Showing papers on "Phosphotungstic acid published in 1983"

Preparation of polytetramethylene glycol

Abstract: PURPOSE:To obtain the titled compd. by polymn. of tetrahydrofuran without corrosion to the apparatus with a slight amt. of a catalyst under mild reacting conditions, by using the catalyst comprising a combination of a heteropoly acid with a carboxylic acid anhydride or chloride. CONSTITUTION:A novel catalyst is formed by the combination of a heteropoly acid (e.g., phosphotungstic acid) with a carboxylic acid anhydride or chloride (e.g., acetic anhydride, acetyl chloride). In the presence of the resulting novel catalyst, tetrahydrofuran is polymerized to yield polytetramethylene glycol. The amount of the heteropoly acid is 1.0-10.0wt%, pref. 1.0-5.0wt%, relative to that of tetrahydrofuran. The amount of the carboxylic acid anhydride or chloride is 10-50wt%, pref. 10-20wt%, relative to that of tetrahydrofuran.

Manufacture of colored aluminum powder

Abstract: PURPOSE: To obtain Al powder having a desired color tone by adsorbing an acid contg a multivalent metal or a mordant on Al powder before dyeing with a basic dye CONSTITUTION: An acid contg a multivalent metal such as niobic acid, tantalic acid, antimonic acid, molybdic acid, phosphomolybdic acid, tungstic acid or phosphotungstic acid or a mordant such as a condensation product of tannic acid or phenol with sulfur is adsorbed on Al powder The Al powder having the adsorbed acid or mordant is dyed with a basic dye The basic dye is converted into a chelate compound by bonding to said acid or mordant, and Al powder having a desired color tone is obtd COPYRIGHT: (C)1985,JPO&Japio

Depolymerization of polyoxymethylene glycol

Abstract: PURPOSE: To obtain the titled compound useful as a raw material of polyurethane, in high activity, without causing the corrosion of the apparatus, by carrying out the depolymerization of polyoxytetramethylene glycol using a catalyst comprising a heteropolyacid containing a specific amount of water coordinated or mixed to the acid. CONSTITUTION: Tetrahydrofuran is produced by the depolymerization of polyoxytetramethylene glycol (PTMG), using a catalyst comprising a heteropolyacid (e.g. phosphomolybdic acid, phosphotungstic acid, etc.) containing ≤15mol of water coordinated or mixed to 1mol of the acid. The amount of the heteropolyacid is preferably ≥0.1wt%, especially ≥1wt% of the PTMG, and the reaction is carried out at 50W200°C, preferably 80W150°C. The process is also useful to obtain a PTMG having sharp molecular weight distribution. COPYRIGHT: (C)1985,JPO&Japio