Subject 1 -methyl-2-pyrrolidone

Aldehyde linearity is high (ca. 90%). Sufficient N-methyl-pyrrolidone (NMP ca. 40%w) and some water (1 -2%w) are applied to achieve a one-phase system in the reactors. After reaction, water is added in a mixer (phase ratio 1 1 v/v), followed by efficient phase separation in a settler, with virtually all catalyst in the NMP/water layer. The crude product layer is subjected to a multi-stage water extraction to remove residual NMP and catalyst, and a final treatment over a silica-bed to reduce Rh leach levels from 0.2 ppmw to 0.02 ppmw. The recycle catalyst layer (in NMP/water) is dried in two steps, to evaporate water and achieve the low water concentrations required for one-phase reaction, and then recycled to the reactors. Water is recycled, from evaporators, via water extraction, to the mixer. The flexibility of this process with respect to alkene carbon number seems excellent good performance has been found for Cs-C aUcenes [61]. 

Butadiyne, H-CSC-C C-H, as a polymerizable monomer, has received very little attention from polymer chemists although its discovery dates back to Bayer in 1885. This structurally simple, highly reactive bifunctional molecule would be expected to have been a monomer of considerable interest in the field of polymer chemistry. Possibly, limited butadiyne stability may account for the small amount of polymerization research. The The compound is a liquified gas at room temperature (BP = 10 C), discolors slowly in sealed vessels at 20 C and may explode if heated. Storage and instability problems may be circumvented. Prevention of explosion may e accomplished by addition of an inert diluent such as butane. The monomer may also be stored in t e form of a labile complex with N-methyl-pyrrolidone. Its thermal condensation or polymerization was briefly recorded as an observation by Bayer and described in a little more detail by Miiller in 1925. Prevention of this thermal polymerization has been the subject of several patents with methylene blue, pyridine and vinylpyridine claimed as inhibitors. 

The reaction gas is cooled to ambient temperature in a water spray column, and the quench water that condenses is fed back in a closed cycle to the electric arc reactor. The gas is then compressed and subjected to a sequence of scrubbing operations with selective solvents [i.e., methanol, octane, and A/ -methyl-2-pyrrolidone (NMP) in that order]. The solvents are regenerated by low-pressure stripping with gas fractions from the production process. This removes mainly the polyunsaturated hydrocarbons. 

Size exclusion chromatography (SEC) is a powerful method for determining molecular weight distributions of mixtures. Because coal fractions usually contain both polar and nonpolar molecules, interpretation of SEC data is difficult and subject to error. Advantages and problems with tetrahy-drofuran (THE), A(-methyl-2-pyrrolidone, and pyridine have been observed (Lafleur and Nakagawa, 1989) but some investigators continue to employ these solvents, thereby ignoring any pitfalls. 

Wholly aromatic Pis like Kapton, insoluble in common organic solvents, are usually synthesized through a two-step method PI precursors, high molecular weight poly(amic acid)s (PAAs) are readily synthesized from ring-opening polyaddition of an extra-pure dianhydride and an equimolar diamine in aprotic amide solvents such as A,A-dimethylacetamide (DMAc) and A-methyl-2-pyrrolidone (NMP), then the as-cast dried PAA films are subjected to thermal or chemical imidization. The reaction scheme and the abbreviations of polymers and monomers are shown in Fig. 1. 

Perhaps the biggest impact will be over the use of solvents since many of the more common organic solvents are under threat from REACH these include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF) and dime-thylacetamide (DMAc). (For more information on solvent substitution guides see Chapter 2, Tools for Facilitating more Sustainable Medicinal Chemistiy , by Helen Sneddon and James Sherwood s Chapter 3 on renewable solvent selection.) The electronics industry has also been subject to chemical legislation that aims to replace especially hazardous substances. RoHS (restriction on hazardous substances) targets certain chemicals, including lead, mercuiy, cadmium chromates and polybrominated flame retardants. ... 

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