Oxime structure

Other double-bond moieties which are often encountered include the imines and oximes (Structure 5.4). 

Fig. 21 Bond-angle changes at the migration origin in four oxime structures [105] (see text) as a function of the lengthening of the N-OX bond. Reprinted with permission from Edwards et al. (1987).

Pyrrolidone is a lactone used for the production of nylon-4. This reactant may be produced by the reduction ammoniation of maleic anhydride. s-Caprolactam, used in the production of nylon-6, may be produced by the Beckman rearrangement of cyclohexanone oxime (structure 17.11). The oxime may be produced by the catalytic hydrogenation of nitrobenzene, the photolytic nitrosylation of cyclohexane (structure 17.9), or the reaction of cyclohexanone and hydroxylamine (structure 17.10). Nearly one-half of the production of caprolactam is derived from phenol. 

When the nucleophile is already present as a part of the starting oxime (for example, a heteroatom or a C=C double bond), intramolecular trapping of the electrophilic intermediate is possible and a new cycle is formed. This transformation is usually referred to as a Beckmann Rearrangement-Cychzation reaction. Two modes of ring closure may be possible, depending on the oxime structure (equations 111 and 112) ... 

It was observed that a-amino oximes 511, when treated with sodium borohydride in boiling acetonitrile, produced the expected fragmentation products 513 in moderate to good yields (31-87%) (equation 225). The use of the hydride-induced fragmentation in cyclic oximes leads to amino nitrile compounds, as a result of the reduction of the immonium salt intermediates 512. Careful selected oxime structures showed that the reaction time increases when the stabihty of the immonium intermediate decreases, showing the importance of the mesomeric assistance. 

Another possibility to treat a poisoning with esterase inhibitors of the organophosphorous type are the so called esterase reactivators compounds with an oxime structure like obidoxime and prali-doxime. The oxime moiety has a very high affinity for the phosphorous atom and can thereby under certain circumstances hydrolyze the otherwise stable organophosphorous-enzyme complex. 

O-tnethyl oxime and 252A a hydroxy O-methyl oxime, as shown in Fig. 19. The configuration of the 0-methyloxime is not rigorously established, but it appears to be as shown for 236 and 252A (/5i). Reduction of 236 with sodium in butanol afforded a primary amine, consonant with the oxime structure of 236 (/5i). Reduction of synthetic nitropolyzonamine (see below) yields the same primary amine (K. Hutchinson, H. M. Gar-raffo, T. F. Spande, and J. W. Daly, unpublished). 

Catalysis by N-arylsulfilimines (e.g., TP-N = SMe2) and 3-picoline. Hydroxylamine or tautomeric oxime structure. 

One brief report concerns the isolation, and characterization by i.r. spectroscopy and X-ray analysis, of a most unusual metabolite from the microorganism Gymnodinium breve (responsible for the red tide effect), and which has been shown to possess the E,E) form of the oxime structure (1). ... 

Azepan-2-one (hexano-6-lactam, --caprolactam, 28) is industrially the most important azepine derivative. It is used in the production of perlon and is synthesized by Beckmann rearrangement of cyclohexanone oxime. Structurally related to caprolactam is the CNS stimulant pentetrazole 29 (1,5-pentamethylenetetrazole, see p 217). 

Hindered amine light stabilizers (HALS) were developed as photostabilizers and/or metal deactivators. It was soon determined that the oxime structure functioned as an AO as well. In fact, these AOs are almost self-regenerating so they last for long times. They also serve their original functions, thus they often do double and even triple duty. These additives are responsible for high performance PP used... 

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