Lactams poly

Poly [2-(7V, 7V-dimethy lamino)ethy 1 methacry late-co-7V-vinylcapro lactam] Poly[2-(5,5-dimethyl-l,3-dioxan-2-yloxy)ethyl acrylate-co- 147... 

Lead sesquioxide is used as an oxidation catalyst for carbon monoxide ia exhaust gases (44,45) (see Exhaust control), as a catalyst for the preparation of lactams (46) (see Antibiotics, P-lactams), ia the manufacture of high purity diamonds (47) (see Carbon, diamond-natural), ia fireproofing compositions for poly(ethylene terephthalate) plastics (48), ia radiation detectors for x-rays and nuclear particles (49), and ia vulcanization accelerators for neoprene mbber (50). 

Anionic polymerization of lactams was shown to proceed according to what is called the activated monomer mechanism. With bischloroformates of hydroxy-terminated poly(tetramethyleneglycol) and poly(styrene glycol) as precursors for a polymeric initiator containing N-acyl lactam ends, block copolymers with n-pyrrol-idone and e-caprolactam were obtained by bulk polymerizations in vacuum at 30 and 80 °C, respectively361. ... 

Polymers are formed via two general mechanisms, namely chain or step polymerisation, originally called addition and condensation, respectively, although some polymerisations can yield polymers by both routes (see Chapter 2). For example, ring opening of cyclic compounds (e.g., cyclic lactides and lactams, cyclic siloxanes) yield polymers either with added catalyst (chain) or by hydrolysis followed by condensation (step). Many polymers are made via vinyl polymerisation, e.g., PE, PP, PVC, poly(methyl methacrylate) (PMMA). It could be argued that the ethylenic double bond is a strained cyclic system. 

Low molecular weight poly(/3-peptide)s may be synthesized in an analogous manner via the ROP of /3-amino acid-N-carboxyanhydrides.9 Longer chain materials may be prepared by the ROP of /3-lactams (Scheme 28). This polymerization is initiated by a range of metal amides, of which Sc[N(TMS)2]3 offers particularly high levels of control.997... 

Stereosequences in polymers having the general formula — CHR—X—Y— [e.g., poly-a-amino acids, polymers derived from substituted oxiranes, thi-iranes, aziridines, lactones or lactams, and 1,4 polymers of 1- (or 4) monosub-stituted butadienes] are not affected by the degeneracy phenomena existing in vinyl polymers. Their number is indicated in the first column of Table 2. 

The synthesis of polyamides follows a different route from that of polyesters. Although several different polymerization reactions are possible, polyamides are usually produced either by direct amidation of a diacid with a diamine or the self-amidation of an amino acid. The polymerization of amino acids is not as useful because of a greater tendency toward cycliza-tion (Sec. 2-5b). Ring-opening polymerization of lactams is also employed to synthesize polyamides (Chap. 7). Poly(hexamethylene adipamde) [IUPAC poly(iminohexanedioylimi-nohexane-l,6-diyl) or poly(iminoadipoyliminohexane-l,6-diyl)], also referred to as nylon 6/6, is synthesized from hexamethylene diamine and adipic acid [Zimmerman, 1988 Zimmerman and Kohan, 2001]. A stoichiometric balance of amine and carboxyl groups is readily obtained by the preliminary formation of a 1 1 ammonium salt (XU ) in aqueous solution at a concentration of 50%. The salt is often referred to as a nylon salt. Stoichiometric... 

Acetylcarbazole and 9-ethyl-3-propionylcarbazole underwent normal Wilgerodt reactions. The ketone 174 reacted with sodium azide-poly-phosphoric acid with migration of the alkyl substituent generating lactam 203. ... 

Method of preparing random poly(amide-fe-ester) derivatives through depoly merization/repolymerization of cyclic polyesters then coreacting with lactam derivatives using a nonmetallic carbene catalyst This method for preparing polyester amides is unreported. 

The NCA 138 represents the amino-protected and carboxy-activated form of poly-oxamic acid 140, the hydroxylic amino acid portion of the antifungal family of polyoxins 139, Fig. 8. Other polyolic NCAs such as 141,142, and 143, Fig. 9, have also been prepared from the corresponding a-hydroxy p-lactams with equal success [123, 124]. 

The development of efficient routes to synthesize (3-lactams is an area of significant research interest [41 -5]. This has been driven, in large part, by the importance of these molecules as constituents of antibiotics, ranging from penicillin-based substrates to a number of more recently developed compounds (e.g., penems, cephems, monobactams, carbapenems, and trinems) [46-51]. (3-Lactams have also been demonstrated to be important synthons in organic synthesis (Fig. 1) [52,53] and to be monomers in the generation of polyamides [e.g., poly((3-peptides)] [54, 55]. 

