Aldehydes AND KETONES

Aldehydes Structure and General Formula

R-CHO (Carbonyl group at the chain end)

(Common and IUPAC)

Common: Formaldehyde | IUPAC: Methanal (HCHO).

(Common and IUPAC)

Common: Acetaldehyde | IUPAC: Ethanal (CH3CHO).

Method of Preparation of Aldehydes

Oxidation of primary alcohol and hydration of alkynes

How to prohibit primary alcohol not to become carboxylic acid and

To form aldehyde

Must be distilled off immediately to prevent further oxidation into acid.

Oxidation of alcohol to obtain aldehyde

Use primary alcohol+ nasent oxygen with oxidising agent

(K2 CR2 07 ,H+) and get aldehyde+

Oxidation of Aldehydes

Easily oxidized to carboxylic acids using K2Cr2O7 or KMnO4.

Reduction of Aldehydes

Reduced to primary alcohols using LiAlH4 in dry ether. with dil H2SO4

Addition of HCN to Aldehydes

Form hydroxypropanenitrate from ethanal

Form 2-hydroxy-2-methylpropanenitrate

aldehydes and Uses of Formalin

A 40% aqueous solution of methanal used as a disinfectant and preservative.

Chemical test for Aldehydes

Strong reducing agents

Nomenclature of aldehyde

Common name base on carboxylic acid

Indicated by Greek letter

IUPAC Name: name of parent hydrocarbon carbon

the suffix al instead of e

Use of Cinnamic aldehyde

Perfume of natural sweet or fruity scents

Aldehydes are___compound

versatile compound

Hydration of alkane to obtain aldehyde

Use ethyne and water with dil H2 SO4 at 60’C and Hg S O4 to obtain ethanol

Ketone Structure and General Formula

R-CO-R' (Carbonyl group in the middle)

(Common and IUPAC)

Common: Acetone | IUPAC: Propanone (CH3COCH3).

Preparation of Ketones

1. Oxidation of secondary alcohols by using acidified K2Cr2O7.

2. Hydration of alkane by using dil H2 SO4 at 60’C and Hg S O4 or H2 S O4.

Ketone Oxidation

Do not oxidize easily but under vigorous condition

Reduction of Ketones

Reduced to secondary alcohols using LiAlH4 in dry ether.

Nomenclature of kentones

Common name: two alkyl +kentones but the first member is acetone

IUPAC name: derived from hydrocarbon like alkane but change to alkanone

Properties of kentones (state)

At room temperature,methanal is gas and ethanal is a volatile liquid.

Solubility of aldehyde and kentones

Methanal , ethanal and propanone are water soluble.

Use of Aldehyde

Versatile compound that can help make resins,dyes, organic compound.

40% of aqueous solution of methanal

Formalin

Formalin is used for

a desinfectant and a preservatives for biological specimen

Where kentones are used as popular solvents.

In making moderately polar substance, including waxes, paints, lacqures, varnishes, glues

The simple kentones (propane) acetone is used for?

an effective solvents in many nail polish removers, plastic cements, resins, and varni