Catalytic Use of Elemental Gallium for Carbon–Carbon Bond Formation
作者:Bo Qin、Uwe Schneider
DOI:10.1021/jacs.6b06767
日期:2016.10.12
The first catalytic use of Ga(0) in organic synthesis has been developed by using a Ag(I) cocatalyst, crownether ligation, and ultrasonic activation. Ga(I)-catalyzed C-C bondformations between allyl or allenyl boronic esters and acetals, ketals, or aminals have proceeded in high yields with essentially complete regio- and chemoselectivity. NMR spectroscopic analyses have revealed novel transient Ga(I)
Novel polymeric photocleavable photoinitiators are prepared by the hydrosilation reaction of an organosilicon hydride grafting agent which has a photoinitiating aromatic-aliphatic ketone derivative of at least one organo group, with a polymer having a plurality of unsaturated olefinic or acetylenic sites in the presence of a hydrosilation catalyst. Preferred polymers are butadiene or alkyl substituted butadiene polymers and copolymers and vinyl functional polyorganosiloxanes. The grafting agents have the formula (hv)--R.sup.8 --R.sup.5 --H wherein (hv) is a photoinitiating aromatic-aliphatic ketone group, R.sup.8 is selected from alkylene, alkenylene, alkylenoxy and oxy groups, and R.sup.5 is selected from ##STR1## the R.sup.6 groups are the same or different organo or halo groups and n is an integer.
The present invention is a UV curable composition of organic ethylenic unsaturated monomers and an organic polysiloxane polymer which has benzoin ether photoinitiator moieties bound to a silicon atom of the polymer. The compositions cure to form unsaturated monomer/polyorganosiloxane graft copolymers with improved lowtemperature flexibility, weatherability, insulating properties and impact strength. The silicone bound photoinitiators of the invention also increase cure efficiency of the compositions over compositions of unbound benzoin photoinitiators since multiple polymer chains are simultaneously grafted to the same silicone backbone.
The compositions of the invention are useful in adhesives, printing inks, photoresists, lithographics, and in coatings for plastics, wood, paper, etc., to produce protective films with good weather resistance and water repellancy.