Chapter 26 - Carbonyls and Carboxylic Acids

Question 1

What is the carbonyl functional group?

Answer 1

C=O

Question 2

What is the reaction condition and reactants for oxidation of aldehydes?

Answer 2

In reflux
K2Cr2O7
H2SO4

Question 3

Outline the detection of a carbonyl using Brady’s reagent

Answer 3

Add 5cm depth of 2,4 DNPH (Brady’s reagent)
Use a pipette to add three drops of unknown
If no crystals form, add a few drops of sulphuric acid
A yellow/orange precipitate indicates carbonyl presence

Question 4

Which reagent can distinguish between an aldehyde and a ketone?

Answer 4

Tollen’s reagent

Question 5

How does Tollen’s reagent distinguish between an aldehyde and a ketone?

Answer 5

Aldehyde group present
Silver mirror produced
Ketone group present
No silver mirror produced

Question 6

Outline nucleophilic addition with a carbonyl and cyanide ion

Answer 6

Negative charge cyanide attacks the electron deficient carbon atom
Lone pair from -CN to C to form dative covalent bond

Lone pair from C=O to O by heterolytic bond fission
O- lone pair to H on HCN
Lone pair in H-C to C in CN
OH formed
Nitrile formed

Question 7

How can acidified potassium dichromate distinguish between aldehydes and ketones?

Answer 7

Aldehyde present
Orange solution to green
Ketone present
No change to solution

Question 8

Why is potassium cyanide used instead of hydrogen cyanide?

Answer 8

It’s safer

Question 9

Name the four carboxylic acid derivatives

Answer 9

Ester
Acyl chloride
Acid anhydride
Amide

Question 10

What is the suffix for an acyl chloride?

Answer 10

-oyl chloride

Question 11

What is the suffix for an acid anhydride?

Answer 11

-oic anhydride

Question 12

Describe esterification

Answer 12

Alcohol + carboxylic acid with conc sulfurated acid

Question 13

Outline process of acid hydrolysis of an ester

Answer 13

Ester heated under reflux with dilute aqueous acid

Ester broken down by water into carboxylic acid and alcohol

Question 14

Outline process of alkaline hydrolysis of an ester

Answer 14

Ester heated under reflux with aqueous hydroxide ions

Ester broken down by water into carboxylate ion and alcohol

Question 15

Describe the reaction of carbonyl compounds with NaBH4 and butanal

Answer 15

butanal + 2[H]&raquo_space;»> butan-1-ol

In the presence of NaBH4/H20

Question 16

reducing agent =

Answer 16

NaBH4

Question 17

Reaction of carbonyl compound with HCN and propanal

also state it’s purpose?

Answer 17

CH3CH2CHO + HCN&raquo_space;> CH3CH2CHOHCN

in the presence of H2SO4/NaCN

PURPOSE IS to increase the length of the carbon chain

Question 18

how is silver mirror formed

Answer 18

from the reduction of silver

Ag+ e-&raquo_space;> Ag(s)

Question 19

Distinguishing carboxylic acids from phenol

Answer 19

phenols are not acidic enough to reach with phenol with carbonates

but carboxylic acids are

Question 20

describe the preparation of acyl chlorides

Answer 20

Carboxylic acids + SOCl2&raquo_space;» acyl chloride + SO2(g) + HCL(g)

HCL is misty white fumy gas

Question 21

construct the acyl chloride flow chart

Answer 21

Add a pic next time

Question 22

acyl chloride&raquo_space;> primary amide

Answer 22

Acyl chloride + NH3&raquo_space;> primary amide +NH4Cl

R-COCl + 2NH3&raquo_space;» R-CONH2 + NH4Cl

Question 23

acyl chloride&raquo_space;> secondary amide

Answer 23

R-COCl + 2RNH2&raquo_space;» RCONHR + R+Cl-

Question 24

Reaction of acid anhydrides with alcohol

Draw out the reaction of

2(CH3CO)2O + C6H5OH

Answer 24

acid anhydride + alcohol&raquo_space;> Ester + carboxylic acid

2(CH3CO)2O + C6H5OH&raquo_space;> CH3COOC6H5 + CH3COOH

Question 25

Word equation between the reaction of acid anhydride reacting with alcohol

Answer 25

Acid anhydride + alcohol&raquo_space;> Ester + carboxylic acid