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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: whyohme on August 24, 2012, 08:06:17 PM

Title: how to prepare these products
Post by: whyohme on August 24, 2012, 08:06:17 PM
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2F24.media.tumblr.com%2Ftumblr_m9aav7PMfS1rdw744o1_500.jpg&hash=6689e3a4f1f17f76c4610f3a766a81b65834381a)

how to get butanoic acid and hexanoic acid at the same time from 1-bromopentane?

Thanks!
Title: Re: how to prepare these products
Post by: discodermolide on August 24, 2012, 08:16:55 PM
Quote from: whyohme on August 24, 2012, 08:06:17 PM
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how to get butanoic acid and hexanoic acid at the same time from 1-bromopentane?

Thanks!

Hexanoic acid is easy, butanoic acid need a bit more thought.
Have you any ideas?
Title: Re: how to prepare these products
Post by: whyohme on August 24, 2012, 10:25:49 PM
Quote from: discodermolide on August 24, 2012, 08:16:55 PM
Quote from: whyohme on August 24, 2012, 08:06:17 PM
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2F24.media.tumblr.com%2Ftumblr_m9aav7PMfS1rdw744o1_500.jpg&hash=6689e3a4f1f17f76c4610f3a766a81b65834381a)

how to get butanoic acid and hexanoic acid at the same time from 1-bromopentane?

Thanks!

Hexanoic acid is easy, butanoic acid need a bit more thought.
Have you any ideas?

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2F24.media.tumblr.com%2Ftumblr_m9ahcuICPA1rdw744o1_500.jpg&hash=922e5e9f5ce535b7fe408546585d0ea4e1fc8c67)

I came up with this. I have no idea how to obtain hexanoic acid. I dont find any example shows "more-carboned product" example. please help. thanks
Title: Re: how to prepare these products
Post by: discodermolide on August 25, 2012, 12:08:46 AM
That's OK for the first one.
The second one is you make a Grignard reagent with magnesium then treat it with CO2. There the chain goes from 5 carbons to 6!
Title: Re: how to prepare these products
Post by: orgopete on August 25, 2012, 12:08:51 AM
You might want to check the reagents for the elimination so you don't get substitution, but otherwise fine.

Hexanoic acid hint, if bromopentane is made into a nucleophile, then what electrophile will give the acid upon workup?
A second option is if bromopentane is the electrophile, what one carbon nucleophile will give the same oxidation state as a carboxylic acid (it will give a carboxylic acid after hydrolysis)?
Title: Re: how to prepare these products
Post by: whyohme on August 25, 2012, 12:57:28 AM
Quote from: discodermolide on August 25, 2012, 12:08:46 AM
That's OK for the first one.
The second one is you make a Grignard reagent with magnesium then treat it with CO2. There the chain goes from 5 carbons to 6!


thank you
Title: Re: how to prepare these products
Post by: whyohme on August 25, 2012, 01:09:49 AM
Quote from: orgopete on August 25, 2012, 12:08:51 AM
You might want to check the reagents for the elimination so you don't get substitution, but otherwise fine.

Hexanoic acid hint, if bromopentane is made into a nucleophile, then what electrophile will give the acid upon workup?
A second option is if bromopentane is the electrophile, what one carbon nucleophile will give the same oxidation state as a carboxylic acid (it will give a carboxylic acid after hydrolysis)?

if bromopentane is electrophile, CO2 will be the nucleophile ?   
Title: Re: how to prepare these products
Post by: orgopete on August 25, 2012, 11:29:47 AM
No CO2 is an electrophile. The carbon will accept electrons, for example from a Grignard reagent. You need the carbon to possess electrons than can be donated. Hint, it is a one carbon nucleophile with a nitrogen attached.