Thermometer immersion

Dichlorobutane. Place 22-5g. of redistilled 1 4-butanediol and 3 ml. of dry pyridine in a 500 ml. three necked flask fitted with a reflux condenser, mechanical stirrer and thermometer. Immerse the flask in an ice bath. Add 116 g. (71 ml.) of redistilled thionyl chloride dropwise fix>m a dropping funnel (inserted into the top of the condenser) to the vigorously stirred mixture at such a rate that the temperature remains at 5-10°. When the addition is complete, remove the ice bath, keep the mixture overnight, and then reflux for 3 hours. Cool, add ice water cautiously and extract with ether. Wash the ethereal extract successively with 10 per cent sodium bicarbonate solution and water, dry with anhydrous magnesium sulphate and distil. Collect the 1 4-dichloro-butane at 55-5-56-5°/14 mm. the yield is 35 g. The b.p. under atmospheric pressure is 154 155°. 

The crude enamlne (1) is dissolved in 20 mL of toluene, and the solution is transferred (Note 3) to a 100-mL, three-necked flask equipped with a magnetic stirring bar, 50-mL dropping funnel, reflux condenser protected with a calcium chloride tube, and a thermometer immersed in the solution. A solution of 13.2 g (0.048 mol) of diphenyl phosphorazidate (Note 4 uarntng) in 20 mL of toluene is added with stirring during 30 min di11e the reaction temperature is maintained at about 25°C. The mixture is stirred for 4 hr at 25 C and heated at reflux for 1 hr. The mixture is transferred to a 300-mL, round-bottomed flask and most of the toluene is removed under reduced pressure to yield 23.7 g of a reddish-brown oil, 2 (Note 5). 

A 1-liter flask is equipped with a magnetic stirrer, a thermometer immersed in the reaction mixture, and a drying tube. In the flask is placed 100 ml of anhydrous pyridine, and the flask is cooled in an ice-water bath to 15-20° (lower temperatures impede the complex formation). Chromium trioxide (80 g) is added in small portions to the stirred solvent at a rate so as to keep the temperature below 30°. After about one-third of the chromium trioxide has been added, the yellow complex begins to precipitate. At the end of the addition (about 1 hour), a slurry of the yellow complex in pyridine remains. (This form of the complex is apparently a microcrystalline form and is very difficult to handle.)... 

A l-Iiter, three-necked, round-bottom flask is equipped with a mechanical stirrer, a thermometer immersed in the reaction mixture, a dropping funnel, and a gas vent. In the flask is placed a mixture of 96% sulfuric acid (25.5 ml, 470 g, 4.8 mole), carbon tetrachloride (100 ml), and adamantane (13.6 g, 0.10 mole), and the mixture is cooled to 15-20° with rapid stirring in an ice bath. One milliliter of 98% formic acid is added and the mixture is stirred until the evolution of carbon monoxide is rapid (about 5 minutes). A solution of 29.6 g (38 ml, 0.40 mole) of t-butyl alcohol in 55 g (1.2 mole) of 98-100% formic acid is then added dropwise to the stirred mixture over 1-2 hours, the temperature being maintained at 15-20°. After stirring for an additional 30 minutes, the mixture is poured onto 700 g of ice, the layers are separated, and the aqueous (upper) layer is extracted three times with lOO-ml portions of carbon tetrachloride. The combined carbon tetrachloride solutions are shaken with 110 ml of 15 A ammonium hydroxide, whereupon ammonium 1-adamantanecarboxylate forms as a crystalline solid. This precipitate is collected by filtration through a fritted glass funnel and washed... 

A stirred reactor contains a batch of 700 kg reactants of specific heat 3.8 kJ/kg K initially at 290 K, which is heated by dry saturated steam at 170 kN/m2 fed to a helical coil. During the heating period the steam supply rate is constant at 0.1 kg/s and condensate leaves at the temperature of the steam. If heat losses arc neglected, calculate the true temperature of the reactants when a thermometer immersed in the material reads 360 K. The bulb of the thermometer is approximately cylindrical and is 100 mm long by 10 mm diameter with a water equivalent of 15 g, and the overall heat transfer coefficient to the thermometer is 300 W/m2 K. What would a thermometer with a similar bulb of half the length and half the heat capacity indicate under these conditions ... 

Acetylcyclohexanone. Method A. Place a mixture of 24-6 g. of cyclohexanone (regenerated from the bisulphite compound) and 61 g. (47 5 ml.) of A.R. acetic anhydride in a 500 ml. three-necked flask, fitted with an efficient sealed stirrer, a gas inlet tube reaching to within 1-2 cm. of the surface of the liquid combined with a thermometer immersed in the liquid (compare Fig. II, 7, 12, 6), and (in the third neck) a gas outlet tube leading to an alkali or water trap (Fig. II, 8, 1). Immerse the flask in a bath of Dry Ice - acetone, stir the mixture vigorously and pass commercial boron trifluoride (via an empty wash bottle and then through 95 per cent, sulphuric acid) as fast as possible (10-20 minutes) until the mixture, kept at 0-10°, is saturated (copious evolution of white fumes when the outlet tube is disconnected from the trap). Replace the Dry Ice-acetone bath by an ice bath and pass the gas in at a slower rate to ensure maximum absorption. Stir for 3 6 hours whilst allowing the ice bath to attain room temperature slowly. Pour the reaction mixture into a solution of 136 g. of hydrated sodium acetate in 250 ml. of water, reflux for 60 minutes (or until the boron fluoride complexes are hydrolysed), cool in ice and extract with three 50 ml. portions of petroleum ether, b.p. 40-60° (1), wash the combined extracts free of acid with sodium bicarbonate solution, dry over anhydrous calcium sulphate, remove the solvent by... 

