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Joined 2026-09-21 Message
Incoming links: Styrene
Build the phenethyl grignard reagent, use one portion to make a phenethyl-substituted ester, and add two further equivalents to that ester. Write ; the target is , so all three carbon substituents must be phenethyl, not benzyl.
hydroboration followed by oxidation of styrene gives : use in a suitable ether, followed by alkaline hydrogen peroxide. The Anti-Markovnikov addition regiochemistry is essential; acid-catalysed Markovnikov addition of water would give the wrong alcohol. Convert the primary alcohol to with phosphorus tribromide, then form with magnesium in dry ether. The organomagnesium reagent must be prepared and used without a protic solvent.
carboxylate one portion with carbon dioxide and acidify to obtain , then esterify with ethanol under acid catalysis to give . Treat the isolated ester with at least two equivalents of another portion of and then perform an aqueous acidic work-up:The first addition to the ester gives a ketone after ethoxide elimination; the second addition gives the tertiary alkoxide. Work-up supplies its OH proton. The extra central carbon comes from carbon dioxide, and each original styrene contributes one intact eight-carbon phenethyl unit. The resulting carbon count is , matching the target skeleton.
An approximately alternating styrene–maleic anhydride copolymer is produced. Its backbone alternates a segment with the two former alkene carbons of a maleic anhydride unit; those latter carbons remain connected to the intact five-membered cyclic anhydride ring.
Homolysis of benzoyl peroxide supplies initiating free radicals. Cross-propagation between electron-rich styrene and electron-poor maleic anhydride is favored over successive additions of the same monomer. Both carbon–carbon double bonds become backbone sigma bonds, without loss of a small molecule from each monomer. Initiator-derived benzoyloxy or phenyl fragments can occur at chain ends, with carbon dioxide formed when benzoyloxy free radicals decarboxylate.