99-84-3Relevant articles and documents
Catalytic activity of the VIII group metals in the hydrogenation and isomerization of α- And β-pinenes
Deliy,Simakova
body text, p. 2056 - 2064 (2010/05/02)
The kinetic regularities of the liquid-phase hydrogenation and isomerization of α- and β-pinenes over the Pd/C, Ru/C, Rh/C, Pt/C, and Ir/C catalysts were studied at temperatures ranging from 20 to 100 °C and at hydrogen pressures of 1-11 bar using n-octane as the solvent. The hydrogenation and isomerization of α- and β-pinenes occur simultaneously on the Ru/C, Rh/C, Pt/C, and Ir/C catalysts, and the reaction mixture contains the products of double bond hydrogenation, viz., cis- and trans-pinanes. The Ru, Rh, and Pd metals have a higher catalytic activity in β-pinene isomerization than Ir and Pt. Among the VIII Group metals studied, the Pd-based catalyst has the highest catalytic activity in double bond isomerization of α- and β-pinenes. The general scheme of the mechanism of hydrogenation and isomerization of α- and β-pinenes on the Pd/C catalyst was proposed.
Conjugated dienes as prohaptens in contact allergy: In vivo and in vitro studies of structure-activity relationships, sensitizing capacity, and metabolic activation
Bergstroem, Moa Andresen,Luthman, Kristina,Nilsson, J. Lars G.,Karlberg, Ann-Therese
, p. 760 - 769 (2007/10/03)
There is a great interest in developing in vitro/in silico methods for the prediction of contact allergenic activity. However, many proposed methods do not take the activation of prohaptens to sensitizers by skin metabolism into account. As a consequence, consumer products containing potent sensitizers could be marketed. To identify prohaptens, studies regarding their structure-activity relationships and the mechanisms of their activation must be conducted. In the present investigation, we have studied the structure-activity relationships for alkene prohaptens. A series of seven alkenes (1-7), all of the same basic structure but with variation in the number and position(s) of the double bond(s), were designed and screened for sensitizing capacity using the murine local lymph node assay. Compounds 1-7 were also incubated with liver microsomes in the presence of glutathione to trap and identify reactive metabolites. The metabolic conversion of three alkenes (9-11) to epoxides (12-15) was also studied along with comparison of their sensitizing capacity. Our results show that conjugated dienes in or in conjunction with a six-membered ring are prohaptens that can be metabolically activated to epoxides and conjugated with GSH. Related alkenes containing isolated double bonds and an acyclic conjugated diene were shown to be weak or nonsensitizers. For the first time, the naturally occurring monoterpenes α-phellandrene, β-phellandrene, and α-terpinene were demonstrated to be prohaptens able to induce contact allergy. The difference in sensitizing capacity of conjugated dienes as compared to alkenes with isolated double bonds was found to be due to the high reactivity and sensitizing capacity of the allylic epoxides metabolically formed from conjugated dienes. We recommend that these structure-activity relationship rules are incorporated into in silico predictive databases and propose that the prediction of contact allergenic activity of suspected prohaptens is based on assessment of susceptibility to metabolic activation and chemical reactivity of potential metabolites.
