Question

Draw the products formed when triacylglycerol A is treated with each reagent. Rank compounds A, B and C in order of increasing melting point.

a.${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$,${\mathbf{H}}^{\mathbf{+}}$

b. ${\mathbf{H}}_{\mathbf{2}}$(excess), $\mathbf{Pd}\mathbf{.}\mathbf{C}\mathbf{\to }\mathbf{B}$

c.${\mathbf{H}}_{\mathbf{2}}$(1 equiv), $\mathbf{Pd}\mathbf{.}\mathbf{C}\mathbf{\to }\mathbf{C}$

Short answer

Answer

a.

b.

c.

$$\begin{gathered} \mathrm{A}<\mathrm{C}<\mathrm{B} \\ 2\mathrm{double}\mathrm{bonds}1\mathrm{double}\mathrm{bond}0\mathrm{double}\mathrm{bond} \\ \mathrm{lowest}\mathrm{melting}\mathrm{intermediate}\mathrm{highest}\mathrm{melting} \\ \mathrm{point}\mathrm{melting}\mathrm{point}\mathrm{point} \end{gathered}$$

Step-by-step solution

Step-by-Step SolutionStep 1: Triacylglycerol

Triacylglycerols comprise esters acquired from glycerol and three fatty acids. They form the primary part of body fat and vegetable fat. Unsaturated fats constitute a class of triglycerides and possess a low melting point.

Melting point

The phase transformation from solid to liquid happens at a particular temperature termed the melting point. Pressure is one factor that impacts the melting point, and it is indicated at standard pressure.

Treatment of triacylglycerol A with different reagents

a. The treatment of compound A with ${\mathrm{H}}_2\mathrm{O}$, ${\mathrm{H}}^{+}$can be given as:

Treatment of compound A with ${\mathrm{H}}_2\mathrm{O}$, ${\mathrm{H}}^{+}$

b. The product obtained on the treatment of compound A with ${\mathrm{H}}_2$(excess) and Pd-C can be given as:

Treatment of compound A with ${\mathrm{H}}_2$(excess) and Pd-C

c.The product obtained on the treatment of compound A with ${\mathrm{H}}_2$(1 equiv) and Pd-C can be given as:

Treatment of compound A with ${\mathrm{H}}_2$(1 equiv) and Pd-C

The compound comprising more significant double bonds possesses a minor melting point. So, compound A, comprising two double bonds, has the lowest melting point.

Compound C will have an intermediate melting point, and compound B with zero double bonds has the highest melting point.

The compounds can be arranged in the order of increasing melting point as:

$$\begin{gathered} \mathrm{A}<\mathrm{C}<\mathrm{B} \\ 2\mathrm{double}\mathrm{bonds}1\mathrm{double}\mathrm{bond}0\mathrm{double}\mathrm{bond} \\ \mathrm{lowest}\mathrm{melting}\mathrm{intermediate}\mathrm{highest}\mathrm{melting} \\ \mathrm{point}\mathrm{melting}\mathrm{point}\mathrm{point} \end{gathered}$$