1,1-Diphenylethylene Explained

1,1-Diphenylethylene is an aromatic hydrocarbon with chemical formula CH.

Properties

1,1-Diphenylethylene mediates the radical polymerization of methyl acrylate or styrene. Mediation by 1,1-Diphenylethylene generates low molecular weight polymer by a termination reaction.^[1] Additionally, because 1,1-Diphenylethylene has a lower pKa than styrene, it is an effective mediator in the anionic living polymerization of styrene-block-methyl methacrylate copolymers. Polystyrene homopolymers can be "capped" with 1,1-Diphenylethylene before adding methyl methacrylate, effectively adjusting the pKa of the active chain end so that 1,4-addition to methyl methacrylate is favored over 1,2-addition.^[2] Dibenzofulvene is an analogue of a 1,1-Diphenylethylene.^[3]

Synthesis

1,1-Diphenylethylene is technical prepared by alkylating benzene by styrene in presence of a zeolite beta and subsequent dehydrogenation.^[4]

styrene + benzene → 1,1-diphenylethane → 1,1-diphenylethylene + H

See also

• Dibenzofulvene
• Stilbene

Notes and References

1. Minjian Zhao . Zhifeng Fu . Yan Shi . Wantai Yang . Polymerization Mechanism in the Presence of 1,1-Diphenylethylene Part 2: Synthesis and Characterization of PMA and PSt . Macromolecular Chemistry and Physics . 2015 . 216 . 22 . 2202–2210 . 10.1002/macp.201500249 .
2. D. Freyss . P. Rempp . H. Benoît . Polydispersity of Anionically Prepared Block Copolymers . Journal of Polymer Science Part B: Polymer Letters. 1964 . 2 . 2 . 217–222. 10.1002/pol.1964.110020214 . 1964JPoSL...2..217F .
3. Tamaki Nakano . Kazuyuki Takewaki . Tohru Yade . Yoshio Okamoto . Dibenzofulvene, a 1,1-Diphenylethylene Analogue, Gives a π-Stacked Polymer by Anionic, Free-Radical, and Cationic Catalysts . Journal of the American Chemical Society. 2001 . 123 . 37 . 9182–9183. 10.1021/ja0111131 . 11552835 .
4. EP0742190 A1, BASF, 13 Nov 1996, Process for the Preparation of Diarylethanes