Reduction of poly

Reduction of poly(vinyl chloride) with lithium aluminium hydride. 

Reduction of Poly(2-cyano-l,3-phenylene arylene ether), 20 Twenty-five mL of a 1.0 M solution of lithium aluminum hydride (LAH) in THF was cooled to 0° C before adding a solution of 1.64 g (5.0 meg) of 20 in 120 mL of THF. The resultant slurry was stirred for 24 h at 0° C, refluxed for 1 h, recooled to 5° C, and the excess LAH decomposed with 2 mL of water. The volume of the solution was reduced to 25 mL before pouring the mixture into 500 mL of 5% HC1 to dissociate the amine aluminum salt complex and precipitate the polymer. The polymer was recovered by filtration, reslurried in 20 mL of water and the pH adjusted to 9.0 with NaOH. After recovery of the neutralized polymer was recovered, it was dried in vacuo redissolved in CHC13, and reprecipitated using water as the nonsolvent. Final drying in vacuo for 24 h at 35° C left 1.2 g (72.3%) of poly[oxy-l,4-phenylene-(l-methylethylidene)-l, 4 -phenylene-oxy-(2"-aminomethyl)-l",3"-phenylene], 21, [n] (CHCI3) 0.3 dl/g. 

The most interesting aminomethyl derivative of condensation polymers that we have prepared to date Is derived from direct reduction of poly(2-cyano-l,3-phenylene arylene ether), 20. Enchainment of benzonitrile repeat units Is accomplished by coupling 2,6-dichlorobenzonitrile with the potassium salt of bisphenol-A copolymers with lower nitrile contents can be produced by copolycondensation of bisphenol-A, 2,6-dichlorobenzonitrile and 4,4 -dichlorodiphenyl sulfone.21 The pendent nitrile function provides an active site for further elaboration. 

Tri-rirbutyltin Hydride Reduction of Poly (vinyl chloride)... 

In spite of the high effort focused on the carbon electrochemistry, very little is known about the electrochemical preparation of carbon itself. This challenging idea appeared in the early 1970s in connection with the cathodic reduction of poly(tetrafluoroethylene) (PTFE) and some other perfluorin-ated polymers. The standard potential of the hypothetical reduction of PTFE to elemental carbon ... 

Reduction of poly(butyl)naphthalenes with sodium-potassium alloy in ether causes their isomerization (Goldberg et al. 1976). The reduction of l,3,6,8-tetra(tcrt-butyl)naphthalene produces an anion-radical, which disproportionates yielding the initial tetrabutylnaphthalene and corresponding dianion (Scheme 6.32). 

Immobilization of the colloidal catalyst on resins was studied in order to use them repeatedly as stable solid catalyst. The citric acid reduction of poly(hydroxyethyl-methacrylate) containing H2PtCl4 yielded immobilized Pt colloids which are dispersed in that polymer57. It could be used as H2 generating catalyst repeatedly without activity loss in the system of EDTA-Ru(bpy)3 + -MV2 +. ... 

The reduction and oxidation of radicals are discussed in Chapter. 6.3-6.5. That in the case of radicals derived from charged polymers the special effect of repulsion can play a dramatic role was mentioned above, when the reduction of poly(U)-derived base radicals by thiols was discussed. Beyond the common oxidation and reduction of radicals by transition metal ions, an unexpected effect of very low concentrations of iron ions was observed in the case of poly(acrylic acid) (Ulanski et al. 1996c). Radical-induced chain scission yields were poorly reproducible, but when the glass ware had been washed with EDTA to eliminate traces of transition metal ions, notably iron, from its surface, results became reproducible. In fact, the addition of 1 x 10 6 mol dm3 Fe2+ reduces in a pulse radiolysis experiment the amplitude of conductivity increase (a measure of the yield of chain scission Chap. 13.3) more than tenfold and also causes a significant increase in the rate of the chain-breaking process. In further experiments, this dramatic effect of low iron concentrations was confirmed by measuring the chain scission yields by a different method. At present, the underlying reactions are not yet understood. These data are, however, of some potential relevance to DNA free-radical chemistry, since the presence of adventitious transition metal ions is difficult to avoid. 

