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Monomer isomer governs polymerization Chemists at the Naval Air Warfare Center, China Lake, Calif., report a surprising isomer effect on whether a monomer undergoes polymerization or macrocyclization. Andrew P. Chafin and coworkers have been trying to synthesize polymers with nonlinear, second-order optical properties by incorporating p-amino-oc-cyanocinnamide units into them. After succeeding in polymerizing the o-phenylene monomer, they hoped to get even better alignment of polymer chains with an m-phenylene one. It was then that they observed cyclization instead [Macromolecules, 30, 1515 (1997)]. They begin by treating yV-ethylaniline with a^-dichloro-oxylene or the meta isomer to get the bis(ethylanilino) derivatives. They then add aldehyde groups. Each dialdehyde undergoes either a polymerizing or cyclizing Knoevenagel condensation with trans-l ,2-bis(cyanoacetamidoX7clohexane. The meta isomer forms no polymer, the ortho isomer forms no macrocyclic product. Stephen Stinson
THAT WAS THE PERFECT BATCH!
Chiral USA '97
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MARCH S I . 1997 C&EN
SYMPOSIUM SPEAKERS INCLUDE Dr Varinder Κ Aggarwal Dr Walter Brieden Dr Jean-Claude Caille Dr Michael ] Cannarsa Mr Carl ] Fearn Professor Tamio Hayashi Professor Eric Ν Jacobsen Dr Jim Lalonde Dr Scott A Laneman Professor Klaus Mosbach Professor Iwao Ojima Dr Ian O'Neil Dr Marina Protopopova Professor Yian Shi Professor Guy Solladié Dr P Stevenson Dr Nicholas J Turner Dr Leland Ο Weigel Professor Xumu Zhang
May 12-13th 1997 Boston, Massachusetts, USA Brochure requests, exhibitor details and delegate registrations: Brandon Associates, 547 Amersham Street, Suite 206, Nashua, NH03063 USA. Tel/Fax (603) 578-2669 Spring Innovations Ltd, 185A Moss Lane, Bramhall, Stockport SK7 1BA England. Tel +44 (0)161 440 0082 Fax +44 (0)161 440 9127 E-mail
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