[orgo814]

I am having trouble with the synthesis of 4, 4-dimethyl-2-pentyne. I am told to start with CH3C≡CH.
The synthesis starts out with Step 1: CH3C≡CH + Na NH2(-)  ---> CH3C≡:(-) + NH3   - charge is indicated in parentheses

                                      CH3                                        CH3
                                         /                                            /
Step 2: CH3C≡:(-) + CH3- C - Br --->  CH3≡CH +    CH2=C        + Br(-)
                                       /                                             /
                                 CH3                                          CH3

Now, I'm confused. This is the way my professor said it starts when I asked him. But how do I get from here to 4, 4-dimethyl-2-pentyne? It can't go by substitution obviously, it has to go by elimination which is why the hydrogen was taken off of the one carbon in the tert-butyl group forming that double bond.

Please be clear in your answer and please do not respond in question form because that does not help, sorry.

[fledarmus]

Why did you start by pulling a proton? It seems like your professor is just pointing out that when you put a strong base with t-butyl bromide you get elimination instead of substitution.

Have you looked at copper acetylide chemistry?

Sorry for asking questions, but if you read the forum rules http://www.chemicalforums.com/index.php?topic=33740.0, you'll see that this is the way we teach on this forum.

[orgo814]

That's just the way he told me to do it. I have no idea how to progress from that step though to the formation of the product im being asked to get.

[fledarmus]

The professor told you that the first two steps that you have written are the first two steps in the correct reaction sequence?

[orgopete]

What carbon-carbon bond forming reactions have been discussed in class? I am presuming the problem is supposed to use one of those. It could also be an error. That happens sometimes.