Carbonyls, carboxylic acids and esters. Flashcards
Aldehyde classification.
Carbonyl functional group found at the end of the carbin chain
Carbon atom of carbonyl group is attached to 1 or 2 H atoms
CHO.
Carbonyl functional group.
C=O.
Ketones classification.
Carbonyl functional group is attached to 2 carbon atoms in the carbon chain
CO.
Rules for naming carbonyl compounds.
Add a suffix to the stem of the longest carbon chain
-al for an aldehyde
-one for a ketone
In an aldehyde the carbon atom of the carbonyl group is always carbon 1
In a ketone the carbonyl carbon atom needs to be numbered.
Oxidation of aldehydes.
Oxidised to carboxylic acids
When refluxed with dichromate(VI) ions, Cr2O7(2-)/H+.
Oxidiation of ketones.
Do not undergo oxidation reactions
Can help distinguish between these.
Why is carbonyl reactivity different to alkene reactivity?
C=C bond in alkenes is non-polar
C=O bond in carbonyls is polar.
Why is the C=O bond polar?
O is more electronegative than C
e- density in the bond lies closer to O than the C atom
C end is slightly positive and O end slightly negative.
What does a nucleophile do?
Is attracted to and attacks the C + atom resulting in addition across the double bond
Nucleophilic addition.
Reducing an aldehyde.
NaBH4 is used as a reducing agent
Reduced to a primary alcohol.
Reducing a ketone.
Reduced to secondary alcohols
By NaBH4.
Explanation for the mechanism for the reaction w/ NaBH4.
Explanation for the mechanism for the reaction w/ NaCN/H+.
How to detect the presence of a carbonyl group.
2,4-DNP/brady’s reagant
In the presence of a carbonyl group, a yellow or orange precipitate is formed.
Distinguishing between aldehydes and ketones.
A fresh sample of the compound can be classified using Tollen’s reagant-solution of silver nitrate in aq ammonia
Aldehyde group=silver mirror produced
Acts as an oxidising agent
Silver ions are reduced to silver
Aldehyde oxidised to carboxylic acid.
What is a carboxylic acid?
An organic acid that contains the carboxyl group
-COOH.
Naming carboxylic acids.
Add suffix -oic acid to the stem of the longest carbon chain
Carboxyl carbon atom is always carbon number 1.
Solubility of carboxylic acids.
Carboxylic acid derivitives.
Esters
Acyl chlorides
Acid anhydrides
Amides.
