Question

7. Antioxidants for polyolefins (polyethylene, polypropylene...), are frequently alkylated phenols. They prevent radical induced formation of peroxides, which can eventually lead to polymer chain scission reactions. When these polymers are used outside in sunlight, the phenols are decomposed by excited state reactions. Attenuation of this photochemical decomposition has been an interesting challenge. One solution was based on building a molecule whereby the excited phenol moiety could transfer its excess energy to another group in the molecule that was not prone to excited chemical change. Several constraints on such a donor-acceptor molecule boiled the "target" down to compound A (below). Compound A can be made using textbook chemistry revolving around electrophilic aromatic substitution. Starting materials are phenol, benzoic acid, p-methoxyphenylacetic acid, acyl halides, and isobutylene. In fact, a synthesis of compound A was outlined by a sophomore 'orgo" student who was working as a laboratory assistant for a group of Ph.D. chemists. He was studying electrophilic substitution reactions at the time. Can you mimic his successful approach? Using reactions learned in class (chapters 7-20 of our textbook), propose a forward synthesis of compound A. Be sure to include any additional reactants or reagents that may be needed. Note that some protecting group chemistry may be required, since AICl, will react with alcohols/phenols to make aluminum alkoxides. (0.8 pts) OH он но CH2(CH2hCH3 compound A

Answer 1

Clemmenson reduction Friedel-Crafts acylation Zn(Hg) CH. MeONa MeOH AICl3 HCI phenol anisole (CH2)nCH3 Friedel Crafts alkylation AICI Clemmenson reduction OMe OMe Me O CI Zn(Hg) HCI AICI (CH2)nCH3 (CH2)nCH3 Friedel-Crafts acylation CI Friedel-Crafts acylation AICl3 O-demethylation OMe он CH2Cl2 (CH2)nCH3 (CH2)nCH3 The acid chlorides can be synthesized by reacting corresponding acids with thionyl chloride in presence of pyridine Me SOCl2 SOCI2 он pyridine pyridine он CI