Sciencemadness Discussion Board

Valeric Acid Preparation Ideas

ThunderSkunk - 21-7-2012 at 21:51

I am looking to find a way to extract or conveniently produce Valeric acid [pentanoic acid]. I was hoping someone out there knows of a neat way to do this.

The end goal is to synthesize methyl valerate [a fairly common fruity aroma added to foods and detergents] by means of Fischer Esterification.

I was just hoping to pick people's brains. I figured since that the stuff is produced naturally by the plant Valeriana officinalis, that there might be some published paper out there which detailed a synthesis or fermentation to exploit. My Google keywords can back empty though... :(

Thank you in advance!

P.S.

I am aware of the oxo process which uses carbon monoxide and butylene to form a "Valeraldehyde" intermediate... I just think smelling good is slightly less important than my ability to breathe. ;)

chemrox - 21-7-2012 at 22:23

I would encourage you to do your own research. Butyl bromide + Mg + CO2 --> pentanoic acid should work. Please look up preparation and reactions of Grignard reagents.

ThunderSkunk - 21-7-2012 at 23:55

Wow, that was fast! Sorry for being lazy and ignorant. You have a nice evening.

Endimion17 - 22-7-2012 at 00:31

Wrong place to search for such ideas. This is Reagents and Apparatus Acquisition, you need Organic Chemistry.

kavu - 22-7-2012 at 01:27

In case you don't want to bother with a grignard reaction straight forward oxidation of n-pentanol works too. Refluxing with KMnO4 in basic aqueous solution should work like a charm.

Dr.Bob - 23-7-2012 at 13:16

Warning, while the esters of valeric acid may be lovely to smell (I remember amyl acetate being the small of bananas), the acid itself is not very pleasant and smells of body odor. It is far better than butanoic acid (which smells like bad foot odor and underarm pit all mixed with some fungal infection), but will still leave you smelling like someone who hasn't bathed in days. But the Grignard will work well with CO2. I think even just going to hexanoic acid makes the acid's smell much better, but not sure what those esters small like.

Ozone - 23-7-2012 at 16:19

You could also extract it from valerian: http://en.wikipedia.org/wiki/Valerian_(herb)

O3

bahamuth - 24-7-2012 at 06:59

Quote: Originally posted by Dr.Bob  
Warning, while the esters of valeric acid may be lovely to smell (I remember amyl acetate being the small of bananas), the acid itself is not very pleasant and smells of body odor. It is far better than butanoic acid (which smells like bad foot odor and underarm pit all mixed with some fungal infection), but will still leave you smelling like someone who hasn't bathed in days. But the Grignard will work well with CO2. I think even just going to hexanoic acid makes the acid's smell much better, but not sure what those esters small like.


Amyl acetate is not made with valeric acid, and valeric acid smells more like fatty acetic acid than body odor. Additionally hexanoic acid smells like horny male goat... Larger carboxylic acid chains give a more "fatty" smell.

I'd do the oxidation of n-pentanol, you could even do the oxidation and methylation in one step with trichloroisocyanuric acid.

The Oxidation of Primary Alcohols to Methyl Esters and Diols to Lactones Using Trichloroisocyanuric Acid -SYNTHETIC COMMUNICATIONS? Vol. 33, No. 12, pp. 2003–2009, 2003

Doc B - 30-7-2012 at 03:12

Hydrolysis of N-butylcyanide will afford n-valeric acid (b.p 186degC)

N or iso- valeric acid can also be prepaired from the oxidation of N or iso-amyl alcohol respectively. KMnO4, dil. H2SO4 ate two common reagents suitable for the task.