ch26 Flashcards
What is the carbonyl functional group?
C=O
What is the reaction condition and reactants for oxidation of aldehydes?
In reflux
K2Cr2O7
H2SO4
Which reagent can distinguish between an aldehyde and a ketone?
Tollen’s reagent
Outline the detection of a carbonyl using Brady’s reagent
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
How does Tollen’s reagent distinguish between an aldehyde and a ketone?
Aldehyde group present
Silver mirror produced
Ketone group present
No silver mirror produced
How does Fehling’s reagent distinguish between an aldehyde and ketone?
Aldehyde group present
Brick red precipitate formed
Ketone group present
Stays blue/no change
Outline nucleophilic addition with a carbonyl and cyanide ion
Negative charge cyanide
Lone pair from C=O to O
Lone pair from -CN to C
O- lone pair to H on HCN
Lone pair in H-C to C in CN
OH formed
Nitrile formed
How can acidified potassium dichromate distinguish between aldehydes and ketones?
Aldehyde present
Orange solution to green
Ketone present
No change to solution
Why is potassium cyanide used instead of hydrogen cyanide?
It’s safer
Name the four carboxylic acid derivatives
Ester
Acyl chloride
Acid anhydride
Amide
What is the suffix for an acyl chloride?
-oyl chloride
What is the suffix for an acid anhydride?
-oic anhydride
When an acid anhydride reacts with a nucleophile, what are the two products?
R-CONu
R-COO-
ester and COOH
What is the characteristic mechanism to change an acyl chloride to a carboxylic acid?
Addition-Elimination
Describe esterification
Alcohol + carboxylic acid with conc sulfurated acid
Outline process of acid hydrolysis of an ester
Reverse of esterification
ester heated under reflux with dilute aqueous acid.
ester broken down by water with acid acting as catalyst.
products are carboxylic acid and alcohol
Outline process of alkaline hydrolysis of an ester
Irreversible.
Ester heated under reflux with aqueous hydroxide ions.
if aqueous sodium hydroxide is the alkali, salt sodium ethanoate is formed.
