To the lighthouse diaries
Related programme
In the Rough Science programme ‘To the Lighthouse’, the Rough Scientists build a lighthouse, Ellen has the task of manufacturing the fuel for the lamps. Zanzibar is full of coconut trees and so an obvious source of oil is the coconut to make coconut oil. But it isn’t a simple task of just squeezing out the oil!
To find out more about vegetable oils at molecular level and how one vegetable oil differs from one another and from animal fats, read the following extract from the second level OU course Our Chemical Environment (ST240).
Each of the triglyceride molecules is formed from glycerol and three carboxylic acids, the difference between the triglycerides of the three species results from each organism producing different carboxylic acids. The table here shows the structures of some of the common carboxylic acids, known as fatty acids, used in nature to make triglycerides, together with their names and origins.
Name | Carbon atoms | Structure | Type | Origin of name |
|---|---|---|---|---|
butyric | 4 | CH3(CH2)2COOH | saturated | Latin for butter is butyrium |
capric | 10 | CH3(CH2)8COOH | saturated | smell of goats (Latin for goat is caper) |
lauric | 12 | CH3(CH2)10COOH | saturated | from laurel |
myristic | 14 | CH3(CH2)12COOH | saturated | from nutmeg (genus Myristica) |
palmitic | 16 | CH3(CH2)14COOH | saturated | from palm oil |
stearic | 18 | CH3(CH2)16COOH | saturated | Greek for fat is stear |
oleic | 18 | CH3(CH2)7CH =CH(CH2)7COOH | mono- unsaturated | from oil (Latin, oleum) |
linoleic | 18 | CH3(CH2)4CH =CHCH2CH =CH(CH2)7COOH | poly- unsaturated | from linseed oil |
linolenic | 18 | CH3CH2CH =CHCH2CH =CHCH2CH =CH(CH2)7COOH | poly- unsaturated | Latin for flax is linum |
The chains are even because the building block from which fatty acids are made contains two carbons. So, however many building blocks are added together the chain always contains an even number of carbons.
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