Question

7) A nucleophile can attack acrolein either at the terminal carbon or at the carbonyl. Draw a) the mechanism for each addition as labeled, b) the inital intermediate formed, and c) the final product formed after neutralizing aqueous, mild acidic, workup. 1,2-addition a Nob) is also called 1,4-additiona) is also called d) Explicitly state why coulombic or FMO factors determine the course of each reaction. 1,4-addition: 1,2-addition: e) A hydride like NaBH4 would do a 1,4-addition or 1,2-addition? f) A thiolate would do a 1.4-addition or 1,2-addition? g) What theory explains the regioselectivity above (full name)? h) Build the acrolein FMO diagram from C= C i) Then draw and label the HOMO or LUMO of and C=O (similar to butadiene from 2 ethylenes) acrolein that dominates FMO reactivity. Find the values for localized charge density on acrolein and compare to relevant FMO coefficients. C2-01 Ca=c C4-C3-C2-01

Answer 1

NU NU NUD OH Addition A. LUMO of acco aerolinin In case of 1,4- addition Nuo can attack at B-Carbon because of larger coefficient. That is why 1,4- addition occurs. In case of 1,2-addition Nuo can attack carbonyl carbon atom due to developing positive change Character that is why carbonyl carbon acts as eletrophilie centre. e A hydride like NABHA would do 1,2-addition Na BA -OH HBH fy A thidate ion would do 1,4- addition, I In thiolate in st is soft centre. AB- carbon of acrolein is also soft end that is why soft-soft interaction leader leads 1,4- addition:

& Kinetically controlled product us thermodynamically controved product explain regio selectivity. E ng - LUMO 18 go 8 4 Homo v o → conjugated 2,ß-unsattused system