Potassium hydroxide pretreatment

The cmde phthaUc anhydride is subjected to a thermal pretreatment or heat soak at atmospheric pressure to complete dehydration of traces of phthahc acid and to convert color bodies to higher boiling compounds that can be removed by distillation. The addition of chemicals during the heat soak promotes condensation reactions and shortens the time required for them. Use of potassium hydroxide and sodium nitrate, carbonate, bicarbonate, sulfate, or borate has been patented (30). Purification is by continuous vacuum distillation, as shown by two columns in Figure 1. The most troublesome impurity is phthahde (l(3)-isobenzofuranone), which is stmcturaHy similar to phthahc anhydride. Reactor and recovery conditions must be carefully chosen to minimize phthahde contamination (31). Phthahde [87-41-2] is also reduced by adding potassium hydroxide during the heat soak (30). 

It has been claimed that the elimination of tosylates of 3a-alcohols in 5jS-series gives 3-oleflns with high selectivity. However, the homogeneity of these products is questionable, in view of recent findings concerning the ehmination of 3-chloro compounds (see below) and Fieser s results with the elimination of methyl lithocholate tosylate (ref. 232, cf. ref. 233). Neutral alumina may also be used to effect elimination of tosylates of 3j5-alcohols if the alumina is pretreated with potassium hydroxide the inverted alcohol is the predominant product. 

Example 4. Glycolysis of Polyurethanes with Propylene Oxide after Pretreatment with a Mixture of Diethanolamine and Potassium Hydroxide.57 Polyurethane scrap was treated with a mixture of diethanolamine and potassium hydroxide at a temperature between about 80 and 140° C with stirring to form an intermediate product. The weight ratio of the scrap PUR polymer to the mixture of diethanolamine and potassium hydroxide was from about 15 1 to 30 1. The intermediate product was reacted with propylene oxide at a temperature of from about 100 to 120°C in a closed reaction vessel to form a polyol. The propylene oxide was added at a rate to maintain a pressure of from about 2 to 5 atm (29-73 psi). The progress of the reaction was followed by following the change of pressure with time. When the pressure remained constant, the reaction of the intermediate product with propylene oxide was considered to be complete. The crude polyol obtained was treated with 10 mol % excess of dodecylbenzene sulfonic acid to remove the potassium hydroxide. 

Mobile phases useful for suppressed conductivity detection of anions include sodium hydroxide, potassium hydroxide, and the sodium and potassium salts of weak acids such as boric acid. In nonsuppressed conductivity detection, the ionic components of the mobile phase are chosen so that their conductivities are as different from the conductivity of the analyte as possible. Large ions with poor mobility are often chosen, and borate-gluconate is popular. For cations, dilute solutions of a strong acid are often used for nonsuppressed conductivity detection. For more information on the application of electrochemical detection to inorganic analysis, see Ion Chromatography Principles and Applications by Haddad and Jackson,17 which provides a comprehensive listing of the sample types, analytes, sample pretreatments, columns, and mobile phases that have been used with electrochemical detection. 

Palladium black was prepared from palladium nitrate and formaldehyde solution by dropwise addition of potassium hydroxide solution (50 wt. %) at about 10°. The solution and precipitate were warmed at about 60° and the precipitate washed several times by decantation. It was then placed in a Soxhlet extractor and washed for 48 hr. (about 100 times). The precipitate was then dryed at 110°. The palladium-silver system is known to be one of complete miscibility (3). Alloys of silver-palladium were prepared following a procedure discussed elsewhere 4). Their preparation involved a low-temperature coprecipitation of both metals from a solution containing proper amounts of their nitrates. Alloy formation was checked by means of x-ray diffraction patterns which were obtained with Cu-Ka radiation. The computed lattice constants are shown in Fig. 1 to be a linear function of the alloy composition. Hydrogen, used for pretreatment of all samples, was obtained from a commercial tank and purified by passage through a Deoxo unit, magnesium perchlorate, and a charcoal trap immersed in liquid nitrogen. 

In the second method. Stone et al. [84] copolymerized monomer 4-2 with TFS (Fig. 2.17) by emulsion polymerization in 21% isolated yield. The optimized ratio between TFS and the dimethyl phosphonate-substimted a,, -trifluorostyrene monomer in the copolymer 4-5 was 2.4 1. The molecular weights of the resulting copolymer were 38,100 and 105,900g/mol for and respectively. Homo-polymer 4-3 (membrane A) was hydrolyzed under acidic conditions (hydrochloric acid in dioxane, 100 °C, 20 h). The yield and the equivalent weight of acid functions were 95% and 130 g/mol, respectively. Copolymer 4-4 was hydrolyzed by the authors using two processes (i) basic conditions (potassium hydroxide, 84 °C, 64 h), membrane Cl, and (ii) acidic conditions with a DMF pretreatment, membrane C3. Finally, the authors concluded that the best results were obtained with an acidic hydrolysis and that membranes based on sulfonic acid-a,, -trifluorostyrene gave better results than those obtained from the phosphonic acid homolog. 

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