Xylene crude

The water content of crude oils is determined by a standardized method whose procedure is to cause the water to form an azeotrope with an aromatic (generally industrial xylene). Brought to ambient temperature, this azeotrope separates into two phases water and xylene. The volume of water is then measured and compared with the total volume of treated crude. 

Initial portion of the TBP curve of a Saharan crude oil (Note the discontinuities due to the presence of aromatics benzene B, toluene T, xylenes X). 

A mixture of 100 g of 5,5-dimethylacridan, 20 g of pulyerized sodium amide and 6.5 g of 1 -chloro-3-dimethylaminopropane in 50 ml of xylene is heated at reflux with stirring for one hour. To the cooled reaction mixture is added one yolume of water. The organic layer is separated and extracted several times with diluted lactic acid. The acidic extracts are combined, washed with ether and neutralized by alkali. The crude 10-(3 -dimethylaminopropvl)-5,5-dimethylacridan is isolated by ether extraction and purified by distillation in a high vacuum. The yield is 6,4 g BP 170°-1 B0°C/0.005 mm. n = 1.5990. 

A mixture of 40.5 g (0.15 mol) of 3-carbethoxy-4-hydroxy-2-methyl-2H-1.2-benzothiazine 1,1 -dioxide, 20.6 g (0.21 mol) of 3-amino-5-methylisoxazole, and 2,500 ml of xylene was refluxed for 24 hours in a Soxhiet apparatus, the thimble of which contained 60 g of Linde type 4A molecular sieve. The mixture was cooled to 25°C and the resulting crystalline precipitate was collected and washed with ether to give 44 g of crude product. Recrystallization from 1,6(X) ml of 1,4-dioxan gave 34.7 g of material, MP 265°C to 271°C dec. 

A solution of 3-dimethylsulfamoylphenthiazine (5 g) in anhydrous xylene (100 cc) is heated under reflux for 1 hour with sodamide (0.67 g). 3-(4-methyl-1-piperazinyl)-1 heated under reflux for 5 hours. After treatment of the reaction products, a crude oily base (2.5 g) is obtained after treatment. By the addition of a solution of fumaric acid in ethanol to an ethanolic solution of the base, 3-dimethylsulfamoyl-10-(3-4 -methyl-1 -piperazinylpropyD-phenthiazine diacid fumarate (2.6 g) is obtained, melting point 182°C. The base recrystallized from ethyl acetate melts at about 140°C. 

A suspension of NaOEt, prepared by adding EtOH (2 rnL) to a suspension of xylene-washed Na (0.77 g, 33.5 mmol) in anhyd Et20 (90 mL), was added to a solution of diethyl 4-(chloromethyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate (1 10 g, 33 mmol) in anhyd El20 (600 mL) whereupon afine precipitate appeared immediately. The mixture was stirred and heated under reflux for 18 h, then cooled, and the precipitate of NaCl was removed by filtration. The volume of the filtrate was reduced to 100 mL, and the filtrate was washed with cold H20, then dried (MgS04). The Et2C) was evaporated under reduced pressure to yield the crude product as a golden oil [yield 7.3 g (83%)] which was purified by distillation bp 142-145 C/0.1 Torr. 

Method A To a mixture of the 9-(hydroxymethyl)-9,10-dihydroacridine (4mmol) and sea sand (10g) under N2 in refluxing anhyd xylene (30 mL) was added in four portions during a 2-h period, P205 (4g, 28 mmol). The yellow-orange mixture was heated under reflux for an additional 1.5 h, then cooled, and quenched cautiously with a large excess of cold H20. The mixture was filtered to remove the sand, and the aqueous layer was then separated from the filtrate. The sand and the aqueous layer were extracted with hot benzene and the benzene and xylene solutions were combined, dried, and the solvent removed under reduced pressure. The crude product was obtained as a yellow-orange residue which was purified by crystallization (benzene). 

C. MEDINA. The crude methylenedi(nitro-formamide) is pressed dry on the filter, stirred into lOSml of formic acid, and the paste allowed to stand overnight. The next day the soln is filtered thru an acid-proof flit, the formic acid and w removed by codistn with xylene, and the crude MEDINA, which seps as a sand, filtered and dried over paraffin and NaOH in a vacuum yield 80—100% based on methylene diform-amide, mp 98—103°. The crude MEDINA is recrystd from 2-nitropropane or et chloride iso-Pr ale 9 1, mp 104-059 (Ref 11, p 54). This prepn is also covered in Ref 20... 

