| Range |
12 - 28 kcal/˚/mole
|
| Organism |
Mammals |
| Reference |
Robbins, Clarence R. Reducing human hair, pp.69-101, chapter 3 in the book Chemical and physical behavior of human hair / Clarence R. Robbins.-2nd ed (2002) p.75 3rd paragraph |
| Primary Source |
[6] R. Randall Wickett, Kinetic studies of hair reduction using a single fiber technique, j. Soc. Cosmet. Chem., 34, 301-316 (September/October 1983) [18] Hans‐Dietrich Weigmann, Reduction of disulfide bonds in keratin with 1,4‐dithiothreitol. I. Kinetic investigation, Polymer Sci. A-I:6. 2237 (1968) link [20] KW Herrmann, Hair keratin reaction, penetration, and swelling in mercaptan solutions, Transactions of the Faraday Society, p.1663-1671, 1963 link |
| Method |
Primary [6] synopsis: "A technique for investigating reduction kinetics of hair using single hair fibers is described. The method is based on stress relaxation caused by disulfide bond breakage, and can be used for fundamental studies of parameters affecting hair reduction rates." Primary source [18] abstract: "The kinetics of the reduction of disulfide groups in wool fibers with dithiothreitol has been investigated." Primary source [20] abstract: "The rate-limiting step in the heterogeneous reaction between the disulphide cross-links of hair keratin and alkaline mercaptan solutions was found to be diffusion of the mercaptan species through the fibre." |
| Comments |
P.75 3rd paragraph: "The activation energy for the reduction of either human hair or wool fiber at alkaline pH is of the order of 12 to 28 kcal per degree mole [primary sources]. Wickett [primary source 6] explains that when the mechanism is diffusion-rate-controlled, the activation energy is higher (28.0 kcal per degree mole) [primary source 6], because the boundary movement depends on both reaction and diffusion. However, when the rate depends only on the chemical reaction, the activation energy is lower (19.7 kcal per degree mole)." Primary source [20] abstract: "Pseudo second‐order kinetics, second‐order with respect to the concentration of the disulfide groups in keratin, has been found to describe the experimental data at pH 3.50. An activation energy of 25 kcal/mole has been determined for the rate‐controlling step at that pH value, as opposed to an activation energy of 13.4 kcal/mole for the diffusion‐controlled process at neutral pH." |
| Entered by |
Uri M |
| ID |
116980 |