Product yields with temperature heating rate

The yields of the different materials obtained by pyrolysis vary with the species of woods used and the type of equipment and system employed. Manipulation of three variables, mainly the temperature, heating rate, and gas residence time, can greatly alter the relative proportions of the gas, liquid, and char produced. For example, the oil and tar yields can be varied between 1 and 40 percent and the char between 40 and 10 percent or less. Low temperatures favor liquids and char, low heating rates favor gas and char, and short gas residence favors liquids. Conversely, high temperatures favor gas, high heating rates favor liquids, and long gas residence times favor gas. Thus, the various product fractions can be preferentially manipulated by proper combinations of these variables. 

Acetanilide from acetophenone. Dissolve 12 g. of acetophenone in 100 ml. of glacial acetic acid containing 10 g. of concentrated sulphuric acid. To the stirred solution at 60-70°, add 9 8 g. of sodium azide in small portions at such a rate that the temperature does not rise above 70°. Stir the mixture with gentle heating until the evolution of nitrogen subsides (2-3 hours) and then allow to stand overnight at room temperature. Pour the reaction mixture on to 300 g. of crushed ice, filter the solid product, wash it with water and dry at 100°. The yield of crude acetanilide, m.p. 111-112°, is 13 g. Recrystallisation from water raises the m.p. to 114°. 

Polymerization rate, yield, and intrinsic viscosity of the macromolecular products depend on monomer structure, initiator, reaction temperature, and solvent. The reaction rate and reagent conversion sharply increased in water in the presence of a redox system [FeS04-(NH4)2S208-K2S205]. Monomers 475 and 476 under these conditions polymerize virtually instantly with considerable heat liberation. Polymerization of iV-isopropenyltetrazoles 480-483 yielded polymers of relatively low molecular weight as compared to those obtained from 1-vinyltetrazoles 475-479 <2003RCR143>. 

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