N-Methylpyrrolidone and

Materials of these types have T s of some 290-300°C and some grades are claimed to be stable to about 400°C. Whilst resistant to hydrocarbons, halogenated hydrocarbons, ethers and acids the polymers are soluble in such materials as dimethylformamide, N-methylpyrrolidone and pyridine. Bases can cause stress cracking. These non-crystalline polymers are tough at temperatures as low as -46°C whilst at 260°C they have the strength shown by PTFE at room temperature. The polymers also exhibit excellent electrical insulation properties. 

Fully aromatic polyamides are synthesized by interfacial polycondensation of diamines and dicarboxylic acid dichlorides or by solution condensation at low temperature. For the synthesis of poly(p-benzamide)s the low-temperature polycondensation of 4-aminobenzoyl chloride hydrochloride is applicable in a mixture of N-methylpyrrolidone and calcium chloride as solvent. The rate of the reaction and molecular weight are influenced by many factors, like the purity of monomers and solvents, the mode of monomer addition, temperature, stirring velocity, and chain terminators. Also, the type and amount of the neutralization agents which react with the hydrochloric acid from the condensation reaction, play an important role. Suitable are, e.g., calcium hydroxide or calcium oxide. 

Figure 4. IR spectra of 1 1 N-methylpyrrolidone and pyridine mixture (1) and after exposure the mixture to NO2 (2).

Protection of carboxyl groups. Phenacyl esters can be cleaved in 90% yield with Zn-HOAc/DMI. For peptides that are poorly soluble in DMF, cleavage can be effected with Zn-anthranilic acid-pyridine in a mixture of N-methylpyrrolidone and DM.SO (86-92% yield). 

Both siloxane-polyimide copolymers and BPADA-derived copolymers exhibited excellent solubility in a variety of dipolar aprotic solvents, including tetrahydrofuran, n-methylpyrrolidone, and dimethyl sulfoxide, as well as chlorinated hydrocarbons such as o-dichlorobenzene and methylene chloride. The polymers and copolymers were typical thermoplastics exhibiting little elongation at failure. The tensile properties are summarized in Table II. 

Campbell H. L. and B. A. Striebig Evaluation of N-Methylpyrrolidone and its oxidation products toxicity utilizing the Microtox assay, Environ. Sci. Technoi, 33 (1999) 11, 1926-1930. 

Formamide derivatives can sometimes be replaced with other amides, and examples include N,N-di-methylacetamide (DMA), N-methylpyrrolidone and N V-dimethylbenzamide. The resulting chloromethyleneiminium salts react with suitable nucleophiles yielding iminium salts, but self-condensation reactions are frequently encountered when proton loss from the iminium salt can occur. This is illustrated in Scheme 2 for DMA. 

Extractive distillation processes are all based on the same operating principle, already examined in connection with the extraction of butadiene from a C4 cut The only notable differences are of a technological nature, related to the type of solvent employed. Hence commercial installations use solvent weight ratios of 5 to 6, in the presence of a polymerization inhibitor, and of 5 to 10 per cent water in the case of acetonitrile and N-merbylpyrtnlidone, enhancing the selectivity of the operation, and in anhydrous medium, in the presence of dimethylfonnamide, in view of its tendency to hydrolyse more easily to formic add and dimethylamineL Moreover, N-methylpyrrolidone and dimethyiforma-mide, unlike acetonitrile, do not lead to the formation of azeotropes with the hydrocarbons treated. 

Saturated and partially unsaturated heterocycles are widely distributed as natural products. Some are used as solvents for organic reactions, notably tetrahydrofuran (THF) and dioxan, where diethyl ether is unsuitable. N-Methylpyrrolidone and sulfolane are useful dipolar aprotic solvents, with characteristics like those of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). 

Polyvinylidene fluoride is used extensively in the electronics industry because of its piezoelectric and pyroelectric properties. Only two room temperature solvents, n-methylpyrrolidone and dimethyl acetamide, have been found. Still-wagon (37) used n-methylpyrrolidone as the solvent for low-angle laser light-scattering measurement because of the larger refractive index increment value (dn/dc) in that solvent. No SEC work in these solvents was mentioned. 

A stirred mixture of 2-benzyl-4,4-dimethyl-2-oxazoline, 2,4-dichlorobenzaldehyde, and some NaHS04 as catalyst refluxed 1.25 hrs. in N-methylpyrrolidone and xylene at 177-218° under a water separator, and refluxing continued an additional 15 min. near 218° 7-chloro-3-phenylcarbostyril. Y 84%. F. e. s. H. L. Wehr-meister, J. Heterocyclic Chem. 13, 61 (1976). 

Much information on the process to prepare PPS from 1,4-dichlorobenzene and sodium sulfide is proprietary and the process is not as easy as it looks. Sodium sulfide hydrate or a mixture of aqueous sodium hydrosulfide and sodium hydroxide is dissolved in a polar organic solvent such as N-methylpyrrolidone and the system dehydrated. Then 1,4-dichlorobenzene is added and the system held at 200 to 300 C until pol)niierization is complete, usually within ten hours. Two moles of sodium chloride are formed for every mole of PPS, and the weight of sodium chloride formed is greater than the theoretical yield of... 

Blanco, B. Beltran, S. Cabezas, J. L. Coca, J. Phase equilibria of binary systems formed by hydrocarbons from petroleum fractions and the solvents N-methylpyrrolidone and N,N-dimethylformamide. 1. Isobaric vapor-liquid equilibria J. Chem. Eng. Data 1997,42, 938-942... 

According to above principles, the nature of solvents and Solvent Handbook, this articl selected five representative solvents sulfolane, glycerol, dioctyl phthalate, N-methylpyrrolidone and N, N-dimethylformamide. The physical properties of five solvents were shown in Table 1. 

Dimethyl sulfoxide (DMSO) and A/,N-dimethylformamide (DMF), as Table 1.3 shows, are particularly effective in enhancing the reactivity of enolate ions. Both of these compounds belong to the polar aprotic class of solvents. Other members of this class that are used as solvents in reactions between carbanions and alkyl halides include N-methylpyrrolidone and hexamethylphosphoric triamide (HMPA). Polar aprotic solvents, as their name implies, are materials which have high dielectric constants but which lack hydroxyl groups or similar hydrogen-bonding functionalities. 

A Hoechst process hydrolyzes 2-perfluoroalkylethyl iodides in N-methylpyrrolidone and water by heating at 150°C for 13 h [82]. An Asahi process... 

Ovenall and Uschold [80] examined samples of PVF by F-NMR at 376.5 MHz and proton NMR at 400 MHz as solutions in N-methylpyrrolidone and as swollen gels in dimethyl-tfg sulfoxide (me2 50-df). Weak peaks in the fluorine-NMR spectra have been assigned to CH2CH2F end groups and to tertiary fluorine atoms at branch points. A differential decoupling experiment, in which the proton spectrnm was observed with... 

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