I am tasked by my textbook to synthesize 2-hexyne from 1-propanol. All carbon atoms must come from the starting material, 1-propanol.
My solutions manual (an older version) does not have this additional problem, so I am forced to ask here.
I understand that in this problem there is a double in carbon count in the product, so we are expected to somehow "fuse" the carbons from the starting material. I also understand that this means making an electrophilic carbon and a nucleophilic carbon from the starting materials. The electrophilic carbons that I know about are alkyl halides, alkyl tosylates, epoxides, and acid chlorides.
I'll choose to make an alkyl halide from the starting material through reaction of the primary alcohol (1-propanol) with thionyl bromide and pyridine as a base. Now I have my electrophilic carbon.
My nucleophilic carbon will be the acetylide anion. I could use a cyanide ion but that only gives me a one carbon increase. Plus that's not an allowed carbon source. So I dehydrate my primary alcohol (is this possible?) and creates 1-propene. I can brominate this in an inert solvent (i.e. methylene chloride). From here with the vicinal dihalide I can form the alkyne and then methyl acetylide. I can then react this with the alkyl halide I made previously.
How does this look?