Naphthalene heat removal

Dependence upon radiation for heat removal in the case of the old form of reactor was essential since even with the large excesses of air used the heat capacity of the total exit products was insufficient to remove the heat of reaction, especially when die air-naphthalene mixture had been preheated to approximately 350° C. prior to entering the catalyst zone. With the present method of temperature control and heat removal the heat of reaction amounts to about 10,000 B.t.u. per pound of naphthalene fed to the converter. As the proportion of naphthalene burned to com-... 

The very large amount of heat removed in such a converter, winch is about three feet in diameter and contains somewhat over 1000 catalyst tubes three feet long, may be calculated from the heat of oxidation of naphthalene. Although the heat of oxidation of naphthalene to phthalic anhydride is about 6000 B.t.u. per pound of naphthalene, the amount of concurrent total combustion which occurs in practice serves to bring this heat nearer to 10,000 B.t.u. per pound of naphthalene. On the basis of a 1600-pound-per-day production of phthalic anhydride about 21 million B.t.u. would be generated in each converter and removed by the boiling mercury and as sensible heat by the hot exit products. 

A closed system for removing naphthalene from coke-oven gas in the final cooler is described by Kroll and Barry (1991). In this system, recycled water and fresh water are sprayed into the process gas at high flow rates to cool and saturate the gas with water. Naphthalene is condensed and collected with the water. The naphthalene is removed from the water by contact with liquid tar in a liquid-liquid extraction step at the bottom of the spray contactor. After naphthalene removal the water is pumped through an indirect heat exchanger (cooler) and recycled with fresh water makeup to the spray nozzles. 

Phthalic anhydride. Naphthalene is oxidized by air to phthalic anhydride in a Bubbling flmdized reaclor. Even though the naphthalene feed is in liquid form, the reaction is highly exothermic. Temperature control is achieved by removing heat through vertical tubes in the bed to raise steam [Graham and Way, Chem. Eng. Prog., 58, 96 (Januaiy 1962)]. 

A mixture of RhCl3 (0.2 g, 1 mmol), 2-cyanobenzamide (1.8 g. 12.3 mmol) and naphthalene (0.6 g, 4.7 mmol) was heated for 1 h and the resulting blue solid was Soxhlet extracted with glacial HOAc untii the washings were colorless, then dried at 100 C for 12 h to remove traces of HOAc yield 0.47g( 60%). 

Under N2, clean Li metal (0.17 g, 25 mmol) was placed in a round-bottom flask with a solvent mixture of MeOH (3 mL) and pcntan-t-ol (17 mL). The mixture was heated under N, until the reaction with Li was complete. Then, naphthalene-2,3-dicarbonitrilc (2 g, 11 mmol) was added to the mixture which turned green-brown the mixture was refluxed for 3h. The brown powder, obtained after cooling and removal of the solvent under reduced pressure, was dissolved in anhyd acetone (20 mL) and then hexane (70 mL) was added. The green precipitate was separated from the brown solution by filtration. This purification by precipitation was repeated twice. The green precipitate was placed in a Soxhlet extractor and extracted for 3 h with acetone (200 mL) in order to separate the product from the insoluble metal-free species and LiOH. The acetone solution was evaporated down to a volume of 20 mL. The product precipitated after the addition of hexane (70 mL). This latter purification step was performed several times yield 1.29 g (64%). 

Preparation. On a coml scale the nitration of naphthalene is carried out in two steps using a cylindrical jacketed reactor 1.6 x lm with a conical bottom. It is fitted with a discharge pipe 8cm in diameter and a stirrer which can be rotated at 85—90rpm. The jacket can be heated with steam or cooled with cold w. The cover is provided with an opening for the addn of naphthalene and a vent for the removal of gaseous prods... 

Dissolve 71 g. of P-methylnaphthalene in 460 g. (283 ml.) of A.B. carbon tetrachloride and place the solution in a 1 -litre three-necked flask equipped with a mechanical stirrer and reflux condenser. Introduce 89 g. of JV-bromosuccinimide through the third neck, close the latter with a stopper, and reflux the mixture with stirring for 16 hours. Filter ofiT the succinimide and remove the solvent under reduced pressure on a water bath. Dissolve the residual brown oil (largely 2-bromomethyl naphthalene) in 300 ml. of A.R. chloroform, and add it to a rapidly stirred solution of 84 g. of hexamine in 150 ml. of A.R. chloroform contained in a 2-litre three-necked flask, fitted with a reflux condenser, mechanical stirrer and dropping funnel maintain the rate of addition so that the mixture refluxes vigorously. A white solid separates almost immediately. Heat the mixture to reflux for 30 minutes, cool and filter. Wash the crystalline hexaminium bromide with two 100 ml. portions of light petroleum, b.p. 40-60°, and dry the yield of solid, m.p. 175-176°, is 147 g. Reflux the hexaminium salt for 2 hours with 760 ml. of 60 per cent, acetic acid, add 160 ml. of concentrated hydrochloric acid, continue the refluxing for 5 minutes more, and cool. Extract the aldehyde from the solution with ether, evaporate the ether, and recrystallise the residue from hot -hexane. The yield of p-naphthaldehyde, m.p. 69-60°, is 60 g. 

Reposition the test-tube clamp so that the test tube containing the solid naphthalene is again partially submerged in the boiling water bath. Heat the test tube until the naphthalene is melted and you can remove the thermometer and stirrer as a unit. CAUTION The thermometer, stirring wire, and test tube may be hot. Do not discard the naphthalene. Remove all the naphthalene from the stopper, thermometer, and stirrer by washing them with acetone. 

In a 1-1. round-bottomed flask is placed a mixture of 204.3 g. (1 mole) of finely divided phosphorus pentachloride and 132.8 g. (0.4 mole) of the disodium salt of naphthalene-1,5-disulfonic acid which has been dried previously at 140° for 48 hours (Note 1). The flask is provided with an air condenser which is fitted at the top with a calcium chloride drying tube. It is then placed in an oil bath which is heated to 110°, and the mixture is maintained at that temperature for 1 hour. The condenser is removed for brief intervals now and then during the heating period, and the reactants are stirred by means of a glass rod. At the end of the heating period, the product is a thick paste. 

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