A mixture of 5 g. of anhydrous zinc chloride (Note 1) and 280 g. (2.00 moles) of 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid /9-lac-tone 2 is placed in a 500-ml. three-necked flask equipped with a sealed stirrer (Note 2), a coarse fritted-glass gas-dispersion thimble, a thermometer immersed in the liquid, and an air-cooled reflux condenser (Note 3). The outlet of the condenser is connected to a bubble counter filled with concentrated sulfuric acid this in turn is vented to the atmosphere through a water scrubber. The flask is immersed in an ice bath, and stirring is started. When the temperature of the mixture is about 10°, anhydrous hydrogen chloride is introduced through the gas-dispersion tube... 

The crude enamine is dissolved in 450 ml. of ether, and the solution is transferred to a 1-1. three-necked flask equipped with a sealed stirrer, a 250-ml. dropping funnel, and a two-necked adapter fitted with a calcium chloride tube and a thermometer immersed in the solution. A solution of 71-76 g. (0.85-0.90 mole) (Note 5) of methyl propiolate (Caution Methyl propiolate is a severe lachrymator and should he handled only in the hood.) in 150 ml. of ether is added dropwise. During the addition the temperature of the mixture is maintained at 25-30° by periodic cooling of the reaction flask in a dry ice-acetone bath. When the addition is almost complete, a white solid begins to separate. The mixture is stirred at 25-30° for an additional hour, cooled to 0°, and filtered to remove the solid. This is dissolved in 700 ml. of 6% hydrochloric acid (Note 6), the acidic solution is warmed at 55-60° for 1 hour, and the mixture is cooled and extracted with two 100-ml. portions of ether. The ether is removed on a steam bath, and the residue of crude methyl 10-oxocyclodec-2-ene-l-carboxylate is dissolved in 300 ml. of methanol and hydrogenated over 5 g. of 5% palladium-on-alumina catalyst at 40 p.s.i. pressure and room temperature. 

Nitromethane. 103 cc of 40% sodium hydroxide solution is added, slowly with stirring, to a mixture of 100 g of chloroacetic acid and 100 g of crushed ice until the mixture is just barely alkaline to phenolphthalein. Keep the temp between 10-20° during this addition. 73 g of sodium nitrite in 100 cc of water is added and the whole is heated in a 500 cc flask, rigged to a distillation apparatus that has the thermometer immersed in the liquid. Distillation of nitromethane starts at about 87° and continues to come over to 108-110°, which is where the temp is maintained for 30 min. Nitromethane is separated from the aqueous layer of the distillate in a separation funnel and is distilled three more times, being separated from the aqueous layer after each distillation. The nitro is then dried over calcium chloride and distilled again, collecting the fraction boiling at 98-101°. Yield 27 g. 

Temperatures below 12°C are not usually used, since crystallization of nitroglycerine could take place. Lower temperatures (e.g. 5-7°C) can be applied only when a mixture of glycerine with glycol or diglycerol is nitrated and if there exists no fear that the mixture of esters resulting from the reaction can freeze. In factory practice, nitration is performed mainly at temperatures of about 20-25°C or at 25-30°C. The temperature is measured by means of at least two thermometers, immersed in the vessel at different depths. 

The condensation reaction was carried out in a stirred 50 cm3 glass flask under a reflux condition. The reaction temperature was maintained by a heated silicon oil bath surrounding the reactor, and measured by a mercury thermometer immersed into the reaction mixture. After the reaction, the solid product and catalyst were separated from the reaction solution by filtration. The product was dissolved in ethyl acetate and separated from the catalyst particles by another filtration. The product was washed by water and then dried over MgS04. Analysis of the product was made with a 1IPLC (Waters 990) equipped with a —Porasil column. A 30% ethyl acetate in hexane was used as an eluent. The conversion of IICHO, the limiting reactant, was calculated from the isolated solid product. The selectivity was calculated by comparing the peak area of the main product with that for an authentic 4,4 —MDU sample. 

High temperatures may be obtained also with the aid of baths of fusible metal alloys, e.g. Woods metal - 4 parts of Bi, 2 parts of Pb, 1 part of Sn and 1 part of Cu - melts at 71 °C Rose s metal - 2 of Bi, 1 of Pb and 1 of Sn - has a melting point of 94 °C a eutectic mixture of lead and tin, composed of 37 parts of Pb and 63 parts of Sn, melts at 183 °C. Metal baths should not be used at temperatures much in excess of 350 °C owing to the rapid oxidation of the alloy. They have the advantage that they do not smoke or catch fire they are, however, solid at ordinary temperature and are usually too expensive for general use. It must be remembered that flasks or thermometers immersed in the molten metal must be removed before the metal is allowed to solidify. 

Total immersion means standardization with the thermometer immersed to the top of the mercury column, with the remainder of the stem and the upper expansion chamber exposed to the ambient temperature. Partial immersion means standardization with the thermometer immersed to the indicated immersion line etched on the front of the thermometer, with the remainder of the stem exposed to the ambient temperature. If used under any other condition of immersion, an emergent-stem correction is necessary to obtain correct temperature readings. 

Temperature measured by a (dry) thermometer immersed in vapor-gas mixture. 

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