questions on lipids and saponification number

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adlsia
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Post by adlsia » Sun Nov 04, 2007 12:48 pm

hi there..

i have a problem about lipid..
1) what is the relationship between saponification number and number of carbon atoms in fatty acids chain?

2) and how the saponification number gives effect on soap production?

i hope anyone whom knows about this may help me solve this problem..

Thank you for those whom contribute..

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Draco
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Post by Draco » Mon Nov 05, 2007 1:02 pm

1) well I think this has something to do with the number of bonds between the carbon atoms. If there are only double bonds then the fatty acid chain is saturated. If there are double bonds then the fatty acid chain is unsaturated.
Why can't this be left blank?

blcr11
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Post by blcr11 » Mon Nov 05, 2007 5:40 pm

I think you’re confusing the iodine number with the saponification number, Draco. The iodine number is a measure of the degree of unsaturation. Molecular iodine decolorizes as it adds across a double bond, making a di-iodo compound at every reactive double bond in the molecule(s). The greater the degree of unsaturation, the more iodine will be consumed, until finally there are no longer any reactive bonds left and futher additions of iodine no longer decolorize—that’s the endpoint of the titration, acutally—the point at which the purple color of iodine just persists. The saponification number of an oil or fat is the amount of sodium hydroxide it takes to fully release the acids and form their respective sodium salts (that is, soap) from 1 mg of fat or oil. The lower the number, in general, the higher the average molecular weight of acids esterified to glycerol, and the less soluble are the respective soaps. You can do the same thing using potassium hydroxide and you will get a slightly different set of numbers for the same set of compounds, but the trends should be similar.

adlsia
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Post by adlsia » Wed Nov 07, 2007 6:36 pm

Thanks to Draco and blcr11

both of your info help me a lot:-)

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