Sunscreen compositions are described which contain certain 5-phenylpentadienoate esters which act as UV filters when incorporated in a carrier in amounts ranging from 0.1-50% by weight.
Rasta Resin-PPh3 and its Use in Chromatography-Free Wittig Reactions
作者:Patrick Toy、Peter Leung、Yan Teng
DOI:10.1055/s-0030-1258130
日期:2010.8
Rasta resin-PPh3 (RR-PPh3), a new heterogeneous polystyrene-based phosphine, has been synthesized and used in one-potWittig olefination reactions of aldehydes. In these reac- tions an excess of RR-PPh3 was used for the in situ generation of the phosphorane reactant, and allowed for isolation of a high yield of very pure alkene product after only filtration and solvent re- moval. The excellent results
Rasta 树脂-PPh3 (RR-PPh3) 是一种新型多相聚苯乙烯基膦,已被合成并用于醛的单锅 Wittig 烯化反应。在这些反应中,过量的 RR-PPh3 用于原位生成正膦反应物,并允许在仅过滤和去除溶剂后分离出高产率的非常纯的烯烃产物。本研究中获得的优异结果归因于 rasta 树脂结构的柔韧性,这使得它比以前用于在 Wittig 反应中支持膦试剂的其他异质聚苯乙烯材料更少依赖于溶胀。碳-碳双键构成有机化学中的中心官能团之一,合成这种键的重要方法是Wittig反应。这种转化涉及使用磷烷试剂将亚烷基转移到醛或酮基团,同时将原始羰基氧转移到磷(方案 1)。1 通常,正膦是通过叔膦(通常为 PPh3)与卤代烷反应制备的,然后用适当的碱对由此形成的鏻盐进行去质子化。
Reactivity of substituted and unsubstituted diphenylphosphonium diylides towards carbonic acids derivatives
作者:H.J. Cristau、M. Taillefer
DOI:10.1016/s0040-4020(97)10360-x
日期:1998.2
delimit the scope of application of diphenylphosphonium diylides, their reactivity towards carbonicacid derivatives was investigated. Non-stabilized diylides react with ethyl carbonate to give new monoylide intermediates which lead, by in situ Wittig reaction with carbonyl compounds, to the synthesis of α,β-unsaturated esters or acids the double bond being di- or trisubstituted. The reaction proceeds in
Highly <i>E</i>-Selective Solvent-Free Horner-Wadsworth-Emmons Reaction for the Synthesis of α-Methyl-α,β-Unsaturated Esters Using Either LiOH·H<sub>2</sub>O or Ba(OH)<sub>2</sub>·8H<sub>2</sub>O
作者:Kaori Ando、Wakana Isomura、Nariaki Uchida、Kanae Mori
DOI:10.1246/bcsj.20220052
日期:2022.6.15
Horner-Wadsworth-Emmons reaction, which stirs a mixture of aldehyde, phosphonate reagent 1, and a base without solvent. The reaction of aromatic aldehydes and triethyl 2-phosphonopropionate 1a using LiOH·H2O gave 95-99% E-selectivity in 83-97% yield. The reaction of 1a with aliphaticaldehydes gave 92-94% E-selectivity except for α-branched aldehydes, and the selectivity was improved to 97-98% using ethyl 2-(diis
( E )-α-甲基-α,β-不饱和酯通过Horner-Wadsworth-Emmons 反应制备,该反应在无溶剂的情况下搅拌醛、膦酸酯试剂1和碱的混合物。芳香醛和 2-膦酰基丙酸三乙酯1a使用 LiOH·H 2 O 反应得到 95-99% E-选择性,产率为 83-97%。1a与脂肪醛的反应产生92-94% E-选择性,除了 α-支链醛,使用 2-(二异丙基膦酰基)丙酸乙酯1b将选择性提高到 97-98% 。使用 2-膦酰基丙酸三异丙酯1c改善了与 α-支链脂肪醛的反应和Ba(OH) 2 ·8H 2 O,得到98->99%的E-选择性和高产率。在THF中使用Ba(OH) 2 ·8H 2 O的HWE反应也以高产率高度选择性地得到( E )-α-甲基-α,β-不饱和酯。
Abrasive article, a process for its manufacture, and a method of using it
申请人:MINNESOTA MINING AND MANUFACTURING COMPANY
公开号:EP0650807A1
公开(公告)日:1995-05-03
An abrasive article having a sheet-like structure having at least one major surface having deployed thereon a plurality of individual abrasive composites, each abrasive composite characterized by a plasticizer and a plurality of abrasive particles dispersed in a binder, wherein said binder is formed by polymerizing a binder precursor and said plasticizer being combined with said binder precursor prior to said polymerizing in an amount of 30 to 70 parts plasticizer per 100 parts by weight of the combined binder precursor and plasticizer. There is also a method of using such as abrasive article to reduce the surface finish of a workpiece and a process of making the abrasive article.