Aldehydes, Ketones and Saccharides

Aldehydes, Ketones and Saccharides

Aldehydes – contains a carbonyl group at the end of the carbon chain. – RCOH

Ketones – contains a carbonyl group in the middle of the carbon chain. – RCOR

* 2,4-dinitrophenylhydrazine Test - Test for Carbonyl group * Sodium Bisulfate Test- Test for Aldehydes and Methy Ketones * White precipitate * Ketones with more than 2 carbon – non-reactive * Ketones with 2 carbons – slightly reactive

* Schiff’s Test – Test for aldehydes * Purple solution * Formalin - positive * Acetone (ketone) * Benzaldehyde – positive * Acetophenone (aromatic ketone)

* Tollen’s Test – Test for aliphatic and aromatic aldehydes * Silver mirror * Formalin – positive * Glucose – positive * Benzaldehyde – positive * Acetone

* Fehling’s Test – Test for Aliphatic aldehydes * Brick red precipitate (cuprous oxide) * Formalin – positive * Glucose – positive * Benzaldehyde * Acetone

* Sodium Nitroprusside Test – Test for presence of acetone * -Wine red solution

* Iodoform Test – Test for Methyl Ketones * Acetone – positive * Ethyl methyl ketone – positive * Ethyl acetate

* Special test for Benzaldehyde * Formation of crystals

* Molisch Test – General test for Carbohydrates * Violet ring (2nd layer) * Glucose – positive * Starch - positive * Benzaldehyde

* Bial’s Orcinol Test – Test for Carbohydrates * 5 carbon – blue to green * Ribose – green * 6 carbon – brown * Glucose – brown

* Phenylhydrazine Test – Test for reducing sugars * Osazone crystals * Glucose – positive

* Optical rotation – property of a substance that could rotate the plane of polarization of a beam of polarized