It takes alkynes to make a world

Nomenclature: CnHn


All the alkynes are linear e.g.

It has one s bond and two p bonds orthogonal to one another in the triple bond. See diagram above.

Physical properties:

Mpt's and Bpt's are a little higher than the corresponding alkanes and alkenes.

Name each compound by the IUPAC system:


Chemical properties:

1. Additions: These are similar to alkenes; electrophilic or free radical. The intermediate double bond compound can usually be isolated.

Prop-1-yne will add to:

a) Hydrogen Bromide

b) Bromine

The bromine adds in a similar way to the alkene but because of the steric hindrance the second bromine adds trans to the first bromine.

c) Lindlar catalyst

d) Hydrogen

2. 1-Alkynes as acid

We can see from the results table that ethyne is less acidic than ethanol. The hydrogen can be removed by Sodium azanide (NaNH2) in liquid ammonia.

Also, with the use of a grignard reagent;

Preparation of alkynes :

1. Eliminations. The elimination of bromine.

2 Carbide hydrolysis.