The automobile exhausts are one of the major sources of particulate matter in urban areas and these particles are known to influence the atmospheric chemistry in a variety of ways. Because of this, the oxidation of dissolved sulfur dioxide by oxygen was studied in aqueous suspensions of particulates, obtained by scraping the particles deposited inside a diesel truck exhaust pipe (DEP). A variation in pH showed the rate to increase with increase in pH from 5.22 to about ∼6.3 and to decrease thereafter becoming very slow at pH = 8.2. In acetate-buffered medium, the reaction rate was higher than the rate in unbuffered medium at the same pH. Further, the rate was found to be higher in suspension than in the leachate under otherwise identical conditions. And, the reaction rate in the blank reaction was the slowest. This appears to be due to catalysis by leached metal ions in leachate and due to catalysis by leached metal ions and particulate surface both in suspensions. The kinetics of dissolved SO2 oxidation in acetate-buffered medium as well as in unbuffered medium at pH = 5.22 were defined by rate law: k obs  = k 0 + k cat [DEP], where k obs and k 0 are observed rate constants in the presence and the absence of DEP and k cat is the rate constant for DEP-catalyzed pathway. At pH = 8.2, the reaction rate was strongly inhibited by DEP in buffered and unbuffered media. Results suggest that the DEP would have an inhibiting effect in those areas where rainwater pH is 7 or more. These results at high pH are of particular significance to the Indian subcontinent, because of high rainwater pH. Conversely, it indicates the DEP to retard the oxidation of dissolved SO2 and control rainwater acidification.

Summary. 2-Diphenylphosphinato-l,3,2-dioxaborolanes and -borinanes of the type OGOI3OP(O)Ph 2 (where G =-CH2CHMe-, CH2CH2CH2-,-CH2CH2CHMe-,-CMe2CMe2-,-CMe2CH2CHMe-, -CH2CMezCH2-, -CH2CEt2CH2-, and -C6H4-) are obtained by the reaction of diphenylphosphinic acid with the corresponding 2,2'-oxo-bis-l,3,2-dioxaborolanes and -borinanes. The products are white crystalline solids, which have sharp melting points and are hydrolytically stable. They have been characterized by elemental analysis, IR and multinuctear NMR (1 ~ B, 3, p, and t ~ 9Sn) studies. The data suggest structures with monodentate phosphinato moieties and 3-coordinated boron atoms.Keywords. Boron; Diphenylphosphinato; IR; NMR; B-1 t; P-31; Sn-119. Synthesen und spektroskopische Untersuchungen yon Diphenylphosphinatoderivaten von BorZusammenfassung. 2-Diphenylphosphinato-l,3,2-dioxaborolane und -borinane des Typs OGOPOP(O)Ph 2 (mit G = CH2CHMe, CH2CHgCH2-, CH2CH2CHMe-,-CMe2CMe2-, J -CMe2CH2CHMe , CH2CMe2CH 2 , CH2CEteCH 2-und C6H4) erh/ilt man durch Reaktion von Diphenylphosphins~iure mit den entsprechenden 2,2 3, Die Produkte sind weiBe, kristalline, hydrolyseunempfindliche Festk6rper. Sie wurden mittels Elementaranalyse, IR-Spektroskopie und multinuklearer NMR-Spektroskopie (11 B, 31 p und 119Sn) charakterisiert. Die Resultate legen Strukturen mit monodentaten Phosphinatoeinheiten und dreifach koordinierten Boratomen nahe.

No abstract