Reference

Method for processing high-boiling by-products of isoprene production

Method for processing high-boiling by-products of isoprene production. Bart, E. V.; Batalin, O. F.; Troitsky, A. P.; Skachkova, N. A.; Lebedev, V. M.; Trifonova, R. P. (USSR ). Brit. GB 1474844 25 May 1977,15 pp. (English). (United Kingdom). CODEN: BRXXAA. CLASS: IC: C07C001-20. APPLICATION: GB 75-13433 2 Apr 1975. DOCUMENT TYPE: Patent CA Section: 38 (Elastomers, Including Natural Rubber) Section cross-reference(s): 23 The high-boiling by-products obtained at the 1st stage of the prodn. of isoprene (I) [78-79-5] by the dioxane method were converted to a mixt. of I, isobutylene (II) [115-11-7], and HCHO [50-00-0] in 2 stages. In the 1st, the by-products in the vapor phase were contacted with H2O in a 1:1-2 wt. ratio at 250-90.degree. over Al2O3 [1344-28-1]. In the 2nd, the resultant vapor mixt. was heated at 315-60.degree. over Ca3PO4 [10103-46-5]. The degree of conversion of the high-boiling by-products was 80-90% and the products included I 22.4-23.3, II 7-9, HCHO 25.1, methyldihydropyran 7.1-8.0, dimethyldioxane 3.4-3.8, MeOH 4.8-7.9, and Me3COH 1.9-2.6%.

An ultrastructural study of the effects of acidic phospholipid substitutions on calcium phosphate precipitation in anionic liposomes

An ultrastructural study of the effects of acidic phospholipid substitutions on calcium phosphate precipitation in anionic liposomes. Heywood, Brigid R.; Eanes, Edward D. (Sch. Chem., Univ. Bath, Bath BA2 7AY, UK). Calcif. Tissue Int., 50(2), 149-56 (English) 1992. CODEN: CTINDZ. ISSN: 0171-967X. DOCUMENT TYPE: Journal CA Section: 13 (Mammalian Biochemistry) Section cross-reference(s): 6 A model membrane system was used to investigate the ability of specific membrane constituents to modulate the pptn. of calcium phosphate. Intraliposomal pptn. was induced in phosphate-encapsulated liposomes composed of 7:2:1 M mixts. of phosphatidylcholine (PC), dicetyl phosphate (DCP), and cholesterol (Chol) by ionophore-supported (X-537A) Ca2+ uptake. Extraliposomal pptn. occurred when these reactions were initiate in metastable external solns. In this case, the endogenously formed crystals penetrated throughout the enclosing lipid bilayers and seeded the external soln. phase. TEM was used to monitor the effect of acidic phospholipids [phosphatidic acid (PA), phosphatidylserine (PS), phosphatidylinositol (PI), and phosphatidylglycerol (PG)] on the pptn. reactions when these mol. species were incorporated into the liposome membranes. Compared with pptn. reactions in 7PC:2DCP:1Chol liposomes contg. no acidic phospholipids, calcium phosphate formation in the presence of monoester phosphate (PA) and amino- (PS) phospholipids was inhibited. These and other results suggest that PS may be localized preferentially on the outer membrane surface in the presence of DCP but concd. on the inner aspect in its absence. No such interactions were obsd. in PI- or PG-contg. liposomes. The liposome-mediated pptn. events were not affected in these prepns.In this experiment, several chemicals are used like 10103-46-5 and 3614-36-6 the data suggest that the inhibition of calcium phosphate formation resulted from specific interactions between the nascent crystals and lipid species present in the liposome membrane. The mol. conformation of the head group, the mol. geometry of the phospholipids in the membrane, and the relative affinity of the incorporated species for Ca2+ were key determinants of these interactions. .