Oriental lacquer,poison ivy,and drying oils

From the oriental lacquer tree Toxicodendron vernicifluum, a sap (emulsion) is obtained the oil‐soluble components (urushiol) of which consist of a mixture of 3‐n‐pentadecylcatechols and very small amounts of 3‐n‐heptadecylcatechols. Urushiol is the basis of oriental lacquer. The sap is conditioned by removal of most of the water by specific techniques, and the clear liquid is called oriental lacquer. It is used in the Orient for coatings to produce exquisite art objects. Poison ivy also has as its active ingredients 3‐n‐pentadecylcatechols, but they have a high diene content, which does not cure effectively. In humans 3‐n‐alkylcatechols cause severe contact dermatitis. The components of drying oils are glycerin esters of fatty acids derived from the families of palmitic (hexadecanoic) and stearic (octadecanoic) acids. In the case of the urushiols, as well as of the glycerides of drying oils, high unsaturation (60%) in the form of trienes in the long aliphatic chains is essential for curing. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4327–4335, 2000     

二甲基二硫醚对Ni/Al_2O_3催化剂加氢性能的影响

考察了二甲基二硫醚(CH3SSCH3)对Ni/Al2O3催化剂上苯、环己烯和苯乙烯加氢活性的影响,并采用BET、XRD、H2-TPR、XPS、SEM和EA等手段对催化剂进行表征。实验结果表明,在CH3SSCH3存在下,Ni/Al2O3催化剂对苯和环己烯加氢迅速失活,且环己烯加氢对CH3SSCH3的耐硫性要略强于苯加氢,而苯乙烯中共轭烯烃的加氢转化率则维持100%长时间不变。CH3SSCH3的影响顺序为芳环单烯烃共轭烯烃。此外,通过设计实验研究了CH3SSCH3对催化剂的毒化机理,发现CH3SSCH3分子首先吸附在催化剂的表面,并发生氢解生成甲烷随尾气逸出,故CH3SSCH3分子中碳对催化剂的失活影响较小,而留下的硫原子则与镍活性组分发生相互作用,毒化催化剂。     

Synthesis and X-ray crystal structures of three new terpyridine-based Pb(II) complexes,cytotoxicity studies of {[Pb(ttpy)(μ-AcO)]2}(SCN)2

Synthesis and X-ray crystal structures of three new terpyridine-based Pb(II) complexes, {[Pb(ttpy)(μ-AcO)]₂}(SCN)₂ (1) (ttpy?=?4′-tolyl-2,2′:6′,2″-terpyridine), [Pb(Clphtpy)(AcO)(ClO₄)] (2), and [Pb(Clphtpy)(SCN)₂] (3) (Clphtpy?=?4′-(4-chlorophenyl)-2,2′:6′,2″-terpyridine), are described. The synthesized materials have been characterized, also, by CHN elemental analysis, ¹H NMR, and IR spectroscopy. The structural analyses showed that, in the solid state, the coordination number of Pb(II) in 1, 2, and 3 are six, seven, and five, respectively. In the complexes, the lone-pair electrons of Pb(II) are stereochemically active and the coordination geometry of Pb(II) is hemidirected. The structures of the three complexes were compared and the effect of counter ion is described. The antibacterial activity of 1 and previously reported {[Pb(ttpy)(μ-AcO)]₂}(PF₆)₂ (1A) and {[Pb(ttpy)(μ-AcO)I]₂} (1B) were tested by minimum inhibitory concentration method to investigate the effect of counter ions on biological activity of the compounds. Also, cytotoxicity test was assessed using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay to determine the maximum non-toxic concentration of ttpy, Pb(II), and their complexes to HepG2 cells. Effective lead detoxification was observed for 1, 1A, and 1B.     

Synthesis of 8-deoxypumiliotoxin 193H and 9-deoxyhomopumiliotoxin 207O

The asymmetric synthesis of 8-deoxypumiliotoxin 193H and 9-deoxyhomopumiliotoxin 207O has been achieved, starting from both enantiomers of (+)- and (?)-10. Enantiomerically pure alcohols (+)- and (?)-10 were obtained by lipase-mediated kinetic resolution of racemic 10, which was prepared in 3 steps from new lactam-type building block (?)-8 in a highly stereoselective manner.