Petroleum light

The Reid vapor pressure characterizes the light petroleum products it is measured by a standard test (refer to Chapter 7) which can be easily simulated. 

Petroleum solvents are relatively light petroleum cuts, in the C4 to C14 range, and have numerous applications in industry and agriculture. Their use is often related to their tendency to evaporate consequently, they are classified as a function of their boiling points. 

If possible, this can be done by building a 1 1 mock-up of the measuring position, using the same pipe dimensions and material as in the process part. The mock-up should then be filled with a suitable liquid, in this case gasoline or light petroleum, to which a precisely measured amount of tracer is added. This way, the response towards a known dilution of the tracer can be found. 

Petroleum Available in fractions of b.p. 40-60°, 60-80°, 80-100°, 100-120° yy Frequently called light petroleum or petrol ether. Unless specially purified, contains sulphur derivatives, etc.y as impurities. 

Selection of solvents. The choice of solvent will naturally depend in the first place upon the solubility relations of the substance. If this is already in solution, for example, as an extract, it is usually evaporated to dryness under reduced pressure and then dissolved in a suitable medium the solution must be dilute since crystallisation in the column must be avoided. The solvents generally employed possess boiling points between 40° and 85°. The most widely used medium is light petroleum (b.p. not above 80°) others are cycZohexane, carbon disulphide, benzene, chloroform, carbon tetrachloride, methylene chloride, ethyl acetate, ethyl alcohol, acetone, ether and acetic acid. 

The developer is generally a solvent in which the components of the mixture are not too soluble and is usually a solvent of low molecular weight. The adsorbent is selected so that the solvent is adsorbed somewhat but not too strongly if the solvent is adsorbed to some extent, it helps to ensure that the components of the mixture to be adsorbed will not be too firmly bound. Usually an adsorbate adheres to any one adsorbent more firmly in a less polar solvent, consequently when, as frequently occurs, a single dense adsorption zone is obtained with light petroleum and develops only slowly when washed with this solvent, the development may be accelerated by passing to a more polar solvent. Numerous adsorbat are broken up by methyl alcohol, ethyl alcohol or acetone. It is not generally necessary to employ the pure alcohol the addition from 0 5 to 2 per cent, to the solvent actually used suffices in most cases. 

The acid chloride is available commercially, but it is more economical to prepare it from the acid as and when required. Furthermore, 3 5-dini-trobenzoyl chloride tends to undergo hydrolysis if kept for long periods, particularly if the stock bottle is frequently opened. The substance may, however, be stored under light petroleum. 

The melting points of these esters are usually much lower than those of the corresponding 3 5 dinitrobenzoates their preparation, therefore, offers no advantages over the latter except for alcohols of high molecular weight and for polyhydroxy compounds. The reagent is, however, cheaper than 3 5 dinitrobenzoyl chloride it hydrolyses in the air so that it should either be stored under light petroleum or be prepared from the acid, when required, by the thionyl chloride or phosphorus pentachloride method. 

Dissolve 5 g. of hydroxylamine hydrochloride in 10 ml. of water in a small conical flask and add a solution of 3 g. of sodium hydroxide in 10 ml. of water. Cool the solution in cold or ice water, and add 6 g. (7-6 ml.) of acetone slowly. Cool the flask, shake well, and leave overnight, during which time the oxime may crystallise out. If no crystals appear, cork the flask and shake vigorously when the acetoxime usually separates as colourless crystals. Filter the crystals at the pump, dry rapidly between filter paper (yield 2- 6 g.) and determine the m.p. (59°). Extract the filtrate with two 20 ml. portions of ether, and remove the solvent a further 0 - 5 g. of acetoxime (m.p. 60°) is obtained. Recrystallise from light petroleum, b.p. 40-60° CAUTION inflammable) to obtain the pure acetoxime, m.p. 60°. Acetoxime sublimes when left exposed to the air. 

Dissolve 2 5 g. of hydroxylamine hydrochloride and 4 g. of crystallised sodium acetate in 10 ml. of water in a small flask or in a test-tube. Warm the solution to about 40° and add 2 5 g. of cyclohexanone. Stopper the vessel securely with a cork and shake vigorously for a few minutes the oxime soon separates as a crystalline solid. Cool in ice, filter the crystals at the pump, and wash with a little cold water. RecrystaUise from light petroleum, b.p. 60-80°, and dry the crystals upon filter paper in the air. The yield of pure cycZohexanone oxime, m.p. 90°, is 2 -5 g. 

For water insoluble aldehydes or ketones, the following alternative procedure may be used. Reflux a mixture of 0-6 g. of the aldehyde or ketone, 0 5 g. of hydroxylamine hydrochloride, 5 ml. of ethanol and 0 5 ml. of pyridine on a water bath for 15-60 minutes. Remove the alcohol either by distillation (water bath) or by evaporation of the hot solution in a stream of air (water pump). Add 5 ml. of water to the cooled residue, cool in an ice bath and stir until the oxime crystallises Filter off the solid, wash it with a little water and dry. Recrystallise from alcohol (95 per cent, or more dilute), benzene, or benzene - light petroleum (b.p. 60-80°). 

