The Kinetics of the Persulfate Oxidation of 2-Propanol in the Presence of Other Organic Compounds

Frost and Chilling Injury to Growing Plants

“…Since changes in the steric conformation of proteins may be affected by freezing and thawing (Levitt, 1966a), it follows that these groups may also be involved in the physiological processes that accompany the changes in water activity (Tappel, 1966). Measurements of the SH and SS contents of plants before and after freezing have indicated a conversion of protein SH and SS when the freezing resulted in killing, but not when the plants survived uninjured (Levitt, 1962). Similar results were obtained with injury by heating.…”

“…Less than 3 a The value of hydrophobic bonding energy is a function of the nonpolar groups involved and also temperature, decreasing with a reduction in temperature (Nemethy and Scheraga, 1962b). Other data are from Levitt (1962Copyright © 1962 Academic Press, New York).…”

“…Plants incapable of hardening at low temperatures also showed a marked increase in SH at hardening temperatures, but only if permitted to wilt (Levitt et al, 1961). Levitt (1962) therefore proposed a hypothesis which assumes that ice forms extracellularly when a plant is frozen and the water that separates the protoplasmic proteins moves to these extracellular ice loci, thus causing the cell to dehydrate. At a certain degree of dehydration, which varies with the plant resistance to freezing injury, the SH and SS groups of adjacent protein molecules would approach one another closely enough to permit chemical reactions to occur (see Levitt, 1962).…”

“…Levitt (1962) therefore proposed a hypothesis which assumes that ice forms extracellularly when a plant is frozen and the water that separates the protoplasmic proteins moves to these extracellular ice loci, thus causing the cell to dehydrate. At a certain degree of dehydration, which varies with the plant resistance to freezing injury, the SH and SS groups of adjacent protein molecules would approach one another closely enough to permit chemical reactions to occur (see Levitt, 1962). The reaction could be of two kinds: an oxidation of two SH groups to SS, or an SH (=> SS interchange reaction.…”

The mechanism of the oxidation of alcohols and aldehydes with peroxydisulphate ion

“…The order of the reaction for peroxydisulphate also changes from 1 to 3/2 when its initial concentration increases for all the cases investigated.z2 So we have to deal with a similar phenomenon which does not depend on the nature of the alcohol. At low initial alcohol concentrations we have equations (14) and at high initial concentrations, when the concentration of alcohol is 'limiting', (15). Some kinetic parameters are in Table 1.…”