Dihydroxyl poly

Polyurethane energetic block copolymers, (VIII), consisting of toluene diisocyanate, 1,4-butanediol, and dihydroxyl poly(3-azidomethyl-3-methylox-etane) were prepared by Sanderson et al. (3) and used as binders in high-energy compositions, especially rocket propellants. Poly(glycidyl nitrate) urethanes were previously prepared by the authors and are discussed (4). 

Tezuka et al. [56] further extended ESA-CF to other polymer systems. For instance, a,oi)-dihydroxyl poly(ethylene oxide) (PEO) was first converted to a,(D-di (p-toluenesulfonate)-PEO. The latter was converted to an ammonium with quinuchdine, followed by an ion-exchange reaction with tetra-n-butylammonium... 

Chandrasekhar, S., Narsihmulu, C., Sultana, S.S., Reddy, N.R. (2003) Osmium Tetrox-ide in Poly(ethylene glycol) (PEG) A Recyclable Reaction Medium for Rapid Asymmetric Dihydroxylation Under Sharpless Conditions. Chemical Communications, 1716-1717. 

The development of RuO as a aT-dihydroxylation catalyst is a relatively new and potentially important area. Until recently OsO has been the reagent of choice for this, but use of the cheaper RuO may well become competitive, though stringent reaction conditions need to be used because RuO is so much more powerful an oxidant than OsO. Reactions are much faster than for OsO, but so-called flash dihydroxylations in which low temperatures are used have been developed, and are the subject of much current research. There are several reviews including mechanistic aspects [7-9] and one on the synthesis of poly oxygenated steroids [6]. The scope and limitations of the procedure have been discussed [155, 156]. 

G. Poli, C. Scolastico, Formation of C-O Bonds by 1,2-Dihydroxylation of Olefinic Double Bonds, in Methoden Org. Chem. (Houben-Weyl) 4lh ed. 1952—, Stereoselective Synthesis (G. Helmchen, R. W. Hoffmann, J. Mulzer, E. Schaumann, Eds.), Vol. E21e, 4547—4599, Georg Thieme Verlag, Stuttgart, 1995. 

The first heterogeneous osmium catalyst applicable for asymmetric dihydroxylation reactions was described by Kobayashi and coworkers (Table 9, entry 1) [38, 39]. Osmium tetroxide was enveloped in a polymer capsule by microencapsulation techniques [40,41]. The asymmetric dihydroxylation of transmethylstyrene with poly(acrylonitrile-co-butadiene-co-styrene) microencapsulated (ABS-MC) osmium tetroxide as catalyst, NMO as the cooxidant, and (DHQD)2PHAL as the chiral ligand completed in 88% yield with 94% ee [38]. The catalyst and the chiral ligand were reused in five consecutive runs without loss of activity. However, the use of NMO as cooxidant required the slow... 

Ionic polymers 120 containing a mesylate anion were prepared by the quaterniza-tion of poly(4-vinylpyridine/styrene) 118 with tri(ethylene glycol) monomesylate monomethyl ether 119. These polymers were used to immobilize OSO4, as shown in Scheme 3.33. The resultant polymer 122 showed excellent catalytic performance in the Sharpless asymmetric dihydroxylation of styrene derivatives [63]. For example, 123 was dihydroxylated to styrene glycol 124 in 88% yield with 99% ee. 

At the end of the reaction, addition of tort butyl methyl ether precipitated the polymer, which was removed by filtration, the product remaining in solution. The recovery of the polymer was 98%. It could be used repeatedly with almost no change in enantioselectivity or yield. (The use of ultrafiltration to separate the polymer would eliminate the need for the ferf-butyl methyl ether.) A similar dihydroxylation in which the cinnamate substrate was part of an insoluble poly-... 

PolyDBOE can be converted into its dihydroxyl derivative, in which the hydroxyl groups are either in cis or trans position. Thus, epoxidation of polyDBOE with m-chloroperbenzoic acid, followed by hydrolysis, leads to poly(trans-3,4-dihydroxy-tetrahydropyran-6.2-diyloxymethylene) ... 

Some researchers analyzed the possibility of using complexes with modified poly(ethylene glycol)s in the Sharpless asymmetric dihydroxylation. The application of alkaloid-modified monomethyl ethers of poly(ethylene oxide)s 33-36 in osmium tetroxide-catalyzed ligand-accelerated asymmetric dihydroxylation ensures considerable enantioselectivity and much higher activity [70]. 

The positive ions MALDI-TOF spectrum of poly(butylene adipate diol)s, made by bulk polymerization of terephthaloyl chloride with a molar excess of 1,4 butanediol, shows only one series of peaks, extending over mass range 1000-6000 Da. These may be assigned to dihydroxyl-terminated oligomers. ° ... 

Two other novel poly(bis[2]catenane)s 38 and 39 were synthesized by Stoddart and coworkers (Scheme 17.12) [97], who employed the same template-directed strategy to prepare the dihydroxyl-functionalized [2]catenane monomers 36 and 37. The subsequent polymerization of 36 and 37 with bis(4-isocyanatophenyl)methane successfully afforded poly(bis[2]catenane)s 38 and 39. Based on the results of GPC analyses, 38 and 39 had the same Mn values of 45.0kDa (DP = 15). 

Herrmann and coworkers reported on the preparation of immobilized OSO4 on poly(4-vinyl pyridine) and its use in the dihydroxylation of alkenes by means of hydrogen peroxide [35]. However, the problems of gradual polymer decomposition and osmium leaching were not solved. 

Toroti, M., Olayemi, J.Y., Adeniyi, J.B., Peters, O. The photooxidative degradation of poly (vinylchloride)—2. The stabiUsing action of dibutyltin maleate and tris-nitro (1,3-dihydroxyl-2-hydroxymethyl-2-nitropropane) on PVC from ultraviolet light radiation. 

Poly (olefin-ester) multiblock copolymers belong to a quite new and fast developing class of polyester elastomers [58-60]. The copolymer with PBT rigid segments and flexible polyisobutylene (PIB) segments was prepared by polycondensation in the molten state with DMT, BD, and functionalized PIB, in the presence of titanium tetrabutoxide as catalyst. a,o -Dianhydride [58] and dihydroxyl-terminated PIB of molecular weights 1000, 2200, 4800, and 10000 g/mole were used (Schemes 17 and 18). A multiblock copolymer with PBT and... 

Poly(dihydroxyl- I, 4-phenylene), Polyhydroquinone DMF (partially) Acetone, chloroform, ethanol 181... 

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