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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: bioengineer123 on March 11, 2015, 12:21:10 AM

Title: two step grignard reaction
Post by: bioengineer123 on March 11, 2015, 12:21:10 AM
so in the following reaction im having a few problems.

ch3ch2ch2Och=o with brmgCh2ch(ch2)2 (isobutyl group with grignard reagent) and then brmg-ch3 in excess of water.

I think that the isobutyl will break the double bond of the oxygen and bond to the previously aldehyde carbon, and a water will drop off a hydrogen to become and alcohol. But im not sure what will happen in the second step, i thought that grignard reagents could react with alcohol but that doesnt seem to match up with the nmr data i was given for the product. any ideas here?
Title: Re: two step grignard reaction
Post by: Hunter2 on March 11, 2015, 02:05:17 AM
Your educt is not an aldehyde it is an ester n-propyl-formiate. This will transferred in the first step to an Acetal. This compose to propanole and 3-Methylbutanal. This can react again with Grignard and form 4-Methylhexan-2-on
Title: Re: two step grignard reaction
Post by: sjb on March 11, 2015, 03:22:27 AM
Quote from: bioengineer123 on March 11, 2015, 12:21:10 AM
so in the following reaction im having a few problems.

ch3ch2ch2Och=o with brmgCh2ch(ch2)2 (isobutyl group with grignard reagent) and then brmg-ch3 in excess of water.

I think that the isobutyl will break the double bond of the oxygen and bond to the previously aldehyde carbon, and a water will drop off a hydrogen to become and alcohol. But im not sure what will happen in the second step, i thought that grignard reagents could react with alcohol but that doesnt seem to match up with the nmr data i was given for the product. any ideas here?

If your first compound is CCCOC=O then this isn't an aldehyde, but an ester. With this in mind, does that help?