Simple Lipids
Simple lipids are alcohol esters of fatty acids and include neutral fats and waxes . These are long chain fatty acid esters of trihydric alcohol glycerol . These fatty acids contain even number of carbon atoms and are both saturated and unsaturated carboxylic acids . Simple lipids are known as triglycerides or triacyl glycerols . Some of these are solids at room temperature , while others are liquids . Solids are known as fats and liquids are known as oils . The structure is represented as
R1 , R2 , R3 are the alkyl groups of the fatty acids . R1 , R2 , R3 may be same or different . Some examples are tripalmitin , tristearin and triolein . The fatty acids present are
tri palmitin - palmitic acid , C15H31COOH ( saturated )
tri stearin - stearic acid , C17H35COOH ( saturated )
tri olein - oleic acid , C17H33COOH ( unsaturated )
tri linolenin - linolenic acid , C17H29COOH ( unsaturated )
In most unsaturated acids , double bond is present at carbon - 9 . This is designated as `Delta`9 . Some acids contain more than one double bond . These double bonds are not conjugated .
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Some simple neutral lipids
If the fatty acids are different , the fat is called mixed fat . For example dipalmito stearin .
If two fatty acids anly are present , it is called diglyceride .
If the acids are attached to first two carbon atoms , the fat is called or `alpha` , `beta` - fat . If the acids bound to 1 & 3 carbon atoms , the fat is called 1,3 fat or `alpha` , `alpha`' fat .
If only one acid molecule is bound to the carbon atom , the fat is called monoglyceride . This is called 1-mono fat or 2-mono fat depending on the carbon .
The fat may contain different fatty acids . For example dipalmito stearin contains two palmitic acid molecules and one steraic acid molecule .
The fat may also contain one molecule each of oleic acid , palmitic acid and stearic acid . The fat is called `alpha` - acid , `beta` - palmito , `alpha` - stearin .
simple lipids - Important fatty acids
Some important fatty acids in fats are :
Acid | No of C-atoms | Formula | Nature | Fat |
Butyric acid Caproic acid Caprylic acid Capric acid Palmitic acid Stearic acid Arachidic acid Cerotic acid Linolenic acid Oleic acid | 4 6 8 10 16 18 20 26 18 18 | CH3(CH2)2COOH CH3(CH2)4COOH CH3(CH2)6COOH CH3(CH2)8COOH CH3(CH2)14COOH CH3(CH2)16COOH CH3(CH2)18COOH CH3(CH2)24COOH CH3(CH2)4CH=CH2OH=CH(CH2)7COOH CH3(CH2)7CH=CH(CH2)7COOH | Saturated Saturated Saturated Saturated Saturated Saturated Saturated Saturated Unsaturated Unsaturated | Butter Butter oil Coconut oil Coconut oil Animal fat Animal fat Groundnut oil Wool fat Cotton seed oil Animal fat |