Benzo-1,3-ditellurole 54 was prepared in 40-47% yield by reacting dibro-momethane with disodium benzene-o-ditellurolate in ethanol, the latter generated in situ through reduction of poly(o-phenylene)ditelluride 55 with NaBH4 (88KGS1144 91 MI 1). The polymeric ditelluride 55, in turn, was obtained from a two-step procedure starting with bis-(o-trimethylsilyl)-benzene. 

Dilithium or disodium areneditellurolates were alkylated with methyl iodide3, dimethyl sulfate4, or diethyl sulfate4. The areneditellurolates were prepared from the corresponding dibromides and tert.-butyl lithium in tetrahydrofuran and treatment of the resulting mixture with powdered tellurium3, or by the reduction of poly(l,4-phenylene ditellurium) with sodium borohydride in ethanol/benzene4. 

Putrescine and Cadaverine.— The poly-amines may be obtained by the reduction of poly-nitro compounds or poly-cyanogen compounds (pp. 70, 75). In the former case the amine has the same number of carbons as the nitro compound but in the latter case the amine has two more carbons than the radical of the di-cyanogen compound. The usual method of formation, however, is the one already used in preparing the mono-amines, viz., from the corresponding halogen compound by action of ammonia. 

Kublanovskiy, V.S. Litovcenko, K.I. Stezeryanskiy, E.A. Shpak, A.P. Mechanism of electrochemical reduction of poly(chlorotrifluoroethylene). Dokl. Akad. Nauk Ukr. SSR Ser. B Geol. Khim. Biol. Nauki 1989, 36-39. 

Stezeryanskiy, E.A. Litovcenko, K.L Kublanovskiy, V.S. Effect of the electrolyte cation on electrochemical reduction of poly(chlorotrifluoroethy-lene). Ukr. Khim. Zhur. 1989, 55, 826-829. 

Hydrogen sulfide derivatives can also be used for partial reduction of poly-nitro compounds. 

The reduction of poly(vinylacetophenone) with lithium aluminum hydride (LiAlH4) and quinine led to a product which was estimated to contain about 9% of (+ )-poly-[4-(2-hydroxyethyl)styrene. This asymmetric reduction is described in Preparation 13-2. 

IR spectroscopy is well suited to monitor the progress of post-functionalization reactions—for example, for the quaternization of P4VP (see Figure 4.IB) or the hydrolysis or reduction of poly(vinylfor-mamide) to yield primary amines (see Figure 4.1C) [1,2]. Moreover, the presence of undesired by-products such as boric acid after using borane/THF adducts for the aforementioned reduction reaction can be detected. 

A. Richard, A. Margaritis, Kinetics of molecular weight reduction of poly (glutamic acid) by in situ depolymerization in cell-free broth of Bacillus subtilis, Biochem. Eng. J. 30 (2006) 303-307. 

The results, however, are inconclusive, because combustion analyses fail to match the theoretical composition for poly(methallyl alcohol). It is impossible to teU to what extent the reduction takes place. Inconclusive results are also obtained in similar reductions of poly(methyl acrylate) in mixtures of tetrahydrofiuan and benzene. When a product of such reduction is acetylated with acetic anhydride in pyridine as follows ... 

An alternative method for the preparation of poly(n-propylenimine) and poly(n-butylenimine) was reported by Fischer et ah, based on the reduction of poly(p-alanine-N-carbo Q anhydride) and poly(pyrrolidone) (polyamide-4), respectively. The same methodology can be utilized for the preparation of PHAIs by the reduction of any polyamide, e.g. nylon, with borane" or sodium borohydride. ... 

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