Benzene distillation

Make a thin paste of 21 5 g. of finely-powdered o-tolidine (a commercial product) with 300 ml. of water in a 1-litre beaker, add 25 g. (21 ml.) of concentrated hydrochloric acid, and warm until dissolved. Cool the solution to 10° with ice, stir mechanically, and add a further 25 g. (21 ml.) of concentrated hydrochloric acid (1) partial separation of o tolidine dihydrochloride will occur. Add a solution of 15 g, of sodium nitrite in 30 ml. of water as rapidly as possible, but keep the temperature below 15° a slight excess of nitrous acid is not harmful in this preparation. Add the clear, orange tetrazonium solution to 175 ml. of 30 per cent, hypophosphorous acid (2), and allow the mixture to stand, loosely stoppered, at room temperature for 16-18 hours. Transfer to a separatory funnel, and remove the upper red oily layer. Extract the aqueous layer with 50 ml, of benzene. Dry the combined upper layer and benzene extract with anhydrous magnesium sulphate, and remove the benzene by distillation (compare Fig. II, 13, 4) from a Widmer or similar flask (Figs. II, 24, 3-5) heat in an oil bath to 150° to ensure the removal of the last traces of benzene. Distil the residue at ca. 3 mm. pressure and a temperature of 155°. Collect the 3 3 -dimethyldiphenyl as a pale yellow liquid at 114-115°/3 mm. raise the bath temperature to about 170° when the temperature of the thermometer in the flask commences to fall. The yield is 14 g. 

B) 40 g of N-chloroacetyl-2-benzylaniline are heated for 2 hours at 120°C together with 50 ml of phosphorus oxychloride and 320 g of polyphosphoric acid. Next the reaction mixture is poured on ice and extracted with benzene. The extract is washed and dried on sodium sulfate and the benzene distilled off. The product obtained (31 g) yields after recrystallization 24 g of 6-chloromethyl-morphanthridine of MP 136° to 137°C. 

If an emulsion has formed, it may be broken by acidifying with hydrochloric acid, whereupon two clear layers are obtained. The benzene solution may be dried and then fractionated or preferably, it may be steam distilled. In the latter case it is transferred to a r-1. Claisen flask, the flask is set in an oil bath (Note 3) and the benzene distilled. Steam is then passed in, and after the last of the benzene is removed, the p-bromodi-phenyl distils with the steam. The temperature of the oil bath is held at 170° in order to hasten the distillation. The product solidifies in the condenser and receiving flask. There is obtained 23-24 g. of -bromodiphenyl which melts at 85-86.5°. 

The crude ester is cooled, an equal volume of benzene is added, then the free acid is neutralized by shaking with about 250 cc. of a 10 per cent solution of sodium carbonate (Note 4). The benzene solution is poured into 1300 cc. of a saturated solution of sodium bisulfite (about 60 g. of technical sodium bisulfite per 100 cc.), contained in a wide-neck bottle equipped with an efficient stirrer, and the mixture stirred for two and a half hours. The mixture soon warms up a little and becomes semi-solid. It is filtered through a 20-cm. Buchner funnel and carefully washed, first with 200 cc. of a saturated solution of sodium bisulfite, finally with two 150-cc. portions of benzene (Notes 5 and 6). The white pearly flakes of the sodium bisulfite addition product are transferred to a 3-I. round-bottom wide-neck flask equipped with a mechanical stirrer and containing 700 cc. of water, 175 cc. of concentrated sulfuric acid, and 500 cc. of benzene. The flask is heated on a steam bath under a hood, the temperature being kept at 55°, and the mixture is stirred for thirty minutes (Note 7). The solution is then poured into a separatory funnel, the benzene separated and the water layer extracted with a 200-cc. portion of benzene. The combined benzene solution is shaken with excess of 10 per cent sodium carbonate solution to remove free acid and sulfur dioxide (Note 8). The benzene is washed with a little water and then dried over anhydrous potassium carbonate (Note 9). The benzene is distilled at ordinary pressure over a free flame from a 500-cc. Claisen flask, the solution being added from a separatory funnel as fast as the benzene distils. It is advisable to distil the ester under reduced pressure although it can be done under ordinary pressure. The fraction distilling around n8°/5mm., 130710 mm., 138715 mm., 148725 mm., 155735 mm., or... 

