How does Grignard work with Alkynes?

[dsony2284]

Does anyone know what a grignard CH3MgBr with an alkyne would do?

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[cuttiedentist]

Does anyone know what a grignard CH3MgBr with an alkyne would do?

grignard reagent remove any acidic H so it would do the same this as it does with other Hs.
i guess this is correct, sorry if im not

 

[dsony2284]

but theres no acidic H in an alkyne without an O, right? So what would happen here since there is no acidic hydrogen

 

[RING12]

but theres no acidic H in an alkyne without an O, right? So what would happen here since there is no acidic hydrogen

the H next to triple bond is acid too.

 

[drteeth]

The triple bond has a high electron density and slightly attracts the H's electrons. This makes the H slightly more acidic then say that of an alkane. The strongly basic Grignard would steel this H. So the CH3(-)MgBr would become CH4...

 

[quikag1]

Its another way to make an alkanide ion. Every1 else was correct in that it does pull off the acidic hydrgogen from the triple bond, but the main product of the rxn is the alkanide ion.

 

[shane.]

I think it is important to note that the alkyne must be terminal to have a H available for removal.

 

[Mstoothlady2012]

The triple bond has a high electron density and slightly attracts the H's electrons. This makes the H slightly more acidic then say that of an alkane. The strongly basic Grignard would steel this H. So the CH3(-)MgBr would become CH4...

thts right!

 

[BiomajorPreDent]

I resurrected this thread because I have a question relating to it.

If you react the grignard with the terminal alkyne and form the alkanide ion, you can then react it with any carbonyl group such as a ketone and it would act as a nucleophile and add like a normal grignard reagent right?

 

[loveoforganic]

Well it would react like a grignard, but it wouldn't be a grignard. You'd also obviously have an incompatibility with carboxylic acids.