Sciencemadness Discussion Board

Cyclopropyl grignard

Xylitol - 4-9-2016 at 13:17

I want to synthesize the chemical: 2-cyclopropyl-2-butanol

I have never done a grignard reaction before, but I've done the research and it doesn't seem too difficult.

I need a little help though. To make this tertiary alcohol, would it be easier to react an acetate or ketone? Also should I make cyclopropyl grignard or should I use cyclopropyl ketone with ethyl grignard?

Is the cyclopropyl likely to open or harder to deal with than other simple grignards?

This next part might sound stupid:

How many moles do I need to react? I understand the mechanism of the reaction, but the generic info on grignards just says how many grams/mL they used in the reaction.

[Edited on 4-9-2016 by Xylitol]

Texium - 4-9-2016 at 13:44

Are we to assume that you have cyclopropanone or a cyclopropyl halide available? Neither of these compounds are very stable or readily available, and if synthesizing one of them is an unstated task here, you can forget about it.

If you do already have it though, yes, it will probably be very difficult to work with as the cyclopropane ring is quite unstable due to strain, and many reactions will lead to the ring opening.

As for that last part, if you can't figure that out on your own then you probably have no business trying to do Grignard reactions.

[Edited on 9-4-2016 by zts16]

Xylitol - 4-9-2016 at 14:25
Quote:

If you do already have it though, yes, it will probably be very difficult to work with as the cyclopropane ring is quite unstable due to strain, and many reactions will lead to the ring opening.


So would it be any better if the cyclopropyl ketone was used with ethyl grignard?

CuReUS - 4-9-2016 at 21:41

Quote: Originally posted by Xylitol  

So would it be any better if the cyclopropyl ketone was used with ethyl grignard?

yes
Quote: Originally posted by Xylitol  

How many moles do I need to react?

theoretically, 1 mole of ethylMgBr reacts with 1 mole of cyclopropyl methyl ketone to give the tertiary alcohol.But practically, you should use a slight excess of grignard so that all of the ketone reacts.
here is a reference - Chem.Abstr., 1948 , p. 1210

Xylitol - 5-9-2016 at 09:56

Thanks for the help. Is that reference specific to this reaction or is it just general info? I want to know because it doesn't seem like I can find it online.