Search Results - (Author, Cooperation:M. J. Greene)

2014-05-09

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Amacrine Cells/cytology/physiology/ultrastructure ; Animals ; Artificial Intelligence ; *Brain Mapping ; Crowdsourcing ; Dendrites/metabolism ; Mice ; *Models, Neurological ; Motion ; Neural Pathways/*physiology ; Presynaptic Terminals/metabolism ; Retina/*cytology/*physiology ; Retinal Bipolar Cells/cytology/physiology/ultrastructure ; *Spatio-Temporal Analysis

0887-624X

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

A variety of simple alkyl and aryl isocyanides have been polymerized using 0.5% NiCl2 in ethanol as a catalyst. The resulting poly(iminomethylenes) have been characterized by carbon-13 NMR spectroscopy and their polystyrene-equivalent molecular weights have been determined by gel permeation chromatography. Straight chain aliphatic isocyanides having from three to ten carbon atoms in the chain form readily solyble polymers having molecular weights (Mw) in the general range 10,000 to 30,000. Neopentyl isocyanide unlike tert-butyl isocyanide forms an insoluble polymer. A number of new soluble aryl isocyanide polymers have been obtained. However, aryl isocyanides having a single alkyl substituent (CH3, C2H5, CF3) in the ortho position give only insoluble polymers, whereas aryl isocyanides having alkyl substituents in both ortho positions (e.g., 2,6-(CH3)2C6H3NC and 2,4,6-(CH3)3C6H2NC) fail to polymerize under these conditions. The highest molecular weight soluble aryl isocyanide homopolymer is obtained from 3-CH3OC6H4NC(Mw = 26,000). The trimethylsilyl substituted isocyanide (CH3)3SiCH2CH2NC has been obtained from LiCH2NC and (CH3)SiCH2Cl and gives a brown soluble homopolymer with a molecular weight (Mw) of 19,000.

1 Ill.

Electronic Resource

0887-624X

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Copolymerization of an isocyanide giving an insoluble homopolymer with another isocyanide giving a soluble homopolymer in ethanol solution using 0.5-1% of a nickel (II) catalyst in many cases gives a soluble copolymer containing pendant groups arising from both isocyanides. Thus, methyl isocyanide, which gives an insoluble homopolymer, gives chloroform-soluble copolymers incorporating 39-44% of pendant methyl groups when copolymerized with equimolar amounts of tert-butyl isocyanide or several aryl isocyanides. Similarly, cyclohexyl isocyanide, which also gives an insoluble homopolymer, gives chloroform-soluble copolymers incorporating 43-59% of pendant cyclohexyl groups when copolymerized with equimolar amounts of several aryl isocyanides. The compositions, chloroform solubilities, and polystyrene equivalent molecular weights are given for 33 different copolymers obtained by copolymerizations of various equimolar binary mixtures of the monomers CH3NC, (CH3)3CNC, cyclo-C6H11NC, C2H5NC, CH3CH=CHNC,(CH3)2C=CHNC, 2,4,6-(CH3)3C6H2CH=CHNC, C6H5CH(CH3)NC, CH2=CHNC, (CH3)3CCH=CHNC, C6H5NC, 2- and 4-CH3C6H4NC and 2-, 3-, 4-CH3OC6H4NC using the nickel (II) catalyst system.

2 Ill.

Electronic Resource