In a Nutshell:
While vegetable oils have the advantage of being biodegradable, vegetable oils alone suffer from: hydrolysis, high pour points, poor oxidative stability, self-polymerization, and other maladies.
Some of the vegetable oils available for conversion to finished esters are Castor oil, Corn oil, Cottonseed oil, Linseed oil, Palm oil, Palm kernel oil, Peanut oil, Rapeseed oil, Safflower oil, Sesame oil, Soybean oil, Sunflower oil, Calophyllum oil, Jatropha Curcus oil, Rice Bran oil, Sesame oil, Laranja oil, Rubber seed oil, Tung oil, Neem oil, Mahua oil, and Olive oil. There are over 65 candidate vegetable oils available for conversion
Vegetable oils and animal fats contain naturally occurring esters called, "triglycerides." Triglycerides are composed of "fatty acids" and complex alcohols (polyols) called "glycerols."
[In chemistry, an alcohol is any organic compound in which the hydroxyl functional group (-OH) is bound to a carbon. Ethanol or ethyl alcohol is one familiar alcohol. Glycerol is a polyol containing more than one hydroxyl group].
Triglycerides are the main culprits of poor vegetable oil lubricant performance and consist of three fatty acid molecules attached to one glycerol, a naturally occurring alcohol molecule.
Some of the "fatty acids" that may be found in vegetable oils and animal fats and in various concentrations (with their chemical name and carbon number) are: Lauric (Dodecanoic C12), Caproic (Hexoic C10), Caprylic (Octoic C8), Capric (Decoic C10), Myristic (Tetradecanoic C14), Oleic (C18:1), Linoleic (C18:2), Linolenic (C18:3), Palmitic (Hexadecanoic C16)), Stearic (Octodecanoic C18), Arachidic (Eicosanoic C10), Ricinoleic, Eurcic, and other, minor acids.
One of the drawbacks of triglycerides is their thermal instability due to the presence of a hydrogen atom on the β carbon on the glycerol backbone (also known as the β, "beta" hydrogen problem).
In order to improve the thermal stability of naturally occurring esters, we replace those bad glycerol's with selected, commercial polyols which do not possess the β-hydrogen. This can be accomplished through the process of transesterification. Transesterification in chemistry effectively means, "conversion of one type of ester to another."
One of those commercial polyols that can be used is Trimethylolpropane or TMP. So if we react TMP with Palm oil, we have as a result a Group V TMP ester, a most widely used ester in motor oils.
Since we did not have both questions answered in the same post, we cannot award any virtual prizes, but many of you answered one of the questions in one post. Good try folks!
