[dubz]

hi guys!  i'm quite confused.. how do you draw 2,5-dimethylbut-3-yne?  butyne means there are 4 carbons in the alkyne but how come there is a 5 substituent..can anyone draw or illustrate it for me?  thanks in advance.

[discodermolide]

So where did this name come from?
Have you attempted to draw it?

[dubz]

well, it came from a practice set i'm answering..here's the question: 
"4.   Show the structure of the enol intermediate you would expect in the reaction of 2,5-dimethylbut-3-yne with mercury(I) sulfate dissolved in aqueous sulfuric acid."

i haven't tried drawing it because the 5 substituent on the name confuses me..

[discodermolide]

This must be an error, a but-3-yne has the following structure:

and is actually a but-1-yne!

[dubz]

yeah, that's another point..that's why i got really confused..oh well, i guess just skip it then.. thanks for the help man, you're always reliable