Nitromethane reactant

The kinetic effect of increased pressure is also in agreement with the proposed mechanism. A pressure of 2000 atm increased the first-order rates of nitration of toluene in acetic acid at 20 °C and in nitromethane at 0 °C by a factor of about 2, and increased the rates of the zeroth-order nitrations of p-dichlorobenzene in nitromethane at 0 °C and of chlorobenzene and benzene in acetic acid at 0 °C by a factor of about 559. The products of the equilibrium (21a) have a smaller volume than the reactants and hence an increase in pressure speeds up the rate by increasing the formation of H2NO. Likewise, the heterolysis of the nitric acidium ion in equilibrium (22) and the reaction of the nitronium ion with the aromatic are processes both of which have a volume decrease, consequently the first-order reactions are also speeded up and to a greater extent than the zeroth-order reactions. 

Nitromethane has been used as a solvent for molecular bromination297. The bromination of polymethylbenzenes in nitromethane, acetic acid, and 1 1 mixtures of these solvents at 30 °C, showed that rates were much faster (about 330-fold) in nitromethane than in acetic acid. With nitromethane, in the bromine concentration range 0.01-0.02 M, the reaction was third-order in bromine. The relative deactivating effects of m-halogen substituents were measured in terms of the time taken for 10 % reaction to occur, and these values are given in Table 71 from which the relative reactivities in the different solvents are apparent the deactivating effects of the m-nitro substituent were obtained by comparison with the reactivity of chloromesitylene at different concentrations (0.035, 0.055 M) of reactants. The results for the nitro compounds were interpreted in the same way... 

The condensation of arylsulfonyl acetonitriles 369a-c with 22a proceeds via addition of the in-situ formed anion 370 to the arylsulfonyl acetonitriles 369 to afford the dimers 371, in 69-94% yield, and hexamethyldisiloxane 7 [136]. Furthermore, y9-dicarbonyl compounds such as ethyl acetoacetate 372 a or ethyl benzoyl-acetate 372b are O-silylated by 22 a or 22 c to rather stable alkyl 3-O-trimethylsilyl-oxycrotonoate 373a and alkyl 3-0-trimethylsilyloxy-3-phenyl acrylate 373b [130]. Aliphatic nitro compounds such as nitromethane are O-trimethylsilylated and further transformed into oligomers [132] (cf Section 7.6) and are thus unsuitable reactants for silylation-C-substitutions (Scheme 4.50). 

The catalytic application of clays is related closely to their swelling properties. Appropriate swelling enables the reactant to enter the interlamellar region. The ion exchange is usually performed in aquatic media because the swelling of clays in organic solvents, and thus the expansion of the interlayer space, is limited and it makes it difficult for a bulky metal complex to penetrate between the layers. Nonaqueous intercalation of montmorillonite with a water-sensitive multinuclear manganese complex was achieved, however, with the use of nitromethane as solvent.139 The complex cation is intercalated parallel to the sheets. 

Examples are the formation of diacetone alcohol from acetone [reaction type (A)] catalysed by barium or strontium hydroxide at 20—30°C [368] or by anion exchange resin at 12.5—37.5°C [387], condensation of benzaldehyde with acetophenone [type (C)] catalysed by anion exchangers at 25—-45°C [370] and condensation of furfural with nitromethane [type (D)] over the same type of catalyst [384]. The vapour phase self-condensation of acetaldehyde over sodium carbonate or acetate at 50°C [388], however, was found to be first order with respect to the reactant. 

Some novel bicyclic pyrylium salts arise when a dicarboxylic acid derivative is used. For example, although decanedioyl chloride did not diacylate isobutene, possibly because of strain inherent in the expected product, 1,12-dodecanedioyl chloride gave a very low yield of the pyrylium salt (658) (62T1079). A dilute solution of the reactants in nitromethane was used in order to favour the intramolecular reaction. In a similar vein, a macrocyclic alkene, such as cyclododecene, undergoes diacylation to the bicyclic salt (659) (68TL4643), whilst... 

To a solution of 13 g 2,5-dimethoxy-4-(n)-propylbenzaldehyde in 100 mL nitromethane, there was added 1.3 g anhydrous ammonium acetate and the mixture held at reflux for 1 h. Removal of the solvent/reactant under vacuum yielded a spontaneously crystallizing mass of orange solids that was removed with the help of a little MeOH. After filtering and air drying there was obtained 7.5 g 2,5-dimethoxy-B-nitro-4-(n)-propylstyrene with a mp of 118-122 °C. Recrystallization from CH3CN gave an analytical sample with a mp 123-124 °C. Anal. (C13Hl7N04) N. 

In their study of the decomposition of nitromethane, Rice and Thompson [94] introduced a new approach for constructing potential energy surfaces for many-atoms systems that react via multiple pathways. The basic idea of the approach is to construct potentials that accurately describe the various equilibrium regions, e.g., reactants and products, and then write the overall global potential as Vtotal=E SjV where j denotes the various stable species, the Vi are the analytical potentials for those species, and the Sj are weighting functions that effect a switching between the potentials... 

Both 2- and 3-nitrothiophenes have been synthesized by direct cyclization. While the former have been prepared with the help of type 1 reagents alone (nitromethane, bromonitromethane), the preparation of the latter has involved reagents of types 2 and 3. A synthesis in which both reactants carry nitro groups has led to 2,4-dinitrothiophenes. 

