Dimethylformamide solution

The dimethylformamide solution may be used repeatedly if each time the volmne is reduced by the distillation of the remaining water. After two runs the accumulated sodium chloride should be removed by filtration. 

Reaction of Na2Se and Na2Sc2 with Se in the presence of ethanolic solutions of tetraalkyl-ammonium halides and catalytic amounts of I2 yields dark green or black crystalline polyselenides (jc = 3,5-9) depending on the conditions used and the particular cation selected. Tetraphenylphosphonium salts and crown ether complexes of alkali or alkaline earth cations in dimethylformamide solution can also be used. " )... 

Quinoxaline-2,3-dithione (2,3-dimercaptoquinoxaline) (90) forms chelates with several transition elements and is used as a colorimetric agent for the detection and quantitative estimation of nickeT and also for the quantitative estimation of palladium. " Nickel gives a pink coloration with (90) in ammoniacal solution, and palladium an orange-red color in AA-dimethylformamide solution containing a little hydrochloric acid. Spectrophotometric studies of the chelate compounds of (90) with Ni(II), Co(II), and Pd(II) in alkaline solu-... 

After this reaction-time, the evolution of hydrogen is ceased. Then there are added successively 60 parts dimethylformamide and 8 parts of p-chlorobenzylchloride and stirring and refluxing is continued for another two hours. The tetrahydrofuran is removed at atmospheric pressure. The dimethylformamide solution is poured onto water. The product, 1-[2,4-dichloro-/3-(p-chlorobenzyloxy)phenethyl] imidazole, is extracted with benzene. The extract is washed with water, dried, filtered and evaporated in vacuo. From the residual oily free base, the nitrate salt is prepared in the usual manner in 2-propanol by treatment with concentrated nitric acid, yielding, after recrystallization of the crude solid salt from a mixture of 2-propanol, methanol and diisopropylether, 1-[2,4-dichloro-/3-(p-chlorobenzyl-oxylphenethyl] imidazole nitrate MP 162°C. 

Thymol blue is used extensively as an indicator for titrations of substances acting as acids in dimethylformamide solution. It is used as a 0.2 per cent w/v solution in methanol with a sharp colour change from yellow to blue at the end point. 

A poly(L-lysine) dendrimer 23 which carries 16 free-base porphyrins in one hemisphere and 16 Zn porphyrins in the other has been synthesized and studied in dimethylformamide solution [54]. In such a dendrimer, energy transfer from the Zn porphyrins to the free-base units can occur with 43% efficiency. When the 32 free base and zinc porphyrins were placed in a scrambled fashion, the efficiency of energy transfer was estimated to be 83% [55]. Very efficient (98%) energy transfer from Zn to free-base porphyrins was also observed in a rigid, snowflake-shaped structure in which three Zn porphyrin units alternate with three free-base porphyrin units [56]. 

In dimethylformamide solution, platinum exchange between Pt(en)Br2 and Pt(en)Br4 has been found to be light-sensitive and catalysed by bromide ions. In the absence of light, a value < 1.33 x 10" l.mole . sec was obtained for the observed rate coefficient (25 °C) from data obtained by the isotopic method (i95pt) separation using an ether precipitation of Pt(en)Br2. The bridge mechanism was thought to occur... 

The electrocatalysts for oxygen reduction were prepared as follows. These complex compounds were inoculated onto the carbon (AG-3, BET area near 800 m2/g) by means of adsorption from dimethylformamide solutions. The portion of complex compound weighed so as to achieve 3% of Co content was mixed with the carbon, then 5 ml of dimethylformamide per 1 g of the carbon were added and the mixture was cured at room temperature for 24 hours. Series of samples obtained were thermally treated (pyrolyzed), and the resulting grafted carbons were tested as electrode materials in the reaction of molecular oxygen reduction. 

Perel man and Evstratova (65) titrated hydralazine hydrochloride in dimethylformamide solution to a potentio-metric end-point with sodium methoxide solution. 

Experiments conducted with dimethylformamide solutions at 20°C have shown that the "auto-acceleration index" 3 indeed decreases upon dilution and becomes 1.0 in a 40 per cent monomer solution where the polymer still precipitates (18). The data are summarized in Table II. 

The complex Os(OEP)N2(DMF) [iii]has a distinctly lower NN-stretching frequency than the similar Os(OEP)N2(THF) [31a]. Indeed, [31b] can be isolated and electrochemically traced in dimethylformamide solutions, while this is impossible with the much more labile [31a], However, any nitrogenous base displaces dinitrogen in [31a] to yield the corresponding osmochromes [29], Obviously, a strong a-donor expels the weak a-donor, N2, tram to itself. 

