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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Nozon on August 13, 2019, 05:58:08 AM

Title: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: Nozon on August 13, 2019, 05:58:08 AM: I want to make 5-hydroxypentanoic acid from 4-bromo-1butanol

But what other reactant would be prefered?
I have an option to either use Grignard carboxylation or nitrile as my second reactant.

What would be best to use to make it?

My idea would be a nitril (NaCN) to remove the alkyl halide and then hydrolyse it acid (To avoid deprotonate my alcohol)
Would it work or am I just hopeless at organic chemistry?
Title: Re: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: chenbeier on August 13, 2019, 08:43:15 AM: Yes this would work. Also you can protect the hydroxylgroup and make grignard on the bromine side and react it with formaldehyde.
Title: Re: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: rolnor on August 13, 2019, 09:19:37 AM: You mean carbondioxide, not formaldehyde?
Title: Re: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: Nozon on August 13, 2019, 12:18:08 PM: Quote from: chenbeier on August 13, 2019, 08:43:15 AM
Yes this would work. Also you can protect the hydroxylgroup and make grignard on the bromine side and react it with formaldehyde.

How would i be able to protect my hydroxylgroup? Any suggestions on how? :) deprotonate it with a base?
Title: Re: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: chenbeier on August 13, 2019, 01:08:58 PM: Silyl, Ether, Ester,...
Title: Re: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: rolnor on August 13, 2019, 01:18:38 PM: If you deprotonate you can get ringclosure, a problem with the Grignard route is that you can get ringclosure of the final acid if you use a acid-labile protecting group. You could use a benzyloxymethyl group, this can be removed by hydrogenation and can be put on with mild base like triethylamine and benzyloxymethylchloride. The nitril-route is more convinient. I wonder why you want to do this, cant you buy the acid? Or hydrolyze the corresponding lactone?
Title: Re: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: rolnor on August 13, 2019, 02:12:18 PM: https://www.sigmaaldrich.com/catalog/search?term=Valerolactone&interface=All&N=0&mode=match%20partialmax&lang=en&region=SE&focus=product
Title: Re: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: AWK on August 13, 2019, 02:54:18 PM: Quote from: chenbeier on August 13, 2019, 01:08:58 PM
Silyl, Ether, Ester,...
Ester ???
Title: Re: What reactant to use to make 5-hydroxypentanoic acid from 4-brmo1-butanol
Post by: Nozon on August 13, 2019, 03:13:36 PM: Quote from: rolnor on August 13, 2019, 01:18:38 PM
If you deprotonate you can get ringclosure, a problem with the Grignard route is that you can get ringclosure of the final acid if you use a acid-labile protecting group. You could use a benzyloxymethyl group, this can be removed by hydrogenation and can be put on with mild base like triethylamine and benzyloxymethylchloride. The nitril-route is more convinient. I wonder why you want to do this, cant you buy the acid? Or hydrolyze the corresponding lactone?

It is for my organic exame and I've read my whole pensum, but there has been no introduction with any reaction alike. So I believe it's a question made in order to prove the students creativity and reason behind the final choice.

But thanks - made alot of sense. I'll keep that in mind.