Question

3. In an article titled "Highly Selective Aldol Condensation Using Amine- functionalized SiO2-A1203 Mixed oxide under Solvent-free Condition” (Ref: A, Alireza et al, Chin. J. Chem. 2010, 28, 2074—2082. https://doi.org/10.1002/cjoc.201090346), it was reported that the jasminaldehyde vde (compound AA) was more preferentially produced than compound BB in aldol condensation reactions at various conditions. + o CHO 110 °C Compound AA Compound BB + & catalyst Temperature/C Conversion% Selectivity/% Jasminaldehyde (AA) 2-Pentyl-non-2-enal(BB) 25 63 100 50 80 99 1 3 80 92 97 110 100 97 3 160 100 90 10 Based on the molecular structures in the reaction scheme, suggest a reason for this selectivity. (5 points)

Answer 1

Hi there,

Have a closer look at compound-AA & compound-BB.

In compound-AA there is a benzene ring present, which is resonance stabilized and requires very high energy (greater than 36 kcal/mol) to become compound-BB (an open chain compound).

This trend can also be realized from temperature data, as temperature increases compound-BB percent also increases. In general aromatic compounds are more stable than open chain alkane, alkene compounds with similar molar mass.

Hope this helped you!

Thank You So Much!

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