Diphenylmethyl potassium

A combination of anionic and ATRP was employed for the synthesis of (PEO-b-PS) , n = 3, 4 star-block copolymers [148]. 2-Hydroxymethyl-l,3-propanediol was used as the initiator for the synthesis of the 3-arm PEO star. The hydroxyl functions were activated by diphenylmethyl potassium, DPMK in DMSO as the solvent. Only 20% of the stoichiometric quantity of DPMK was used to prevent a very fast polymerization of EO. Employing pentaerythritol as the multifunctional initiator a 4-arm PEO star was obtained. Well-defined products were provided in both cases. The hydroxyl end groups of the star polymers were activated with D PM K and reacted with an excess of 2-bromopropionylbro-mide at room temperature. Using these 2-bromopropionate-ended PEO stars in the presence of CuBr/bpy the ATRP of styrene was conducted in bulk at 100 °C, leading to the synthesis of the star-block copolymers with relatively narrow molecular weight distributions (Scheme 72). 

The preparation of the potassium alcoholate requires much care. Metalation of the alcohol is carried out to completion without attack of the double bond by means of diphenylmethyl potassium in THF solution. Excess alcohol present in the subsequent polymerization system would act as a transfer agent. 

PEO prepared by anionic polymerization using the monofunctional initiator ((diphenylmethyl)potassium) has one -OH end group leading to the formation of linear-dendritic diblock copolymers (Scheme 102). 

The ability of anionic polymerization to polymerize macromonomers has been demonstrated. co-(Methacryloyloxy)-PS macromonomers could be homopolymerized anionically to high yield using diphenylmethyl potassium as an initiator. Similar results could be obtained for co-styryl-PS macro monomers. These cylindrical bmsh species served as models for physicochemical studies. The major difficulty of this reaction... 

Methylfluorene has been prepared by cleavage of ethyl 9-methyl-9-fluorenylglyoxylate,4 by the decarboxylation of 9-methylfluorene-9-carboxylic acid,4 by the decarboxylation of 9-fluorenylacetic acid,6 by the cleavage of 9-methyl-9-acetyl-fluorene with alcoholic potassium hydroxide or soda-lime,6 by the reduction of 9-methyl-9-fluorenol with hydriodic acid in acetic acid,7 by the reaction of 9-fluorenyllithium 8 or -sodium 9 with methyl iodide or methyl sulfate,9 by the cyclization of diphenylmethyl carbinol over platinum-on-carbon at 300°,10 by the reaction of ethyl 9-methoxymcthyl-9-fluorcnylcarboxylate,11 by the diazotization and heating of 2-ethyl-2-aminobiphenyl,12 by the dehydration and then reduction of 9-mcthyl-9-fluorcnol,13... 

Polyethylene oxide)macromonomers were also prepared by reaction of methacryloyl chloride with living monofunctional poly(ethylene oxide) I6) the polymerization of which can be efficiently initiated by diphenylmethyl potassium25 or by potassium alkoxides 26 >. In the latter case care must be taken to avoid any excess of alcohol which would play the role of a transfer agent and impede the macromonomer synthesis. The obtained macromonomers... 

Treatment of diphenylacetonitrile in toluene with sodium amide and 2-chloro-pyrazine gave 2-(C-cyano-C,C-diphenylmethyl)pyrazine (1021), and 2-vinylpyrazine with phenylacetonitrile and sodium heated at 120-130° for 10 minutes gave 2-(3 -cyano-3 -phenylpropyl)pyrazine (731). 2-Amino-5-bromomethyl-3-cyano-pyrazine with sodium hydride and methyl cyanoacetate in tetrahydrofuran formed the dialkylated product (56) (1031). 2-Amino-3-mercapto-5,6-dimethylpyrazine in methanol with potassium hydroxide and chloroacetonitrile gave 2-amino-3-cyanomethyIthio-5,6-dimethylpyrazine (1229), and 2-carboxypyrazine refluxed with chloroacetonitrile and triethylamine in ethyl acetate for 45 minutes gave the cyanomethyl ester (1317). 2-Hydroxy 5-methyl-3-propylpyrazine with cyanogen halides in aqueous sodium hydroxide-dimethylformamide at 0-5° gave l-cyano-5-methyl-2-oxo-3-propyl-l, 2-dihydropyrazine (1123). 

The kinetics and products of isomerization of methyl 2-[(4-diphenylmethylene)-2,5-cyclohexadienyl]-2-methylpropanoate to methyl p-diphenylmethyl-a,a-dimethylphenylacetate in / r/.-butyl alcohol solutions of DA BCO and methanol solutions of potassium methoxide, viz. ... 

Preparation by reaction of dimethyl sulfate with 2,4-di-hydroxy-6-methoxy-5-(diphenylmethyl)ace-tophenone in the presence of potassium carbonate in refluxing acetone (69%) [2432],... 

Although a-phenylisopropyl potassium reacts with pyridine sodium and potassium alkyls have not been much applied in pyridine chemistry. Diphenylmethyl sodium and related compounds fail to react with... 

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