A New Type of Stepwise Countercurrent Distribution Train.

Abstract

Butene-2 produces higher concentrations of Cs isomers than does isobutylene.The branched Ci, olefins produce higher concentrations of C9 isomers than do the C4 olefins, but much lower concentrations than are produced by pentene-2.The branched C4 and Ce olefins produce higher concentrations of C10and-heavier components than do the linear C4 and C5 olefins.The position of unsaturation appears to be irrelevant, at least in the case of branched C5 olefins, since the alkylates produced are very similar.The HF alkylates contain higher concentrations of Cs isomers than do the H2S04 alkylates.The diastereomers of 2,3,4-trimethylhexane (21) are produced in an approximately 2:1 ratio regardless of feed composition or acid catalyst employed.

Bacitracin A. Isolation by counter double-current distribution and characterization

“…An automatic counter double-current distribution train with 58 tubes of 50-25-ml capacity was available for use in counter double-current distribution studies with bacitracin. The batchwise method of loading (Post and Craig, 1963) in multiple tubes was used. A 20-g sample of crude bacitracin was added Tube number figure 1: Countercurrent distribution pattern at 1029 transfers of the Internationa] Bacitracin Standard of 1964.…”

“…For these reasons and for further biological testing of the individual bacitracins, it appeared desirable to develop a way of separating larger amounts of the individual peptides than the procedure of Figure 1 would allow. Counter doublecurrent distribution (Post and Craig, 1963), a variation of countercurrent distribution, seemed ideal for this purpose. Since commercial pharmaceutical grade bacitracin is relatively inexpensive, percentage yield of a pure product was of secondary importance to isolation of a large quantity of very high purity bacitracin A.…”

Recent Progress on Countercurrent Chromatography Modeling

“…Dual flow CCC, in which both phases are pumped simultaneously in opposite directions was first suggested for CCD in 1963 [18] and first applied to CCC by Ito [19]. In fact, the dual countercurrent chromatography can be treated as the application of fractional extraction principle to CCC.…”

Biochemical Analysis

“…A modified design of an automatic countercurrent distribution train which permits the transfer of both upper and lower phase simultaneously in opposite directions was reported (391). By appropriate selection of train length and tube size, a through-put of 10 liters of each phase per hour could be obtained.…”