What kind of structural information about organic compounds can be deduced from the following information?
(i) A hydrocarbon which rapidly decolourises bromine?
This compound is an alkene.
(i) A hydrocarbon which rapidly decolourises bromine?
This compound is an alkene.
Reasoning: Alkenes undergo an ionic addition reaction with bromine/chlorine in the presence of tetrachloroethane or acetic acid, at room temperature in the absence of light. In the presence of light free radical addition reaction with the halogens will occur.
(ii) A compound that is oxidised to a ketone.
This is a secondary alcohol
Reasoning: Secondary alcohols are oxidised to ketones. The reaction involves the fusion of the RO-H bond and the formation of a carbocation which is stabilised by electron donating alkyl groups.
(iii) A compound which reacts with iodine in alkaline solution to form a yellow solid
The compound contains either a CH3CH(OH)- or a CH3CO- group.
Reasoning: Both undergo the iodoform reaction. Triiodomethane and a carboxylic acid are produced at the end of the reaction.The methyl group is is converted triiodomethane, which is a yellow precipitate.
(iv) A compound which forms a silver mirror when heated with Tollens' reagent.
An aldehyde will form this silver mirror.
Reasoning: Tollens reagent is used to distinguish between aldehydes and ketones. With Tollens reagent Ag+ ions react with OH- of aqueous ammonia to produce a brown precipitate of AgOH which is dissolved on addition of an excess of aqueous ammonia under the formation of
[Ag(NH3)2]+. This is reduced to metallic silver by aldehydes as it has hydrogens on the carbonyl carbon which can be removed while the ketone does not and so it cannot undergo this oxidation.
(v) A organic compound reacts with sodium carbonate
(iii) A compound which reacts with iodine in alkaline solution to form a yellow solid
The compound contains either a CH3CH(OH)- or a CH3CO- group.
Reasoning: Both undergo the iodoform reaction. Triiodomethane and a carboxylic acid are produced at the end of the reaction.The methyl group is is converted triiodomethane, which is a yellow precipitate.
(iv) A compound which forms a silver mirror when heated with Tollens' reagent.
An aldehyde will form this silver mirror.
Reasoning: Tollens reagent is used to distinguish between aldehydes and ketones. With Tollens reagent Ag+ ions react with OH- of aqueous ammonia to produce a brown precipitate of AgOH which is dissolved on addition of an excess of aqueous ammonia under the formation of
[Ag(NH3)2]+. This is reduced to metallic silver by aldehydes as it has hydrogens on the carbonyl carbon which can be removed while the ketone does not and so it cannot undergo this oxidation.
(v) A organic compound reacts with sodium carbonate
The organic compund contains a carboxylic acid group or a derivative of such a group.
Sodium carbonate is basic and reacts with carboxylic acid to produce a salt, carbon dioxide and water as products. The effervecence is therefore, due to the presence of carbon dioxide. Carboxylic acid derivatives react in a similar manner.
Name the functional groups present in the following compound:
1.Carboxylic acid (COOH)
2. Phenol (C6H5OH)
What is the molecular formula for the above compound?
C7H6O3
