alkynes

ethyne

explosive gas

used in oxyacetylene welding

but-1-yne

a terminal alkyne

but-2-yne

an internal alkyne

structure

a linear structure is adopted and it is sp hybridised

sp hybridisation

the s and one p orbital are hybridised to form 2 hybrids

energy is halfway between s and p orbitals

unsymmetrical dumbbell shape

angles of 180 degrees to each other

hydrogenation

a syn addition

a poisoned catalyst can be used to form alkenes selectively

alkylation

the H of a terminal alkyne can be removed using a very strong base

the lone pair of electrons on the C in the carbanion is in an sp hybrid orbital

only terminal alkynes are acidic

reaction with a haloalkane and

1. a new C-C bond is formed

2. stable halide ion is formed

3. Sn2 reaction