Question

 how is an alkenyne named in a long unbranched hydrocarbon chain..???

Answer 1

The first step is to consider the number of carbon atoms forming a chain. If they are attached together in a linear (i.e. unbranched) configuration then the number of carbon atoms is indicated according to the same system as used for naming alkanes (see the examples listed in the table below).However, if the carbon atoms do not form a linear chain but includebranches, the longest linear chain of carbon atoms within the molecule determines the base of the name of the compound, onto which is added information about the branches incl. their lengths in terms of the number of carbon atoms in each branch (i.e. methyl- indicates a branch consisting of just one carbon atom attached to the main chain, ethyl- indicates a branch of two carbon atoms in length, etc.) and their positions along the longest linear carbon chain (e.g. attached to the 2nd carbon, 3rd carbon, etc.).