Soap by the Numbers

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Well-Known Member
Jun 28, 2014
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Kansas City, MO
I'm moving some thoughts from this thread to here where they may be more appropriate. n that thread I said:

While we are on the subject, how come we stop at the eight typical fatty acids? There's a group of even shorter chain fatty acids (C3-11)like caprylic, caproic, butyric; "intermediate" acids like Palmitoleic acid (16:1) .. just in case we want to make a macadamia oil soap for instance; then the longer chains (C20:1) like Gondoic acid. Why don't we count these?

Now I went searching and I found an interesting page which is the source of the following:

Fatty acids are predominantly unbranched and those with even numbers of carbon atoms between 12 and 22 carbons long react with glycerol to form lipids (fat-soluble components of living cells) in plants, animals, and microorganisms.

Is it safe to say that ONLY those acids which form lipids (even number of carbon atoms) are "saponifiable?" If so, it would explain my question about those "in between" (odd carbon numbers). It would also explain why capric (C10:0), caprylic (C8:0), caproic (C6:0), & butyric (C4:0) acids are the only short-chained saturated fatty acids mentioned.

It does seem like only lipids (those with even numbers which react with glycerol) would bring glycerin to play when they are saponified. I think that's a fair "rule?"

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