ABSTRACT
The mechanism of diphosphate formation from (R)-2-chloro-2-oxo-5,5-dimethyl-4-(R)-phenyl-1,3,2-dioxaphosphorinane (5a) and 2-hydroxy-2-oxo-5,5-dimethyl-4-(R)-phenyl-1,3,2-dioxaphosphorinane (6) has been investigated. The products formed are the ax-ax diphosphate 7a and the ax-eq diphosphate 7b, with no evidence in the 31P NMR spectrum for pentacoordinate chlorooxyanionic phosphoranes 9. The structure of 7bhas been established unambiguously by NMR spectroscopy, mass spectrometry, and elemental analysis, and the structures of 5a and 7a have been confirmed by X-ray crystallography. The mechanism of the crucial diphosphate-forming reaction has been probed using 18O-labeling studies. The 18O-labeling patterns are consistent with the unsymmetric ax-eq diphosphate 7b arising from selective nucleophilic attack of the axial oxygen of 6 on the chloride 5a with inversion of configuration at phosphorus. The symmetric ax-ax diphosphate 7a can be formed directly, as a result of selective nucleophilic attack of the axial oxygen of 6 on the chloride 5a with retention of configuration, but the majority arises indirectly by isomerization of the ax-eq diphosphate 7b. The isomerization apparently involves intermolecular exchange, with nucleophilic attack of the phosphate anion 6 on the equatorially substituted phosphorus atom of 7b with inversion of configuration at phosphorus.
Subject(s)
Heterocyclic Compounds, 1-Ring/chemistry , Heterocyclic Compounds, 2-Ring/chemical synthesis , Organophosphates/chemical synthesis , Crystallization , Crystallography, X-Ray , Indicators and Reagents , Magnetic Resonance Spectroscopy , Mass Spectrometry , Models, Molecular , Oxygen/chemistryABSTRACT
The known beta-phenethylamine ( 1) and the new alkaloid 2-beta-methyl-3-beta-hydroxy-6-beta-piperidinedodecanol ( 2) were isolated from the aerial parts of PROSOPIS ALBA. Both compounds showed DNA binding effects of 27 and 50%, respectively, at 0.50 mg/ml.
ABSTRACT
A population-based study of chemical eye injury in the chemical industry is reported. In a population of 62,839 workers studied for one month (approximately 10 million man-hours), 60 eye injuries (45.1 per cent of all eye injuries) were caused by chemicals (eye injury incidence 11.4 per 1000 employees per year). Six patients (10 per cent) required hospital attention. No sight-threatening injuries occurred. Health workers within the industry have recognized that most of these injuries are avoidable. Eye protectors were not a requirement in some situations where injury occurred (one-third of injuries), were not used where specified in some cases, and in others failed to prevent injury even when worn. This low incidence of injury can be reduced further by appropriate selection and wear of protectors, by education and by legislation.
Subject(s)
Chemical Industry , Eye Injuries/chemically induced , Eye Protective Devices , Occupational Diseases/chemically induced , Eye Injuries/epidemiology , Humans , Occupational Diseases/epidemiologySubject(s)
Cataract Extraction , Corneal Transplantation , Lenses, Intraocular , Aged , Female , Graft Survival , Humans , Male , Treatment Outcome , Visual AcuityABSTRACT
A population of 63,000 chemical industry workers was studied prospectively over approximately 10,000,000 man-hours of work. A total of 133 eye injuries were reported (8.4% of all injuries), of which 22% needed medical attention. Eye protection was often not worn, some protectors may have been wrongly recommended for a particular task, and some protectors may have failed to perform adequately. In this population, an eye injury occurred once every 75,000 man-hours of work on average (injury incidence 23:1000:year). Most injuries were avoidable. Revision of protection protocols at work, and improved education of personnel are needed to reduce the incidence of occupational eye injury.
