CD 13.6 Oils and Fats

Yo. 13.6 is all about the oils and the fats. The video above is pretty helpful, just don't get sidetracked watching all the weight loss videos it recommends after watching, not that that happened to me...

Anyways, most fats and oils are esters of glycerol:



Condensation reactions join carboxylic acids with long hydrocarbon chains to the glycerol molecule.
For example, palmitic acid can be joined onto the glycerol molecule to form a fat.
Natural triesters are often mixed triesters, meaning they have different fatty acids.

Oils and fats can be spit apart by hydrolysis. This is usually one by heating the oil/fat with concentrated sodium hydroxide, which forms glycerol and an acid salt.

Fats tend to be saturated molecules (no double bonds) which can be packed tightly together by intermolecular bonds. This means that they are harder to break apart, and so they are solid.

Oils tend to be unsaturated, with double bonds, causing it to have a kink in the chain. This means that the intermolecular bonds will be weaker, and it's more likely to be a liquid.

You can convert oils to fats by removing the double bonds. The reaction that does this is called hydrogenation, where hydrogen is passed through heated oil with a nickel catalyst. You can do this reaction to different extents, you can do it until is hardens, or even until it hardens so much that it is brittle. So depending on what you want, you can control how much hydrogenation occurs. In Chemical Ideas they give the example of margarine.

Answers to the past exam questions are here. Looking through the past exam papers, fats and oils does come up, but not in much detail. It's mainly the 'draw the structure' questions and hydrolysis of fats and oils.