Chromium(II) sulfate is a versatile reagent for the mild reduction of a variety of bonds. Thus aqueous dimethylformamide solutions of this reagent at room temperature couple benzylic halides, reduce aliphatic monohalides to alkanes, convert vicinal dihalides to olefins, convert geminal halides to carben-oids, reduce acetylenes to /raw5-olefins, and reduce a,j3-unsatu-rated esters, acids, and nitriles to the corresponding saturated derivatives. These conditions also reduce aldehydes to alcohols. The reduction of diethyl fumarate described in this preparation illustrates the mildness of the reaction conditions for the reduction of acetylenes and o ,j8-unsaturated esters, acids, and nitriles. 

Chromium(II) perchlorate is the salt of choice for preparing the en complex in dimethylformamide solution. At comparable concentration levels chromium(II) sulfate is insoluble, and the <-.lu-omium(lI) chloride - is only partially soluble in the i-( a< tion solution. 

The synthesis of the basic skeleton of 1-benzylisoquinoline alkaloids has been reported by Uff et al. 15) starting from isoquinoline and benzyl chloride (Scheme 5). The preparation of Reissert compound iV-benzyl-l-cyano-l,2-di-hydroisoquinoline (4) was performed in a dichloromethane-water two-phase system with potassium cyanide and benzoyl chloride in about 64-69% yield. The deprotonation of 4 with sodium hydride in dimethylformamide solution, the subsequent alkylation with benzyl chloride, and the final alkaline hydrolysis could be performed as a one-pot reaction sequence to supply 1-benzylisoquinoline (25) in an overall yield of 75-84%. 

Formate production has also been reported for electropolymerized films of [Co(4-vinylterpyridine)2] " on glassy carbon electrodes in dimethylformamide solutions [63]. Interestingly, the product of this same catalytic system in aqueous solutions is formaldehyde [81]. Other heterogeneous systems that produce formate include Cd, Sn, Pb, In, and Zn electrodes in aqueous media [12] (see also Vol VII 5.2.3). It is likely that the pathway to formate formation on metal electrodes follows the sequence of M—H bond formation followed by CO2 insertion to form a M—0C(0)H species followed by desorption from the electrode surface. 

The same plot constructed with the Dr/Dr0 data from depolarized dynamic light scattering is shown in Fig. 27b. The data points of Kubota and Chu [131] for dimethylformamide solutions come closer to the theoretical curve than those... 

Fig. 13. Scanning electron micrograph of polyacrylonitrile fibrils formed by spraying a 0.05 wt % polyacrylonitrile in dimethylformamide solution into C02 through a 50-/mi inner diameter, 18-cm-long nozzle at a temperature of 40°C, density of 0.66 g/mL, and solution flow rate of 0.36 mL/min (118).

The fully aromatic diquaternary system 81 is prepared by acid ring closure of the salt (79) obtained by quaternization of 1,10-phen-anthroline with bromoacetaldehyde followed by dehydration of the resulting hydroxy diquaternary salt (80) with thionyl chloride.310,311 The salt 81 is unstable in aqueous solution above a pH of about 5.0. In the pH range 3.3-5.0 it is reduced by a one-electron transfer to the corresponding radical cation at a potential (E0) of —0.12 volt.311 Its reduction in dimethylformamide solution has also been studied.15,307 Substituted derivatives of 81 have been prepared.312... 

On the other hand, the condensation of isothiocyanates 2, 30, and 31 with 6-aminopenicillamic acid (167), as well as ampicillin (168), in tetrahy-drofuran or N,N-dimethylformamide solution in the presence of triethyl-amine,90 led to formation of only the corresponding thioureides 169-174. 

When pentafluororutrobenzene reacts with ortho- or para-aminophenol in dimethylformamide solution containing sodium hydroxide, the 4-fluonne is replaced. Either the amino or the hydroxyl function of the aminophenol can act as the nucleophile depending on the reaction conditions [67] (equation 35)... 

Several authors have recently adapted the sulfonium elimination route to prepare poly(2,5-thienylenevinylene) and reported high conductivities (200 S cm-1) on doping 244 245). In this case the sulfonium precursor is insoluble in water but can be cast from dimethylformamide solution. Jen et al. 246) report an alternative route involving a water-soluble precursor which eliminates HC1 and tetrahydrothiophene. 

The checkers found that vigorous mechanical stirring was required because of the viscosity of the dimethylformamide solution at -78°C otherwise, diminished yields were observed. 

The t-butyldimethylsilyl ether (TMBS-ether), formed from the alcohol with t-butyldimethylsilyl chloride in the presence of imidazole in dimethylformamide solution,84 is more stable to hydrolysis than the TMS-ether (see also Section 4.2.66, p. 461). Deprotection is readily effected by treatment with 2-3 equivalents of tetrabutylammonium fluoride in tetrahydrofuran at 25 °C,84a or tetrabutyl-ammonium chloride and potassium fluoride dihydrate in acetonitrile.84b... 

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