Anilides. Dilute the acid chloride with 5 ml. of pure ether (or benzene), and add a solution of 2 g. of pure aniline in 15-20 ml. of the same solvent until the odour of the acid chloride has disappeared excess of aniline is not harmful. Shake with excess of dilute hydrochloric acid to remove aniline and its salts, wash the ethereal (or benzene) layer with 3-5 ml. of water, and evaporate the solvent [CAUTION ] Recrystallise the anilide from water, dilute alcohol or benzene - light petroleum (b.p. 60-80°). 

Alternatively, mix equal amounts (say, 0-2 g. of each) of the amine and phenyl isothiocyanate in a test-tube and shake for 2 minutes. If no reaction occurs, heat the mixture gently for 2 minutes and then cool in ice until the mass soUdifies. Powder the soUd, wash it with a little light petroleum (b.p. 100-120°), and recrystallise from rectified spirit. 

Method 1. Place in a test-tube or small flask 1-3 g. of glycerol and 30 ml. of 10 per cent, sodium hydroxide solution add gradually, with simultaneous shaking, 1-2 g. of benzoyl chloride. Stopper the vessel, shake for several minutes and allow to stand. Decant the solution from the pasty solid and wash the latter with cold water by decantation. Recrystallise the solid tribenzoate from dilute rectified (or methylated) spirit or from light petroleum, b.p. 40-60° the pure compound has m.p. 76°. 

To obtain maleic acid, evaporate the maleic anhydride with one half of its weight of water on a water bath remove the last traces of water by leaving in a desiccator over concentrated sulphuric acid. The resulting maleic acid has m.p. 143° and is quite pure (1). It may be recrystaUised, if desired, from acetone- light petroleum (b.p. 60-80°) and then melts at 144° (1). 

Mix together in a 250 ml. flask carrying a reflux condenser and a calcium chloride drying tube 25 g. (32 ml.) of freshly-distilled acetaldehyde with a solution of 59-5 g. of dry, powdered malonic acid (Section 111,157) in 67 g. (68-5 ml.) of dry pyridine to which 0-5 ml. of piperidine has been added. Leave in an ice chest or refrigerator for 24 hours. Warm the mixture on a steam bath until the evolution of carbon dioxide ceases. Cool in ice, add 60 ml. of 1 1 sulphuric acid (by volume) and leave in the ice bath for 3-4 hours. Collect the crude crotonic acid (ca. 27 g.) which has separated by suction filtration. Extract the mother liquor with three 25 ml. portions of ether, dry the ethereal extract, and evaporate the ether the residual crude acid weighs 6 g. Recrystallise from light petroleum, b.p. 60-80° the yield of erude crotonic acid, m.p. 72°, is 20 g. 

Use 01 g. of the platinum oxide catalyst and 11 4 g, of pure cinnamic acid dissolved in 100 ml. of absolute alcohol. The theoretical volume of hydrogen is absorbed after 7-8 hours. Filter off the platinum, and evaporate the filtrate on a water bath. The resulting oil solidifies on cooling to a colourless acid, m.p. 47-48° (11-2 g.). Upon recrystallisation from light petroleum, b.p. 60-80°, pure dihydrocinnamic acid, m.p. 48-49°, is obtained. 

An alternative procedure is to leave the syrupy residue in a vacuum desiccator over anhydrous calcium chloride and siUca gel, and to Alter ofl the successive Crops of crystals as they separate. These are washed with light petroleum, b.p. 40-60°, spread on a porous tile and recrystallised. 

The following is a modification of the process described and gives quite satisfactory results. Wash the crude mixture of benzonitrile and dibromopentane with sodium carbonate solution until the latter remains alkaline, and then with water. Distil it under reduced pressure and collect the fraction boiling up to 120°/18 mm. Dissolve this in twice its volume of light petroleum, b.p. 40-60°, which has previously been shaken with small volumes of concentrated sulphuric acid until the acid remains colourless. Shake the solution with 6 per cent, of its volume of concentrated sulphuric acid, allow to settle, and run ofi the sulphuric acid layer repeat the extraction until the acid is colourless or almost colourless. Wash successively with water, sodium carbonate solution and water, dry over anhydrous calcium chloride or calcium sulphate, and distil off the solvent. Distil the residue under diminished pressure and collect the 1 6-dibromopentane at 98- 100°/13 mm. 

The inactive aec.-octyl hydrogen phthalate may be recrystallised from light petroleum, b.p. 60-80°, or from glacial acetic acid, and then melts at 55°. 

