become when they donate a proton

A

carboxylate ion
RCOO- + H+

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2
Q

What is formed when you react a carboxylic acid with a base, for example, ethanoic acid + sodium hydroxide

A

sodium ethanoate and water

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3
Q

Describe and explain the melting/boiling points of carboxylic acids

A

relatively high compared to alkanes of similar size, due to hydrogen bonding between its molecules, that are stronger than London forces and pd-d forces

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4
Q

What is formed when reacting propanedioic acid with ammonia

A

ammonium propanedioate

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5
Q

Compare the mpt/bpt of salts of carboxylic acids to their original acids

A

higher mpt than original acid due to more energy needed to break many strong ionic bonds, which are stronger than H-bonding between the carboxylic acid molecules

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6
Q

Describe and explain the solubility of carboxylic acids in water

A

generally soluble in water due to their ability to form H-bonding with H2O

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7
Q

What reagents and conditions are required to esterify a carboxylic acid

A

react carboxylic acid with alcohol, heat under reflux, concentrated sulfuric acid

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8
Q

What is produced in an esterification reaction of a carboxylic acid

A

ester and water

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9
Q

What is produced when reacting propanoic acid with ethanol, heat under reflux and concentrated sulfuric acid

A

ethyl propanoate and water

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10
Q

What is the functional group of an ester

A

COO

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11
Q

what happens to the carboxylic acid and alcohol in an esterification reaction

A

-H atom is removed from -OH group in carboxylic acid, and -OH removed from alcohol (or vice versa) to form H2O and ester

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12
Q

What is an acid anhydride and how is it formed

A

two carboxylic acids undergo a condensation reaction - removal of water, two acyl groups are bonded to the same oxygen atom forming an acid anhydride

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13
Q

What is formed when you react an acid anhydride with an alcohol

A

ester and carboxylic acid

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14
Q

What are the benefits of using acid anhydrides over carboxylic acids for making esters

A

The acid is not reversible therefore higher yield of ester
no concentrated sulfuric acid catalyst is needed and so a cheaper process
can be done at RTP, reduces cost, and no cost to separate homogenous catalyst

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15
Q

state the reagents and conditions when esterifying an acid anhydride

A

alcohol
RTP
no catalyst

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16
Q

state the reagents and conditions when doing an acid catalysed hydrolysis of esters, and state what the products are

A

water, heat under reflux with aqueous HCl

forms carboxylic acid and alcohol

17
Q

What is an issue of acid catalysed hydrolysis of esters

A

relatively low yield due to the reactio nbeing reversible

18
Q

state the reagents and conditions when doing an alkali/base catalysed hydrolysis of esters, and state what the products are

A

OH-
heat under reflux with aqueous NaOH
forms base carboxylate and alcohol

19
Q

state the products of methyl propanoate + NaOH with heat under reflux and aqueous NaOH

A

Sodium propanoate and methanol

20
Q

Why is alkali/base catalysed hydrolysis of esters better than acid catalysed hydrolysis of esters

A

higher yield than acid hydrolysis, as the reaction is irreversible

21
Q

how can you convert the carboxylate to a carboxylic acid

A

by adding excess inorganic acid to neutralise the mixture then distill off the carboxylic acid

22
Q

What is an acyl chloride

A

carboxylic acid but the -OH is replaced with a -Cl

23
Q

Give three uses of acyl chlorides in organic synthesis reactions

A

1- acylation
2- esterification
3- forming carboxylic acids

24
Q

How can an acyl chloride by used for an acylation reaction, state any reagents and conditions

A

acyl chloride plus organic compound, AlCl3
forms acyl organic compound and HCl

25
Q

How can an acyl chloride by used for an esterificatoin reaction, state any reagents and conditions

A

acyl chloride plus alcohol
forms ester and HCl
no catalyst, at RTP

26
Q

How can an acyl chloride by used for forming carboxylic acids, state any reagents and conditions, what type of reaction is this

A

acyl chloride plus water forms carboxylic acid and HCl (hydrolysis reaction)

27
Q

what compound do acyl chlorides react well with and what does it form

A

phenols -> phenolic esters

28
Q

how do you prepare acyl chlorides

A

carboxylic acids + thionyl chloride (SOCl2) -> acyl chloride + SO2 + HCl