organic 2 reactions info

tollens test for a aldehyde

• Tollens: silver nitrate dissolved in aqueous ammonia

• heated in a test tube with an aldehyde :

• colourless to silver mirror

Fehling’s solution or Benedict’s solution test for a ketone

• copper (II)ions dissolved in sodium hydroxide (blue solution)

• heated in a test tube with an aldehyde:

• the copper(II) ions are reduced to a brick-red precipitate of copper(I) oxide.

acidified dichromate ions reacting with an aldehyde

• Potassium dichromate(VI) with dilute sulfuric acid is often used.

• heat an aldehyde with acidified dichromate(VI) ions- you get a carboxylic acid.

• The dichromate(VI) ions are the oxidising agent, [O]

• orange to green solution

reagents for reducing aldehyde and ketone back to alcohols

• LiAlH4

• in dry ether