Atmospheric pressure distillation

Pressure distillation Atmospheric pressure distillation Vacuum distillation... 

Pressure (distillation Atmospheric pressure (distillation Vacuum (distillation 0.5Q2 0.3Q2 0.15D Branan, C. R., The Process Engineer s Pocket Handbook, Vol. 1, Gulf Publishing Co., 1976. 

High-boiling hydrocarbon fractions (heavy residues) used as feedstock for petroleum (xikc are residues from distillation (atmospheric pressure, vacuum) or cracking (e.g. thermal. 

Commercial equipment is available which automatically switches from atmospheric distillation to vacuum distillation and calculates the distillation curve as temperatures under atmospheric pressure conditions as a function of weight or volume per cent recovery. 

The results are presented as a distillation curve showing the boiling temperature (corrected to atmospheric pressure) as a function of the distilled volume. 

Conversion of the Low Pressure Distillation Results into Equivalent Results for Atmospheric Pressure... 

To convert low pressure distillation results into those of atmospheric pressure, the Maxwell and Bonnel (1955) equations are used. 

Crude oil is generally characterized by a TBP analysis whose results are expressed as temperatures equivalent to atmospheric pressure as a function of the fraction of volume and weight distilled... 

The flash curve at atmospheric pressure can be estimated using the results of the ASTM D 86 distillation by a correlation proposed by the API. For the same volume fraction distilled one has the following relation ... 

Certain curves, T = f(% distilled), level off at high temperatures due to the change in pressure and to the utilization of charts for converting temperatures under reduced pressure to equivalent temperatures under atmospheric pressure. 

Distillation under Reduced Pressure. Occasionally a liquid, when distillation is attempted under atmospheric pressure, will undergo partial or complete decomposition before its boiling-point is reached. To overcome this difficulty, the liquid is distilled under reduced pressure, so that its boiling-point shall be definitely below its thermal decomposition point. 

Chill the concentrated solution of the amine hydrochloride in ice-water, and then cautiously with stirring add an excess of 20% aqueous sodium hydroxide solution to liberate the amine. Pour the mixture into a separating-funnel, and rinse out the flask or basin with ether into the funnel. Extract the mixture twice with ether (2 X25 ml.). Dry the united ether extracts over flake or powdered sodium hydroxide, preferably overnight. Distil the dry filtered extract from an apparatus similar to that used for the oxime when the ether has been removed, distil the amine slowly under water-pump pressure, using a capillary tube having a soda-lime guard - tube to ensure that only dry air free from carbon dioxide passes through the liquid. Collect the amine, b.p. 59-61°/12 mm. at atmospheric pressure it has b.p. 163-164°. Yield, 18 g. 

Cool the solution thoroughly in ice-water, and then make it alkaline by the cautious addition (with stirring or shaking) of a solution of 80 g. of sodium hydroxide in ca, 150 ml. of water. Now isolate the free tertiary amine by steam-distillation into hydrochloric acid, etc., precisely as for the primary amine in Stage (D), but preferably using a smaller flask for the final distillation. Collect the 2-dimethylamino- -octane, b.p. 76-78715 mm. Yield, 13-14 g. At atmospheric pressure the amine has b.p. 187-188°. 

If a vacuum-distillation apparatus is not available for the above preparation, the crude product may be distilled at atmospheric pressure and the acetoacetate collected as the fraction boiling at i75 -i85 . A pure preparation cannot be obtained in this way, however, because the ester decomposes slightly when distilled at atmospheric pressure. 

For distillations conducted at atmospheric pressure, the barometric pressures are rarely exactly 760 mm. and deviations may be as high as 20 mm. To correct the observed boiling point to normal pressiu e (760 mm.), the following approximate expression may be used ... 

Rubber stoppers are frequently employed in the laboratory in vacuum distiUation assemblies (compare Section 11,19) for distillations under atmospheric pressure bark corks are generally used. Many organic liquids and vapours dissolve new rubber stoppers slightly and cause them to swell. In practice, it is found that rubber stoppers which have been previously used on one or two occasions are not appreciably attacked by most organic solvents, owing presumably... 

Many organic substances cannot be distilled satisfactorily under atmospheric pressure because they undergo partial or complete decom-... 

Receiver adapters or connectors. Various forms of receiver adapters are shown in Figs. 11, 56, 26-29. The simplest form. Fig. 11, 56, 26, carries a glass hook for securing it to the condenser by means of a rubber band from the side tube to the hook an improved form, incorporating two ground glass joints is shown in Fig. 11, 56, 27. A useful adapter is illustrated in Fig. 11, 56, 28 when employed at atmospheric pressure, a drying tube may be attached to the side tube, if desired in a distillation under reduced pressure, the side tube is connected to the pump. Fig. 11, 56, 29 depicts a receiver adapter with an additional socket connection. 

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°. 

With higher aliphatic acids, RCOOH, keten yields first a mixed anhydride CH3COOCOR, which can be distilled under reduced pressure by slow distillation at atmospheric pressure the mixed anhydride undergoes rearrangement into the anhydride of the higher fatty acid and acetic acid, for example ... 

Diethyl oxalate. Reflux a mixture of 45 g. of anhydrous oxalic acid (1), 81 g. (102-5 ml.) of absolute ethyl alcohol, 190 ml. of sodium-dried benzene and 30 g. (16-5 ml.) of concentrated sulphuric acid for 24 hours. Work up as for Diethyl Adipate and extract the aqueous laj er with ether distil under atmospheric pressure. The yield of ethyl oxalate, b.p. 182-183°, is 57 g. 

Commercial 2 4-dichlorophenoxyacetic acid may be recrystallised from benzene m.p. 139-140°. Reflux 10 g. of the acid with 15 ml. of thionyl chloride on a steam bath for 1 hour, distil off the excess of thionyl chloride at atmospheric pressure and the residue under reduced pressure 2 4-dichlorophenoxyacetyl chloride (8 g.) passes over at 155-157°/22-23 mm. It occasionally crystallises (m.p. 44-5-45-5°), but usually tends to remain as a supercooled liquid. 

Maleic acid may be prepared by warming malic acid with acetyl chloride, distilling the mixture under atmospheric pressure to isolate maleic anhydride, and hydrolysing the latter by boding with water. 

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