Although the polymerization of e-caprolactam was described above, there is no difference in principle from the process flow sheets for centrifugal molding of items from other polymers and oligomers. Nevertheless, in most cases, the high temperatures used in lactam polymerization are not required, and the flow sheet as a whole is simplified. In industrial practice, poly(methyl methacrylate) pipes,172 and sheets of polyurethanes and unsaturated polyesters are obtained by centrifugal casting. 

Janssen et al. [144] focused their work on ozonization of polyvinyl lactam, grafting with hydrophilic methacrylic monomers for applications in the field of contact lenses and other products used in the medical domain. The most studied polymer remains the poly-N-vinyl pyrrolidone which is ozonized either in solid state or in aqueous solution. This activation step leads to three hydroperoxides per chain but also to chain scissions. The resulting product is formulated with different mixtures of methacrylic and dimethacrylic monomers to graft them onto activated polymer by UV initiation. Using dimethacrylic monomers lead to perfect cross-linked polymers presenting excellent resistance to solvents. Unfortunately, the mechanisms of action of ozone onto polyvinyl lactams do not seem to have been studied in detail. 

It has been noted58 that, although the precise structure of dithyminylmercury (as well as that of other mercuri derivatives of pyrimidines, to be described later) is not known, the possibility of lactim-lactam tautomerism exists in this molecule. Aside from considerations of reaction mechanisms, the mercuri condensation is far more rapid (usually requiring 0.5 to one hour duration) than the Hilbert-Johnson reaction, which requires days to run its course. This factor is probably of importance where (a) the purity of acylohalogeno sugars is questionable (as is often the case with sirupy poly-O-acylglycofuranosyl halides, in which may be present some traces of mineral acid), and (b) the stability of the halide at elevated temperatures is likely to be of a low order. 

As beta-lactam antibiotics continue to be a major contributor to human health preservation, research on the biosynthesis of penicillin, an almost ancient drug, continues to open up roads to new technologies and perspectives. The provision of precursor peptides to be transformed enzymatically with chemically unachieved efficiency into mono- or bicyclic antibiotics has been termed by Jack Baldwin and colleagues the irreversible commitment of metabolic carbon to the secondary metabolism [1]. The synthesis of such peptides is indeed performed by a remarkable class of synthetases which, in contrast to the protein-synthesizing machinery, have been termed a nonribosomal system or nonribosomal peptide synthetases (NRPS) [2]. These peptide synthetases have been shown to catalyze the irreversible synthesis of peptides differing both in sequence and stmctural variability, thus extending the scope of directly gene-encoded poly-... 

J. W. Kelly and J. T. Stewart, Separation of selected beta lactam antibiotic epimers on gamma cyclodextim ion exchange ethylvinyl benzene divinylbenzene copolymer and poly(styrene-divinyl benzene) copolymer stationary phases, J. Liquid Chromatogr., 14 2235(1991). 

In conclusion, the results of our study indicate that the principal features of the formation of poly (2,6-dioxo-l,4-piperidinediyl) trimethylene by thermal polymerization of / -carboxymethyl caprolactam consists in an initial isomerization of the caprolactam derivative to a reactive species and subsequent polymerization of the latter by condensation. The reactive intermediate is in all probability either or both the 3-(3-aminopropyl)-glutaranhydride or its linear dimer. Both the conversion of the lactam by isomerization and the polycondensation follow second-order kinetics. 

Aliphatic poly(disulfides) A, Aliphatic poly (carbonates) , Aliphatic poly(anhydrides) , Aliphatic poly (di-esters) , Aliphatic poly(sulphones) O, Poly(terephthaIates). (B) , Aliphatic poly(lactams) O, Aliphatic poly (di-amides) , Aliphatic poly(di-urethanes) A, Aliphatic poly(di-urea) , Aliphatic poly(terephthala-mides) , Polyfxylylene diamides) and Polyfphenylene diethylene diamides). 

The Ym vs. Nch2 curves belong to two types, similar but different. The first type, Fig. 6.7a, is identical in curvature for all polymer families containing only one functional group per repeating unit poly-oxides, -sulphides, -carbonates, -lactams, -lactones and -sulphones belong to this type. 

Cyclooctadiene (COD) is an intermediate for the manufacture of poly-octenamers, while 1,5,9-cyclododecatriene (CDT) is the starting material for the manufacture of dodecanoic acid and lauryl lactam. The latter is converted to the polyamide fiber Vestamide (DuPont). Both COD and CDT are made from butadiene (Equations 21 and 22). 

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