Heating, under pressure, procedure

Trichloropyridazine when heated under pressure with NHs/EtOH yielded a mixture of aminodichloropyridazines, believed to be the 4- and 5-amino isomers. A modified procedure gave a mixture of 4-amino-3,5-dichloropyridazine (35%) and 5-amino-3,4-dichloropyridazine (38%) and structures of both isomers have been proved through further transformations. With equimolar amount of methoxide the 5-chlorine is displaced, but with 2 equivalents of methoxide 3,4,5-trichloropyridazine yielded a mixture of 4-chloro-3,5-dimethoxy- (25%) and 3 - chloro - 4,5 - dimethoxypyridazine (41%). ... 

The old method of heating the calcium salts of formic and a second carboxylic acid for aldehyde formation has been modified by the use of a catalytic decomposition technique. By this scheme, the acid vapors are passed over thorium oxide, titanium oxide, or magnesium oxide at 300° or the acids are heated under pressure at 260° in the presence of titanium dioxide. In the latter procedure, non-volatile acids can be used. With aliphatic acids over titanium oxide, reaction occurs only when more than seven carbon atoms are present, the yields increasing with increase in the molecular weight (78-90%). Aromatic-acids having halo and phenolic groups are converted in high yields to aldehydes, e.g., salicylaldehyde (92%) and p-chlorobenzaldehyde (8S>%). Preparation of a thorium oxide catalyst has been described (cf. method 186). 

The procedures as outlined are applicable to both the aliphatic and aromatic series. They are superior to the common interchange method in that they avoid the fractional distillation which is very troublesome in the aliphatic series. They have been used in numerous instances and can be adapted to give mixed anli3"drides. Benzoic anhydride has been obtained, by closely related procedures, from benzoic acid and benzoyl chloride by heating under reduced pressure or in the presence of zinc chloride. 

The procedure above is a modification of the method of Ullmann and Stein for the same compound. Sartoretto and Sowa used the same general method. The need for a catalyst can be avoided by heating a mixture of guaiacol potassium, guaiacol, and chlorobenzene at 200° under pressure. Ullmann and Stein have prepared the compound by using phenol, o-bromoanisole. 

Procedure A mixture of phenol, formaldehyde and ammonia (nearly 1-3 per cent on the weight of phenol) is made heat under reflux at about 100°C for 25-60 minutes and water is separated by distillation under reduced pressure. After removing water, the resin is obtained as a hard and brittle solid. 

The procedure described is based on one reported by Alexander and Schniepp. 4,4 -Dichlorodibutyl ether has also been prepared by the action of thionyl chloride on tetrahydrofuran and by heating 4-chlorobutanol and hydrogen chloride under pressure. ... 

The synthetic procedure is very simple to perform acetylene is passed under atmospheric pressure into a heated solution of reactants upon stirring. The reaction proceeds to completion over 3-8 hr on average, Naturally, autoclave can be used, since, under pressure, the process comes to an end more quickly. 

Procedures for deprotection of THP-ethers. Use of methanolic hydrochloric acid. The THP-ether (0.2 mol) was dissolved in methanol (200ml) and concentrated hydrochloric acid (30 ml), and the mixture heated under reflux for 2 hours. After cooling, the solution was neutralised by the addition of an excess of sodium hydrogen carbonate, diluted with ether (200 ml), filtered and the ether evaporated. The residue was dissolved in ether, washed twice with water, dried and evaporated. The deprotected alcohol was distilled under reduced pressure. 

The complexes may also be prepared by the addition of a solution of carboxylic ligand to an equivalent amount of (i) a lanthanide carbonate [28], (ii) hydroxide [29] or (iii) oxide [30] with a slight excess of the latter. The insoluble part is filtered and the filtrate evaporated to obtain crystalline complex. Anhydrous lanthanide complexes of small chain carboxylic acids may be prepared by (i) the dissolution of lanthanide carbonate in excess of the carboxylic acid, followed by heating to obtain complete dissolution of the suspension and partial evaporation of the solution to obtain the crystals [31], (ii) anhydrous lanthanide is converted into the corresponding monochloroacetate by the addition of an excess of monochloroacetic acid, followed by heating under reflux at reduced pressure for 2 h. Then ether is added to precipitate the salt [32], (iii) the addition of dimethyl formamide and benzene to lanthanide acetates and distillation of the water azeotropes to obtain anhydrous complexes. The last procedure yielded lighter lanthanide complexes solvated with dimethyl formamide [33], The DMF may be removed by heating in a vacuum at 120°C. 

The initial research objectives included developing a simple experimental procedure to study how the graft polymers, polystyrene, and a commercial phenol formaldehyde resin interact when combined with wood under heat and pressure. Two-ply lap shear test specimens were used for a comparative test. 

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