Alkylation and separation Refining of the hydrogen fluoride Separation of raw LAB and recycled benzene Distillation... 

The major part of the w-amyl benzene distils at 199-201°. A careful fractionation of the distillate that comes over around 75° yields 24 g. (26 per cent of the theoretical amount) of w-butyl chloride boiling at 76-80°. 

The catalytic performances obtained during transalkylation of toluene and 1,2,4-trimethylbenzene at 50 50 wt/wt composition over a single catalyst Pt/Z12 and a dualbed catalyst Pt/Z 121 HB are shown in Table 1. As expected, the presence of Pt tends to catalyze hydrogenation of coke precursors and aromatic species to yield undesirable naphthenes (N6 and N7) side products, such as cyclohexane (CH), methylcyclopentane (MCP), methylcyclohexane (MCH), and dimethylcyclopentane (DMCP), which deteriorates the benzene product purity. The product purity of benzene separated in typical benzene distillation towers, commonly termed as simulated benzene purity , can be estimated from the compositions of reactor effluent, such that [3] ... 

Mix 0.25M substituted benzaldehyde, 0.3M nitroethane, 50 ml dry toluene and 5 ml n-butylamine (or other amine), and reflux 3 hours with a Dean-Stark trap (or prepare the nitro-propene as described elsewhere here). Add 50 g iron powder and 1 g FeCl3 optional) and reflux while adding 90 ml concentrated HCI over 3 hours. Reflux 1 hour more, add 2 liters of water and extract 3 times with ether, then dry and evaporate in vacuum (or steam distill until about 3.5 liters of distillate is obtained extract the distillate 3 times with toluene wash the toluene layers with 7 g NaHS03 in 225 ml of water, then 3 times with water and dry, evaporate in vacuum) to get the ketone. Mix 0.13M ketone, 28 g formamide (or dimethyl-formamide if the N.N-dimethylamine is desired) and 3 ml formic acid and heat at 160°. Add 3 more ml formic acid and heat 16 hours at 170-180° adding formic acid from time to time to keep the pH acid. Distill off the water formed (about 16 ml), cool and extract with 3X70 ml benzene. Distill off the benzene and reflux the residue 7 hours with 30 ml concentrated HCI. Chill, basify with 10% NaOH and extract with 3X70 ml ether. Dry and evaporate the ether in... 

The benzene distillate is yellow and contains some quinone. This, as well as the benzene from the final filtration of the quinone crystals, may be used in a subsequent run and thus raises the yield of the subsequent runs to about 85-90 g. (85-90 per cent of the theoretical amount). 

Triphenylphosphine (100.3 g, 0.3825 mol) and copper(I) chloride (15.14 g, 0.1529 mol) were added to a dry, septum-capped 2 L Schlenk flask and placed under nitrogen. Benzene (distilled and deoxygenated, approximately... 

The submitters used benzene distilled from lithium aluminum hydride, but the checkers used ACS-grade benzene as well as benzene distilled from lithium aluminum hydride, with no significant change in yield. 

The pressure should be reduced gradually and cautiously to avoid the bumping often characteristic of benzene distillations. 

Anhydrous ethyl alcohol is made from the constant boiling mixture with HsO (95 6% ethyl alcohol by weight)—(l)by heating with a substance such as calcium oxide, which reacts with H 0 and not with alcohol, and then distilling, or (21 hv distilling with a volatile liquid, such as benzene [hp 79,6 C). which forms a constam low-boiling mixture with H 0 and alcohol (bp 64.9=C), so that HsO is removed from the main portion of the alcohol after which alcohol plus benzene distills over (bp 78.5°C). Anhydrous ethyl alcohol is required for certain purposes as a solvent and rcagem and fuel applications. 

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