Chemistry [[Module Three]] Alcohols: Classifying and Reactions

- alcohols classified as primary, secondary or tertiary

- depends on which the carbon the OH group is attatched to

- Many reactions are the same, regardless of where the OH group is

- but three types of alchol differ when oxidised.

[[Oxidation of Alchol]]

- acidified potassium dichromate

- colour change from Orange to Green as Dichromate ions are reduced - test to distinguish primary and secondary from tertiary alcohols.

[Primary Alcohol]

- oxidised to Aldehydes

- colour change from orange to green

- Aldehyde still has H atom and so can be oxidised further

- Further oxidised to Carboxylic Acid

- To stop this happening, remove the aldehyde as it is produced using a condensor

- To get Carboxylic acid, prevent the product from escaping and heat under reflux

[Secondary Alcohol]

- oxidised to Ketones

- No further oxidation

- colour change from orange to green

[Tertiary Alcohols]

- no oxidation

- no colour change

[[Distinguishing bewteen Aldehydes and Ketones]]

- test for secondary/primary alchols

- use of mild oxidising agent

[[Fehlings Solution]]

- colour change from Blue to red in the presence of Aldehydes

- Not oxidised by Ketones

- Copper (II) Complex reduced to Copper (I)

[[Tollens Reagent]]

- Silver Mirror formed when warmed in the presence of Aldehydes

- Not oxidised by Ketones

- [Ag (NH302]+ reduced to Ag