Tetramethylammonium chloride TMAC

The experiments were performed with single crystal (111) p-Si electrodes with a resistivity of about 5.5 ohm cm non-aqueous electrolytes were used consisting of absolute methanol containing tetramethylammonium chloride (TMAC) or acetonitrile containing tetraethyl ammonium perchlorate (TEAP). The flat-band potentials or p-Si in the two electrolytes were determined from Mott-Schottky plots (in the dark) in the depletion range of the p-Si electrode, from open-circuit photopotential measurements, and from the values of electrode potential at which anodic photocurrent is first observed in n-type Si electrodes. These three methods all yielded consistent flat-band potential values for p-Si of + 0.05V (vs SCE)... 

The DFA process has two reaction stages separated by an intermediates batch distillation stage. In the first halex reaction, the chlorine atoms of DCNB are replaced with fluorine atoms by reaction with potassium fluoride in a solvent, dimethylacetamide (DMAC). This forms 2,4-difluoronitrobenzene (DFNB), with the reaction accelerated by a catalyst, tetramethylammonium-chloride (TMAC). The second reaction stage is the catalytic hydrogenation of the distilled DFNB in methanol to form DFA. The catalyst is removed by filtration and the solvent is recovered by distillation from the finished product. 

When 0.5 M chloride ion (as tetramethylammonium chloride, TMAC) was added to the reaction mixture, the rate constant for the reaction shown in equation 9.66 increased by a factor of 5, and the product distribution had a much greater proportion of 69 and 70 (equation 9.66). 

An entirely different order of reactivity was observed when dry-blending was used in pretreatment. These results may be partially due to problems in dispersing the catalysts in dry cellulose powder. Tetramethylammonium chloride (TMAC) is very soluble in water and can be dispersed using a minimum of water. 

The reaction sequence leading to nylon 4 from 2-pyrrolidone, KOH, C02> and tetramethylammonium chloride (TMAC) is shown in Scheme 1. 

Fluka http //www.sigma-aidrich.com] Sachem http //www.sacheminc.com] Xinchem http //WWW. finechemnet. com Tetramethylammonium chloride CAS 75-57-0 EINECS/ELINCS 200-660-6 Synonyms TMAC N,N,N-Trimethylmethanaminium chloride Ciassification Quaternary ammonium salt Empihcai C4H12CIN Formula (CH3)4N Cr... 

TMA. See Trimellitic anhydride Tri methyl amine TMAB. See Tetramethylammonium bromide TMAC TMAC. See Tetramethylammonium chloride... 

TMAC = tetramethylammonium chloride, TBAB = tetrabutyl-ammonium bromide, TBPB = tetrabutylphosphonium bromide. 

Cellulose Pretreatment. A. Dry-Blend Technique. Powdered cellulose (36.0 g 0.20 eq) was blended while 2.0 g (0.018 mol) of tetramethylammonium chloride in 2 ml of water was sprayed into the powder using a fine-needled syringe. A solution of 30 g sodium hydroxide in 30 ml H2O was heated to boiling the hot solution was added slowly to the TMAC treated cellulose and blending was continued for 0.5 hr. A total of 100 g of pretreated cellulose powder is obtained. 

Interestingly, TMAC, although it is insoluble in 2-pyrrolidone, apparently reacts with py-K/C02 and influences the outcome of the polymerization. On the other hand, other insoluble onium salts, such as tetramethylammonium perchlorate, tetrafluoro-borate, and hexafluorophosphate, are unreactive and give approximately the same conversion and molecular weight as the control run without onium salt. Anong the soluble onium salts tested, tetraethylammonium chloride and tetramethylammonium acetate are quite effective to increase conversion and molecular weight but are not better than the insoluble TMAC (Table IV). 

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