Cyclodextrins with biphenyl compounds

The effect of temperature, and of temperature and pH on the retention of a selected group of compounds using a beta-cyclodextrin column was studied. The results indicated that a plot of Ink vs. 1/T gave linear relationships for anthraquinone, methyl anthraquinone, ethyl anthraquinone, naphthalene and biphenyl using a mobile phase of methanol/water. However, a non linear relationship was observed for a selected group of dipeptides employing a mobile phase of methanol/ammonium acetate at the following pH s 1, 5.5 and 7. The retention times decreased with an increase in the temperature of the column except that for certain dipeptides the retention times increased. The separation factor (a) values decreased by approximately 10 with increase in column temperature from 25°C to 77°C. 

The dicarboxylic acid was obtained in 65% yield with 79% selectivity. Fortunately, there are better ways (see Chap. 6) to make this compound without the use of toxic carbon tetrachloride. This method gives 100% selectivity at 71% conversion in the reaction of biphenyl-4-carboxylic acid to form the 4,4 -biphenyldicarboxylic acid. /3-Cyclodextrin accelerates the platinum-catalyzed addition of triethoxysilane to styrene.231 The reaction is 100% complete in 30 min at 50°C with the cyclodextrin, but only 45% complete without it. The Wacker reaction of 1-decene produces several ketones owing to double-bond isomerization. If the reaction is run in a dimethylcyclodextrin, isomerization is reduced by faster reoxidation of palladium(O).232 The product 2-decanone is obtained with 98-99% selectivity (5.57). 

---