Preparation polyols

To achieve sugar-free preparations, polyols (sugar alcohol) are replacing sucrose as bulk sugar substitutes. They are not fermented by oral bacteria, hence noncariogenic. However, they are slowly hydrolyzed by the enzymes of the small intestine into their constituent monomers, which are only slowly and incompletely absorbed compared with... 

Water in Polyol Ester Oils The traditional hydrogen-bonded hydroxyl area, 3600-3150 cm was not successful for measuring water content in polyol ester, synthetic, lubricants. The spectra from prepared polyol ester samples indicate two peaks, at 3640 and 3550 cm corresponding to increases in water contamination... 

Roth, D. Continuous process for preparing polyol glycosides. US Patent Carr, M.E., Wing, R.E., Doane, W.M. Ceieal Chem. 68, 262-266 (1991)... 

A low viscosity, specially modified polyisocyanate is mixed with a previously prepared polyol dispersion when the isocyanate disperses into the polyol dispersion. This dispersion remains stable over a few hours, long enough to allow application. The chemistry of these systems is complex, and not fully disclosed, but can be based on both aliphatic and aromatic isocyanates, which are usually solvent-free. This is a new 2K technology now finding application in all markets using solvent-borne 2K urethane coatings. 

Figure 11.7 Different ways to prepare polyols for PU synthesis from soybean oil (G glycerol moiety with two more fatty acid derivatives attached).

Foams. Polyurethane foams are prepared by the polymerization of polyols with isocyanates. 

Plasticizers. About 2.5% of U.S. adipic acid consumed in 1988 was used in two basic types of adipic ester based plasticizers (195). Simple adipate esters prepared from Cg—alcohols are used especially as PVC plasticizers (qv). Eor special appHcations requiring low volatility or extraction resistance, polyester derivatives of diols or polyols are preferred. 

HydroxyethyUiydrazine (11) is a plant growth regulator. It is also used to make a coccidiostat, furazoHdone, and has been proposed, as has (14), as a stabilizer in the polymerization of acrylonitrile (72,73). With excess epoxide, polysubstitution occurs and polyol chains can form to give poly(hydroxyaLkyl) hydrazines which have been patented for the preparation of cellular polyurethanes (74) and as corrosion inhibitors for hydrauHc fluids (qv) (75). DialkyUiydrazines, R2NNH2, and alkylene oxides form the very reactive amineimines (15) which react further with esters to yield aminimides (16) ... 

MggAl2(OH) gC03 -4 H2O, is used to polymerize PO and is activated by calcining at 450°C, a quantitative yield of PPO is obtained at 50°C in 2 hours (96). At Olin, POLY-L polyols have been produced with reduced unsaturation, but the catalyst used to produce them has not been disclosed (97). The use of zinc hexacyanocolbaltate to prepare low unsaturation polyols has been reported (98). 

Neopentyl alcohol is useful for preparation of masked polyol siUcate esters, capable of releasing the polyol under moisture conditions, in moisture-curable one-component Hquid polyurethane compositions (90). 

Propylene oxide [75-56-9] (methyloxirane, 1,2-epoxypropane) is a significant organic chemical used primarily as a reaction intermediate for production of polyether polyols, propylene glycol, alkanolamines (qv), glycol ethers, and many other useful products (see Glycols). Propylene oxide was first prepared in 1861 by Oser and first polymerized by Levene and Walti in 1927 (1). Propylene oxide is manufactured by two basic processes the traditional chlorohydrin process (see Chlorohydrins) and the hydroperoxide process, where either / fZ-butanol (see Butyl alcohols) or styrene (qv) is a co-product. Research continues in an effort to develop a direct oxidation process to be used commercially. 

Propylene oxide has found use in the preparation of polyether polyols from recycled poly(ethylene terephthalate) (264), haUde removal from amine salts via halohydrin formation (265), preparation of flame retardants (266), alkoxylation of amines (267,268), modification of catalysts (269), and preparation of cellulose ethers (270,271). 

Etherification. The reaction of alkyl haUdes with sugar polyols in the presence of aqueous alkaline reagents generally results in partial etherification. Thus, a tetraaHyl ether is formed on reaction of D-mannitol with aHyl bromide in the presence of 20% sodium hydroxide at 75°C (124). Treatment of this partial ether with metallic sodium to form an alcoholate, followed by reaction with additional aHyl bromide, leads to hexaaHyl D-mannitol (125). Complete methylation of D-mannitol occurs, however, by the action of dimethyl sulfate and sodium hydroxide (126). A mixture of tetra- and pentabutyloxymethyl ethers of D-mannitol results from the action of butyl chloromethyl ether (127). Completely substituted trimethylsilyl derivatives of polyols, distillable in vacuo, are prepared by interaction with trim ethyl chi oro s il an e in the presence of pyridine (128). Hexavinylmannitol is obtained from D-mannitol and acetylene at 25.31 MPa (250 atm) and 160°C (129). 

Highly cross-linked polyol polytitanates can be prepared by reaction of a tetraaLkyl titanate with a polyol, such as pentaerythritol, followed by removal of the by-product alcohol (77). The isolated soHds are high activity catalysts suitable for use in the preparation of plasticizers by esterification and/or transesterification reactions. The insoluble nature of these complexes faciUtates their... 

Low viscosity urethane polymers have been prepared from castor od and polymeric isocyanates (82). These low mix viscosity systems are extremely usehd for potting electrical components where fast penetration without air voids, and fast dispensing cycles are desirable. Very low viscosity urethane systems containing castor polyols have been prepared for use in reclaiming water-logged buried telephone cable and for encapsulating telephone cable sphces (83—86). 

By varying molecular weight and functionaUty of the castor polyols and the type of isocyanate, a variety of clear and pigmented urethane coatings can be prepared. Copolymers of vinyl and castor-based urethane have also been reported for use as exterior coatings for plywood and flexible substrates (90) and for appHcation over steel, concrete, and wood substrates (91). 

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