Synthesis of dibenzo-16-crown-5 compounds with pendant ester and ether groups
作者:David A. Babb、Richard A. Bartsch、James J. Collier、Dhimant H. Desai、Sadik Elshania、Mi-Ja Goo、Johnny L. Hallman、Gwi Suk Heo、Xiaowu Huang、Vincent J. Huber、Hong-Sik Hwang、Russell J. Johnson、Yung Liu、Michael J. Pugia、Qiang Zhao
DOI:10.1002/jhet.5570410503
日期:2004.9
related dibenzo-16-crown-5 lariat ethers with pendant ester and ethergroups are prepared. Structural variations within the series of alkyl lariat etheresters include changes in the O-alkyl group, attachment site and nature of the lipophilic group, and length of the spacer, which connects the estergroup to the polyether framework. Also synthesized are bis(crown ether) diesters with two dibenzo-16-crown-5
Preparation of nitriles from carboxylic acids: A new, synthetically useful example of the Smiles rearrangement
作者:Vincent J. Huber、Richard A. Bartsch
DOI:10.1016/s0040-4020(98)00581-x
日期:1998.8
mide with acyl chlorides in the presence of excess triethylamine produces the corresponding nitrile in good to fair yields. Mechanistic studies indicate that the reaction proceeds via a Smiles rearrangement of the initially formed N-(2,4-dinitrobenzenesulfonyl)amide to form the nitrile, 2,4-dinitrophenol and sulfur dioxide.
Separation of yttrium-90 from strontium-90 by solvent extraction with ionizable crown ethers
作者:Donald J. Wood、S. Elshani、H. S. Du、N. R. Natale、C. M. Wai
DOI:10.1021/ac00058a009
日期:1993.5.15
sym-Dibenzo-16-crown-5-oxyacetic acid and its analogues are selective for the extraction of Y3+ over Sr2+ from aqueous solutions into chloroform. The selectivity and the pH range of extraction are influenced by the structure of the ligand. The size of the macrocyclic cavity, the tether length of the lariat, the attachment of alkyl functional groups to the lariat, and the identity of the ionizable group can affect selectivity and extraction efficiency. When the carboxylic acid at the terminal end of the lariat is replaced by a hydroxamic acid, the selectivity for Y3+ over Sr2+ is significantly increased. Using these ionizable crown ethers as extractants, Y-90 fractions of greater than 99.9% purity can be obtained in a single solvent extraction step from solutions of Sr-90.