CAUTION Distillation of nitromethane and reactions using it as a solvent or a reactant at an elevated temperature, as wei as reactions of nitroaikanes in general, should be conducted behind a safety shield. In one instance a minor deflagration was observed upon erroneously aerating the distillation residue while it was still hot. The apparatus, therefore, should only be ventilated after cooling to ambient temperature, and nitrogen, not air, is recommended for this purpose. 

An example of reaction type (c) in Table 5-4 is the well-known Menschutkin reaction [30] between tertiary amines and primary haloalkanes yielding quaternary ammonium salts. Its solvent dependence was studied very thoroughly by a number of investigators [51-65, 491-496, 786-789]. For instance, the reaction of tri-n-propylamine with iodomethane at 20 °C is 120 times faster in diethyl ether, 13000 times faster in chloroform, and 110000 times faster in nitromethane than in -hexane [60]. It has been estimated that the activated complex of this Menschutkin reaction should have a dipole moment of ca. 29 10 Cm (8.7 D) [23, 64], which is much larger than the dipole moments of the reactant molecules (tris- -propylamine 2.3 10 Cm = 0.70 D iodomethane 5.5 10-3 1 64 D) [64]. 

The solvent-induced change in rate is, however, much larger than expected from the relatively small difference in polarity between nitromethane and hexamethylphos-phoric triamide. This, together with the correlation between rate decrease and increase in the solvent donor number DN cf. Table 2-3 in Section 2.2.6), suggests that specific solvation and stabilization of the diazonium ion by EPD solvents play a dominant role in the reaction (5-27). Very likely, formation of an EPD/EPA complex between the reactants in a rapid preequilibrium step precedes the rate-controlHng first step [504, 792],... 

The solvent effects on rates shown by these two reactions were determined employing the solvents chloroform, dichloromethane, acetonitrile, ethyl acetate, benzene, tetrahydrofuran and dioxane. Solvents which react with TCNE, such as nitromethane, dimethylformamide and protic solvents, as well as cyclohexane, carbon tetrachloride and tetrachloroethylene, in which the reactants have very low solubility, were deliberately excluded from the study. The observed solvent effects were virtually identical for both Diels-Alder and [2 + 2] cycloaddition processes. Statistical correlations of rate data using a multiparameter equation with dependencies based on acceptor properties, polarizability and inherent polarity of the solvents gave nearly identical coefficients through the regression analyses for each term for both reactions, and excellent linear fits to the rate data. 

Subsequently, other workers including O Neill and Cole (4 and Dannenberg (5 ) showed that Reactions 2 and 3 proceed to the exclusion of Reaction 4. The reactivity of a particular epoxide-amine system depends on the influence of the steric and electronic factors associated with each of the reactants. It has been known for some time that hydroxyls play an important role in the epoxide-amine reaction. For example, Shechter et al. ( ) studied the reaction of diethylamine with phenylglycidyl ether in concentrated solutions. They showed that acetone and benzene decreased the rate of reaction in a manner consistent with the dilution of the reactants, but that solvents such as 2-propanol, water, and nitromethane accelerated the reaction (Figure 3). They also found that addition of 1 mol of phenol to this reaction accelerated it to an even greater extent that addition of 2-propanol or water. 

The "modest" acceleration of the amine-epoxide reaction by nitromethane was ascribed to the influence of the high dielectric constant of the solvent. The greater influence of hydroxyl-containing compounds in accelerating this reaction has been suggested to result from the formation of a ternary intermediate complex of the reactants with hydroxyl-containing material, such as that proposed by Smith (6) or Mika and Tanaka (7) ... 

In general the reaction of nitroalkanes with aldehydes can be carried out by one of three processes 125 (1) Just sufficient alkali may be added to provide a sufficiently rapid reaction without dehydration or polymerization the reaction is slow and with the more complex reactants yields are also much lowered. (2) An equimolar amount of 10N-sodium hydroxide solution may be added at not more than 10°, but this method gives good yields only with nitromethane and straight-chain aldehydes and it fails with secondary nitroalkanes. (3) A solution of the aldehyde bisulfite compound may be treated with a warm solution of the sodium salt of the nitroalkane, primary nitro compounds then giving 70-80% yields. 

The development of the preparation of nitroparaffins from laboratory scale through pilot-plant to full-scale operation covered a 20-year-long effort by Commercial Solvents Corporation. A full-scale plant with a capacity of more than 10,000,000 lb per year went on stream in 1955. By a process of nitration of propane, the main production of nitroparafl5ns includes nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane. The nitration is done in the vapor phase. A flow diagram illustrating the process is shown in Fig. 4-17. There are five process sections in the nitroparaffin preparation. These involve (1) nitration, (2) products recovery, (3) products purification, (4) products separation, and (5) reactants recovery. A report by Schecter and Kaplan states that conditions for the nitration of propane are 770 F (410 C) at pressures of 115-175 psi. Initially the vapor-phase... 

Gamma irradiation with 195,000 roentgens per hour from Co source uf propane gas did nut significantly increase the yield of the nitration, except when oxygen was added to the reactants. Also the irradiation of liquid propane prior 10 the reaction increased the yield by 10—15% relative percentages. The products distribution (nitromethane, nitroethane, 1-nitropropane and 2-nitro-propane) was unaffected by radiation. 

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