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1′-Acetoxychavicol acetate

Over christmas being a good Englishman, I kept to our traditions and ate turkey. I purchased a fine bird from a farm near where I live. The turkey was cooked to perfection in my oven, served up for christmas dinner before then we had the problem of what to do with the leftovers. Rather than allow the meat to go to waste we cooked up a series of curries with it.

We had an indian style curry

Then we had a Thai style curry, the flavour of the curry was very different so we choose to look at the label on the jar. We noticed a spice which we had not heard of before which is called “galangal”. It so happens that galangal contains a substance called 1′-acetoxychavicol acetate. When I looked up this compound in the chemical literature it looked to me as if it is formed in a similar way to  cinnamaldehyde which is formed from phenylalanine.

1'-Acetoxychavicol acetate, also known as galangal acetate

When I saw it, it was clear that the compound would be unstable when acid is present, it has an allylic alcohol which could form an allyl cation which would be further stabilised by the benzene ring. It is interesting that X. Yang, M. Rohr and J Jordan, Journal of Agricultural and Food Chemistry, 2009, 57(8), pages 3286-3290 comment that the hydrogenated compound has a similar flavour and is more stable in foods and drinks. Yang et. al. also explain how on boiling 1′-acetoxychavicol acetate for one hour in water they ended up with a mixture of three compounds, the three compounds confirmed my thoughts that a SN1 like reaction would occur which removes the acetate group from the allyl part of the molecule. Under the same conditions the hydrogenated compound was stable.

Normally I would draw you the mechanism, but as I am coming up to the part of the year when I teach organic chemistry I will let you work it out. Here is the reaction of galangal acetate with water to make a mixture of three compounds.

Reaction of galangal acetate with water to make a mixture of three products

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