Question

5.) (5 pts) Draw the structure of the following triacylglycerols: (A) 1-Lauroyl-2-palmitoyl-3-myristoyl glycerol 3-0-64666, Vzzz *ISS CH3 (B) 1-Palmitoyl-2-olcoyl-3-myristoyl glycerol Hof-olece.co (C) 1- Arachidonoy -2-y-linolenoyl-3-palmitolooyl glycerol i CO-ELESS-SCS-C-CC- C13 (D) Tripalmitoleoyl glycerol -o-cac-c-c=c-c-c-cz o-c-c-c-cc-c-c-c-c-c-c-c=c-c-c-(tta. 12 P2 P2 HP2 H2 He it it h it He He. (E) 1-Arachidoyl-2-stearoyl-3-myristoyl glycerol cannoc-c-e-gc-core-c-c-c-c-c-c-c-c-c-ch nom 4-t-o-bac-c-c-c-c. c-c-c-oc-c-cc-cc- 12 V lete 212 A d-o-oce-c-c-c-c-c.e.c-c-c-c-Ch H hhhh it to 12 12 12 1h al 3 6.) (3 pts) Rank the triacylglycerols listed above from lowest melting point to the highest melting point
number 6

Answer 1

6)

As it is well known that saturated fatty acids esters (triacylglycerol) are well ordered and have stronger dispersion forces between their chains. These fatty acids have higher melting point and melts above room temperature while unsaturated fatty acid esters (triacylglycerol) are less ordered and the dispersion forces between unsaturated chains are weak. Therefore, these esters have low melting point. On increasing the number of double bonds, the melting point of fatty esters decreases.

Triacylglycerol A: This compound contains three saturated long chain fatty acids. (well-ordered and stronger dispersion forces)

Triacylglycerol B: This compound contains two saturated and one unsaturated (one double bond) long chain fatty acids (ordered and weaker dispersion forces than A).

Triacylglycerol C: This compound contains one saturated and two unsaturated (two double bond) long chain fatty acids (less ordered and weaker dispersion forces than B).

Triacylglycerol D: This compound contains three unsaturated (two double bond each = six double bond) long chain fatty acids (less ordered and weakest dispersion forces).

Triacylglycerol E: This compound contains three saturated and longer chain fatty acids than compound A. (well-ordered and stronger dispersion forces than compound A)

Thus, based on these concept, the order of melting point of these triacylglycerols is as

E > A > B > C >   D