Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CH4 > Carboxylic Acids > Flashcards

Carboxylic Acids Flashcards

1
Q

Explain the high melting temperatures of carboxylic acids.

A

Boiling temperature increase with carbon chain length due to an increase in the number of Van der Waals. Boiling temperatures are unexpectedly high due to carboxylic acid molecules being able to hydrogen bond with each other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Explain the acidity of carboxylic acids.

A

Carboxylic acids produce hydrogen ions when dissolved in water and are thus considered as acids. These are able to act as strong acids because they can delocalise their negative charge over both oxygen atoms.
Carboxylic acids, along with phenols may be neutralised by sodium hydroxide to produce a salt.
Carboxylic acids are the only ones strong enough to liberate CO2 when hydrogen carbonate is added.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Test for carboxylic acids

A

Add to a solution of sodium hydrogen carbonate, effervescence indicates the presence of a carboxylic acid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Explain the solubility of carboxylic acids in water and other polar solvents.

A

Carboxylic acids can be soluble in water because they are able to hydrogen bond. The polar atoms of the hydroxyl group are attracted to the polar atoms of the water molecule.
Solubility decreases as the length of the carbon chain increases because the polar acid group is becoming a smaller part of the molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Formation of carboxylic acids by oxidation of 1° alcohols

Observation, R+C

A

> Acidified potassium dichromate(VI) or manganate(VII)
Refux
~ Colour change orange –> green or purple –> colourless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Production of aromatic carboxylic acids by oxidation of alkylbenzenes
(Observations, R+C)

A 
> Reflux
> Alkaline potassium manganate(VII)
~ Purple solution reduced to brown sludge (brown manganese(IV) oxide)
> Acidify with a dilute acid
~ White crystals produced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define decarboxylation

A

The loss of a carboxyl group (CO2), leads to a reduction in the carbon chain length.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Reduction of carboxylic acids using LiAlH4

Product, R+C

A

= 1° alcohol (reaction cannot be stopped to produce aldehyde)
> Non-aqueous solvent such as ethoxyethane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Decarboxylation of a carboxylic acid (or more usually its sodium salt)
(Product, R+C)

A

> Heat strongly
Solid sodium hydroxide or sodalime
= Alkane + Carbonate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is sodalime prepared?

A

Heat a mixture of sodium hydroxide and calcium oxide

Used as NaOH in equations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens when the calcium salt of the carboxylic acid is heated strongly?
(Reaction type and product)

A

*Decarboxylation

= Aldehyde/Ketone + Calcium carbonate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Carboxylic acid + PCl5 –>

A

Acyl Chloride + POCl3 + HCl (steamy fumes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

3Carboxylic acid + PCl3 –>

A

3Acyl chloride + H3PO3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Carboxylic acid + SOCl2 –>

A 
Acyl chloride(l) + SO2(g) + HCl(g)
Advantageous because two of the products are gases, therefore acyl chloride can be easily separated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How would you produce carboxylic acids from acyl chlorides?

By-product, R+C

A

= HCl (steamy fumes - fume cupboard)

> Water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Salt of carboxylic acid + Acyl chloride –>

Name one use of product

A

Acid anhydride + HCl

Use - production of cellulose based polymers

17
Q

What is observed when the ammonium salt of a carboxylic acid is reacted with FeCl3?

A

Reddish brown solution

18
Q

Producing an ester from a carboxylic acid

R+C

A

> Alcohol
Conc. sulphuric acid catalyst
Heat
Dry ether to prevent hydrolysis

19
Q

Hydrolysis of an ester using water or dilute acid

Product, R+C

A

= Alcohol + Carboxylic acid
> Dilute acid catalyst (if water is used)
> Reflux

20
Q

Hydrolysis of an ester using dilute alkali (sodium hydroxide)
(Product and advantage over hydrolysis with dilute alkali)

A

= Sodium salt of carboxylic acid + Alcohol

Advantage - Reaction is not reversible OR products are easier to separate

21
Q

Dehydration of carboxylic acids

Products, R+C

A

= Mixture of CO, CO2 and H2O
> Conc. sulphuric acid
> Warm

22
Q

How would you convert a carboxylic acid to an amide without using an ester or acyl chloride?
(Stages, R+C)

A 
1. Form ammonium salt of carboxylic acid
> Ammonium carbonate
> Excess carboxylic acid
2. Dehydration of ammonium salt
> Reflux
23
Q

Production of an amide from an acyl chloride

By-product, R+C

A

= HCl
> Ammonia
> Room temp.

24
Q

Production of an amide from an ester

By-product, R+C

A

= Alcohol

> Ammonia

25
Q

Formation of nitriles from halogenoalkanes

Mechanism, R+C

A

*Nucleophilic substitution
> KCN
> Ethanol solvent
> Reflux

26
Q

Reduction of nitriles

Product, R+C

A

= Primary Amine
> LiAlH4 dissolved in ethoxyethane
> Followed by treatment with dilute acid

27
Q

Acid hydrolysis of Nitriles

Product, R+C

A

= Carboxylic acid + NH4+
> Dilute acid
> Reflux

28
Q

Alkaline hydrolysis of nitriles using NaOH

Product, R+C

A

= Sodium salt of carboxylic acid + ammonia
> Reflux
> Dilute NaOH

CH4 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions