Write the structure and IUPAC name of the following compounds:
(i) Metylacetylene
(ii) Ethylacetylene
(iii) Dimethylacetylene
(iv) Isopropylmethylacetylene
Strategy: Alkynes are named like the alkenes except for the following two points:
(1). The suffix-yne is added to the characteristic root.
(2). Because the linerar arrangement about the triple bond does not lead to geometric isomerism. the prefixes cis-and itrans-are not used.

Explanation

(i) `CH_3--=CH`, propyne
(ii) `CH_3CH_2-C-=CH`, but-1-yne
(iii) `CH_3-C-=C-CH_3` but-2-yne
(iv). `overset(5)(C)H_(3)-underset(CH_(3))underset(|)overset(4)(C)H-overset(3)(C)-=overset(1)(C)H_(3),` 4-emthylpent-2-yne