Melting points of Fatty Acids Flashcards
What factors influence the melting point of fatty acids?
The melting point of fatty acids is influenced by carbon chain length and the degree and type of unsaturation.
How does carbon chain length affect the melting point of fatty acids?
Increasing the carbon chain length increases the melting point due to stronger Van der Waals forces between longer chains. For example, C4 has a melting point of -3.4 °C, while C18 has a melting point of 69.3 °C.
Why do saturated fatty acids have higher melting points than unsaturated fatty acids?
Saturated fatty acids have higher melting points because they can pack closely together in a crystal lattice, leading to greater Van der Waals attractions, while unsaturated fatty acids have kinks from double bonds that disrupt packing.
How does the degree of unsaturation affect the melting point of fatty acids?
As the number of double bonds increases, the melting temperature decreases. For example, stearic acid (18:0) melts at 69.3 °C, oleic acid (18:1) at 13.4 °C, and linoleic acid (18:2) at -5.0 °C.
How does the configuration of unsaturated fatty acids affect their melting points?
Cis unsaturated fatty acids have lower melting points due to kinks in their structure, while trans unsaturated fatty acids have higher melting points. For instance, oleic acid (cis) melts at 13.4 °C, while elaidic acid (trans) melts at 52 °C.
Why is the position and distribution of fatty acids on glycerol important?
The positioning and distribution of fatty acids on glycerol can alter the melting profile of the fat, affecting its physical properties and behavior in different conditions.
