Pyrolysis hydroxyl reaction with

With aldehydes, primary alcohols readily form acetals, RCH(OR )2. Acetone also forms acetals (often called ketals), (CH2)2C(OR)2, in an exothermic reaction, but the equiUbrium concentration is small at ambient temperature. However, the methyl acetal of acetone, 2,2-dimethoxypropane [77-76-9] was once made commercially by reaction with methanol at low temperature for use as a gasoline additive (5). Isopropenyl methyl ether [116-11-OJ, useful as a hydroxyl blocking agent in urethane and epoxy polymer chemistry (6), is obtained in good yield by thermal pyrolysis of 2,2-dimethoxypropane. With other primary, secondary, and tertiary alcohols, the equiUbrium is progressively less favorable to the formation of ketals, in that order. However, acetals of acetone with other primary and secondary alcohols, and of other ketones, can be made from 2,2-dimethoxypropane by transacetalation procedures (7,8). Because they hydroly2e extensively, ketals of primary and especially secondary alcohols are effective water scavengers. 

Connell and co-workers [87] investigated silicate siloxane fire retardant composites derived from vermiculite by reaction with hydroxyl-terminated polydimethylsiloxanes. Cone calorimetry was used to obtain HRR measurements. The results show that even at the highest irradiance levels the samples have very long ignition times. Ignition resistance deceases as the hydrocarbon content of the composite increases. The results from the cone calorimeter were obtained by Py-GC-MS, which show that small, volatile, silicone-containing molecules are formed during pyrolysis. 

Thermal Inactivation. Heating the wood surface to temperatures above 150 to 200°C definitely has been shown to cause poor adhesion with phenolic adhesives and, possibly, urea adhesives. Early research (60) verified that overheated wood was less wettable and tended to absorb less water from the adhesive. Whether this is caused by extractives, pyrolysis, oxidation of hydroxyl groups, or other chemical reactions at the wood surface has been the subject of much debate. Further, the mechanisms of thermal or "surface" inactivation may vary from species to species. 

Morterra and Low [14,15] have demonstrated that the methoxy groups (=Si-OCH3) can be fully substituted for the surface hydroxyl groups (=Si-OH) after treating silica surface in a methanol vapor at 700 K. They found that, upon the subsequent high-temperature pyrolysis of such samples (T> 1050 K), a series of chemical reactions proceed, with the following key reaction ... 

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