2-Pyrrolidones special

The technically most important polysulfide is poly thiophenylene or poly(p-phe-nylene sulfide), PPS. It is obtained by reacting sodium sulfide and p-dichlo-robenzene in a polar solvent, for example, l-methyl-2-pyrrolidone at about 280 °C under pressure. The mechanism of the reaction is very complex and cannot be described by a simple aromatic substitution. This synthesis requires special autoclaves and is therefore not suitable for a laboratory course (for an experimental procedure see Table 2.3). 

Special procedures (44) are required for the demonstration of N-terminal pyrrolidone carboxylic acid residues in peptides and proteins frequently, pyrrolidone carboxylyl-peptides can be detected by the procedure of Rydon and Smith (SO). Discovery of enzymes capable of cleaving pyrrolidone carboxylic acid from the N-terminus of peptide chains should facilitate studies of this type (45, 46) (see below). 

Special solvent. Newman - recommends N-methyl-2-pyrrolidone as solvent for the reaction of an aryl halide with cuprous cyanide to produce the corresponding nitrile. Dimethylformamide (b.p. 153°) has been suggested as a better solvent than originally used pyridine (b.p. 115°), but l-methyl-2-pyrrolidone has an even higher boiling point and seems still more satisfactory. An example is the synthesis of... 

Rhodium chloride (0.057 mmol, Aldrich, RhClj SHjO, high purity) and polymer (2.0 mmol monomer units of polyvinyl-2-pyrrolidone or poly-2-ethyloxazoline, special grade, Aldrich) were dissolved in water (20 ml). This mixture was heated at 373 K for 2 hours. Then, it was rapidly mixed with 130 ml alcohol (methanol, ethanol, 1-propanol or 1-butanol, p.a., Merck) and heated to 348,353,373 and 393 K, respectively. Heating at that temperature was continued for 48 hours. Then, the colloidal solutions were cooled with liquid nitrogen, the solvent was evaporated under vacuum and the materials were redissolved in 1-butanol. 

Gamma-Butyrolactone (GBL) is an intermediate for the manufacture of Pyrrolidones which have a wide range of uses such as speciality solvents, functional monomers and pharmaceutical intermediates. GBL can be made by the vapour phase dehydrogenation of 1,4-butanediol over a copper/pumice catalyst at 200°C. It is also available as a by-product with THF in the Davy McKee two step butane diol process starting from maleic anhydride (MAN) via diethylmaleate [27]. 

Chemicals burns by hydrofluoric acid are the most dangerous of all injuries caused by acids and need special treatment. However, even substances thought to be less toxic, such as iSr-methyl-2-pyrrolidone, may cause acute ICD (Malten et al. 1979). 

Other monomers that have been evaluated or used to some extent to gain special properties include vinyJ acetate, ethyl acrylate, 2-ethylhexyl acrylate, 2-vinyl pyridine, n-vinyl pyrrolidone, dichlorostyrene, " and bromostyrene/ ... 

Proline represents a unique class of molecules among amino acids (Fig. 1). As pointed out by Adams, the inclusion of the a-amino group within a ring structure bestows a number of special properties (1). With its peptide bond within the pyrrolidone ring, proline confers rigidity and three-dimensional stability to proteins. The high content of proline and hy-droxyproline in collagen contributes to the unique physical properties of this structural protein. Less appreciated but perhaps equally important is... 

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