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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 4 (1991), S. 399-403 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the elimination of several polar 2-substituted ethyl methanesulphonates in the gas phase were determined in a static system, seasoned with allylbromide, and in the presence of at least equal amount of the freeradical suppressor propene and/toluene. The working temperature and pressure ranges were 290-360°C and 31°199 Torr (1 Torr = 133.3 Pa), respectively. The reactions are homogeneous, unimolecular, show a first-order rate law and take place according to the following equations: for 3-chloropropyl methanesulphonate, log k1 (s-1) = (12.01 ± 0.18) - (171.7 ± 2.1) kJ mol-1 (2.303RT)-1; for 4-chlorobutyl methanesulphonate, log k1 (S-1) = (11.78 ± 0.31) - (166.1 ± 3.5) kJ mol-1 (2.303RT)-1; for 3-methoxypropyl methanesulphonate, log k1 (s-1) = (11.50 ± 0.36) - (163.3 ± 4.0) kJ Mol-1 (2.303RT)-1; and for 2-ethoxyethyl methanesulphonate, log k1 (s-1) = (11.52 ± 0.37) - (167.3 ± 4.1) kJ mol-1 (2.303RT)-1. The present data together with those reported in the literature show that alkyl 2-substituted ethyl methanesulphonates give an approximate straight line when log k/ko vs σ* values (ρ* = -0.82 ± 0.088, intercept = 0.0084 ± 0.0209 and correlation coefficient r = 0.967 at 320°C) are plotted. However, polar substituents at the 2-position of ethyl methanesulphonates give rise to an inflection point at σ*(CH3) = 0.00 into another very good straight line (σ* = -0.29 ± 0.013, intercept = -0.0065 ± 0.0213 and r = 0.994 at 320°C). The mechanism of these reactions is considered to be heterolytic in nature, proceeding in terms of an intimate ion-pair intermediate.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the gas-phase elimination of two 2-haloethyl methanesulphonates were determined in a static system over the temperature range 310-380°C and pressure range 26-174 Torr. The reactions in seasoned vessels, with the free-radical inhibitor propene and/or toluene always present, are homogeneous and unimolecular, and follow a first-order rate law. The rate coefficients are given by the Arrhenius equations: for 2-bromoethyl methanesulphonate log k1 (s-1) = (11·70 ± 0·43)-(172·8 ± 4·8) kJ mol-1 (2·303RT)-1 and for 2-chloroethyl methanesulphonate log k1 (s-1) = (11·67 ± 0·50)-(173·9 ± 6·0) kJ mol-1 (2·303RT)-1. The bromo compound was found to be more reactive than the chloro compound. At 340°C, for Br k1 = 9·46 × 10-4 s-1 and for Cl k1 = 7·12 × 10-4 s-1. Apparently, electronic factors seem to be operating in these elimination reactions.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2017-06-24
    Description: Peat is the most widely used substrate component and extensively used in greenhouse cultivation, landfill cover soils, urban parks and gardens, urban agriculture or green roofs, due to its excellent combination of physicochemical properties. The production of hydrochar by hydrothermal carbonization (a process at lower temperatures than pyrolysis and using wet conditions) could industrially reproduce the initial conditions of biomass humification and lead to materials with similar properties to those of peat. The objective of this work was to compare peat (PT, Control), a hydrochar prepared from biosolids (HSL), a hydrochar prepared from the organic fraction of urban wastes (HUW) and two mixtures (PT+HSL and PT+HUW) at a 50 % volume rate for their potential use as substrates with multiple applications. Ryegrass was established at a rate of 40 g seeds cm -2 in the potting mixtures. Hydrophysical and biochemical properties (microbial biomass and the enzymes dehydrogenase, β-glucosidase and phosphomonoesterase) were analyzed for PT, HSL, HUV and their combination (PT+HSL and PT+HUW). Treatments with biosolids hydrochar increased ryegrass production by 184% (HSL) and by 216% (PT+HSL) dry weight compared to the control (peat). Biochemical properties depended strongly on hydrochar type, while the hydrophysical properties of the hydrochars were similar to those of peat. Overall, our results found hydrochar-peat mixtures (PT+HSL and PT+HUW) to be suitable for the preparation of growing media.
    Print ISSN: 1085-3278
    Electronic ISSN: 1099-145X
    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley-Blackwell
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