Phthalic anhydride apparatus

As apparatus for the batch process, an enamel or steel reactor with an agitator and pressure steam or oil heating suffices. Apparatuses used in the continuous synthesis in the presence of solvents and in the bake process are described in [50] and [51,52], respectively. The choice of process depends on the availability and cost of the starting materials phthalodinitrile or phthalic anhydride. Although the phthalodinitrile process has certain advantages over the phthalic anhydride process, the latter is preferred worldwide because of the ready accessibility of phthalic anhydride. In this process the molar ratio of phthalic anhydride, urea, and cop-per(i) chloride is 4 16 1, with ammonium molybdate as catalyst. The mixture is heated in a high-boiling solvent such as trichlorobenzene, nitrobenzene, or kerosene. The solvent is removed after the formation of copper phthalocyanine. Fre-... 

The catalytic oxidation of naphthalene can easily be carried out in the laboratory, although the amount of phthalic anhydride which can be prepared in one operation is insignificant. It is of great importance that the correct temperature be maintained and that a suitable catalyst be used. Special attention must be given to the apparatus if the preparation in the laboratory is to succeed. Furthermore, it is highly desirable to use a Cottrel precipitator to collect the reaction product completely. This apparatus will collect even the fine particles, which otherwise would be lost. 

A) Preparation of o-Benzoylbenzoic Acid (Sm.). Arrange apparatus as in Experiment 62 (A). Place in a reaction tube 3 g of powdered phthalic anhydride and 15 ml of pure anhydrous benzene. Set under the tube a small beaker of ice water so that it can be raised to immerse tube and moderate the reaction if necessary. Weigh rapidly in a dry test tube 6 g of aluminum chloride, and cork immediately. Add about a fifth of the aluminum chloride by raising momentarily the cork of the reaction tube. If the reaction does not begin within a few minutes, raise a 250-ml beaker half-... 

That such an apparatus was not very satisfactory may be easily recognized from a consideration of the characteristics of the oxidation reaction. In oxidations such as that of naphthalene to phthalic anhydride there is a specific and rather narrow temperature range within which the best results are obtained. Depending upon what catalyst is used there is some... 

The principles made use of in the design of the catalytic oxidation apiiaratns described for use in phthalic anhydride and maleic acid production may be applied to the design of apparatus for the oxidation to partial oxidation products of anthracene, toluene, and other organic compounds derived from coal-tar, petroleum, and miscellaneous sources. 

A. Methyl (S)-2-phthalimido-4-methylthiobutanoate. Into a 2-L, round-bottomed flask fitted with a Dean-Stark apparatus, reflux condenser, and drying tube containing calcium chloride are placed L-methionine methyl ester hydrochloride (50.0 g, 0.25 mol, Notes 1 and 2), phthalic anhydride (37.1 g, 0.25 mol), triethylamine (100 mL, 0.72 mol), and toluene (1 L). The mixture is magnetically stirred and heated under reflux for 4.5 hr at which point approximately 4.5 mL of water has separated. The reaction mixture is allowed to cool to room temperature and the precipitated triethylamine hydrochloride (34 g) is collected by suction filtration. The filtrate is washed with four 300-mL portions of 1 N aqueous hydrochloric acid followed by three 300-mL portions... 

Noncatalytic oxidation of the aromatic hydrocarbons is slow at temperatures below 500 C. Benzene is not vigorously oxidized in glass apparatus until temperatures near 700°C are reached. Under similar conditions, toluene is noticeably oxidized at 650 0, and xjdene at 575 0. Even with an active catalyst such as vanadium pentoxide, a temperature of 400-450 0 is required for the commercial oxidation of naphthalene to phthalic anhydride by air. Furthermore, quantities of air from one to three times that theoretically necessary for the conversion must be used. This means that 20-60 moles of air must be used per mole of naphthalene in the reaction mixture. 

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