Procedure 1. Dissolve 1 g. of the compound in 5 ml. of chloroform in a test-tube and cool in ice. Add 5 ml. of chlorosulphonic acid CA UTION in handhng) dropwise and with shaking. When the initial evolution of hydrogen chloride subsides, remove the reaction mixture from the ice and, after 20 minutes, pour it into a 50 ml. beaker filled with crushed ice. Separate the chloroform layer, wash it well with water, and evaporate the solvent. Recrystallise the residual aryl sulphonyl chloride from light petroleum (b.p. 40-60°), chloroform or benzene this is not essential for conversion into the sulphonamide. 

The experimental details for mono-M-propylanillne are as follows. Reflux a mixture of 230 g. of aniline and 123 g. of n-propyl bromide for 8-10 hours. Allow to cool, render the mixture alkafine, and add a solution of 150 g. of zinc chloride in 150 g. of water. Cool the mixture and stir after 12 hours, filter at the pump and drain well. Extract the thick paste several times with boiling light petroleum, b.p. 60-80° (it is best to use a Soxhlet apparatus), wash the combined extracts successively with water and dilute ammonia solution, and then dry over anhydrous potassium carbonate or anhydrous magnesium sulphate. Remove the solvent on a water bath, and distil the residue from a Claisen flask with fractionating side arm (well lagged). Collect the n-propyl-aniline at 218-220° the yield is 80 g. Treat the pasty solid zincichloride with an excess of. sodium hydroxide solution and steam distil 130 g. of pure aniline are recovered. 

About 200 ml. of light petroleum is required for recrystallisation. It is therefore advisable, for the sake of economy when the preparation is conducted by a large class of students, that onl about I g. of the crude material be recrystallised from this solvent. The crude compound may be employed in the preparation of p-amino-azobonzene. 

Into a 1-litre beaker, provided with a mechanical stirrer, place 36 - 8 g. (36 ml.) of aniline, 50 g. of sodium bicarbonate and 350 ml. of water cool to 12-15° by the addition of a little crushed ice. Stir the mixture, and introduce 85 g. of powdered, resublimed iodine in portions of 5-6 g, at intervals of 2-3 minutes so that all the iodine is added during 30 minutes. Continue stirring for 20-30 minutes, by which time the colour of the free iodine in the solution has practically disappeared and the reaction is complete. Filter the crude p-iodoaniline with suction on a Buchner funnel, drain as completely as possible, and dry it in the air. Save the filtrate for the recovery of the iodine (1). Place the crude product in a 750 ml. round-bottomed flask fitted with a reflux double surface condenser add 325 ml. of light petroleum, b.p. 60-80°, and heat in a water bath maintained at 75-80°. Shake the flask frequently and after about 15 minutes, slowly decant the clear hot solution into a beaker set in a freezing mixture of ice and salt, and stir constantly. The p-iodoaniline crystallises almost immediately in almost colourless needles filter and dry the crystals in the air. Return the filtrate to the flask for use in a second extraction as before (2). The yield of p-iodoaniline, m.p. 62-63°, is 60 g. 

Two extractions usually sufiSce, but if much organic material remains, a third extraction should be made. If the p-iodoaniline from the second and third extractions is coloured, it should be refluxed for a short period in light petroleum solution with a little decolourising carbon and filtered through a hot water funnel (CA U TION inflammable). 

If the benzoyl derivative is soluble in alkali, precipitate it together with the benzoic acid derived from the reagent by the addition of hydrochloric acid filter and extract the product with cold ether or light petroleum (b.p. 40-60°) to remove the benzoic acid. 

Reflux 0-5 g. of the amine with 5 ml. of 90 per cent, formic acid (CAUTION in handling) for 10 minutes, and dilute the hot solution with 10 ml. of cold water. Cool in ice and, in some cases, saturate with salt if the derivative does not separate immediately. Filter, wash with cold water, and recrystallise from water, alcohol or light petroleum (b.p. 60-80°). 

P-Naphthyl acetate. Dissolve 5 0 g. of p-naphthol in 25 ml. of 10 per cent, sodium hydroxide solution in a 250 ml. reagent bottle, add 60 g. of crushed ice, and 5-7 g. (5 -5 ml.) of acetic anhydride. Shake vigorously for 10-15 minutes the p-naphth acetate separates as colourless crystals. Filter with suction, wash with water, drain and dry in the air. Recrystallise from light petroleum (b.p. 60-80°) or from dilute alcohol. The yield of pure product, m.p. 71°, is 6-5 g. 

Dissolve 0 -5 g. of the phenol in 4-5 ml. of dry p ridine, add 1 - 3 g. of 3 5-dinitrobenzoyl chloride and reflux for 25-30 minutes. Pour the cold reaction mixture into 40 ml. of ca. 2N hydrochloric acid. Decant the supernatant aqueous hquid from the precipitated sohd or oil and stir it vigorously with about 10 ml. of N sodium carbonate solution. Filter off the sohd derivative and wash it with water. RecrystaUise from alcohol, dilute alcohol, benzene - acetone or benzene - light petroleum (b.p. 60-80 ),... 

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