Solvent Naphtha (160° benzol). A mixt of small percentages of benzene and toluene with xylene and higher homologs from coal tar. In crude form, a dark straw-colored liq, bp about 160° (80%), d 0.862—0.892g/cc, flash p about 78°F. When refined, a w-white liq, bp about 160° (90%), d 0.862-0.872g/cc, flash p about 78°F. May be obtained from coal tar by fractional distillation. When nitrated, used in Dynamites (Ref 5)... 

Nitrated Solvent Naphtha (N.S.N.). As nitration of crude solvent naphtha by the usual one-stage method results in yields that are too low, because of oxidation, E. Blecher et al (Ref 3) proposed nitrating only the refined material, and in two stages. The two-stage method is described in Colver, pp 255 686—87 (Ref 4). The product consists chiefly of 2,4,6-Trinitro-mesitylene (see under Mesitylene and Deriva- tives in this Vol), and 3,5,6-trinitropseudocumene, with small quantities of the nitrated products of xylene, ethylbenzene, etc... 

Ci2-Ci3 ether carboxylic acid with 4.5-6 mol EO and Ci2-C15 ether carboxylic acid with 9 mol EO as cosurfactant improve the use of alkyl-o-xylene-sulfonate as primary surfactant at different salinity while maintaining good oil solubilization [189]. It is possible to optimize the surfactant system in relation to the crude oil reservoir characteristics. 

Because orr/zo-xylene is more readily isolated and purified (by distillation), it costs less than para-xylene. Like all petrochemicals, prices depend on the price of crude oil but in early 2001, mixed-xylene was about 17 cents/lb while para-xylene was only about 15 cents due to high manufacturing capacity and low demand for use for making terephthalic acid. In the extremely high volumes in which such chemicals are sold, fractions of a penny difference in price can be very important. 

Terephthalic acid (p-TA or TA), a raw material for polyethylene terephthalate (PET) production, is one of the most important chemicals in petrochemical industry. Crude terephthalic acid (CTA), commonly produced by homogeneous liquid phase p-xylene oxidation, contains impurities such as 4-carboxybenzaldehyde (4-CBA, 2000-5000 ppm) and several colored polyaromatics that should be removed to obtain purified terephthalic acid (PTA). PTA is manufactured by hydropurification of CTA over carbon supported palladium catalyst (Pd/C) in current industry [1]. 

An example of this is the commercial process for preparing puru-xylene, the precursor to terephthalic acid, which is polymerised to give polyjethy-lene terephthalate) (PET). In this case, the mixture of xylenes obtained from crude oil is reacted in a zeolite (known as HZSM5). The relative rates of diffusion in and out of the pores are sufficiently different (by a factor of about ten thousand) to allow the extremely efficient and selective conversion of all the isomers to the desired paia isomer, which is the narrowest and can thus move through the structure most rapidly (Figure 4.3). 

The pathways for the degradation of toluene and xylene under denitrifying and sulfate-reducing conditions have been studied most extensively, and they take place by reactions quite different from those used by aerobic bacteria. As an example, two anaerobes affiliated with known sulfate-reducing bacteria isolated from enrichments with crude oil were able to grow at the expense of a number of alkylated benzenes—strain oXySl with toluene, o-xylene, and o-ethyltoluene and strain mXySl with toluene, m-xylene, and m-ethyltoluene (Harms et al. 1999). 

Xylene production Crude oil [resource] Resource depletion 1 1 1... 

The solution is allowed to cool, and the di- -butylamine hydrobromide, which separates in the course of the reaction, is removed by means of a suction filter (Note 2). The filtrate is transferred to a 500-ml. distilling flask, and the xylene is removed by distillation. The crude y-di-w-butylaminopropylphthalimide, a brown oil, is transferred to a 500-ml. round-bottomed flask with a ground-glass joint and treated with 20 ml. of water and 120 ml. of 12 N hydrochloric acid. The flask is fitted with a reflux condenser, and the solution is heated for 6 hours in an oil bath maintained at 140-150°. After the solution has cooled to room temperature, the precipitated phthalic acid is removed by filtration and washed with four 25-ml. portions of cold water. The combined filtrates are transferred to a 600-ml. beaker and heated on a steam bath to evaporate the water and hydrochloric acid. 

The monoaromatic compounds benzene, toluene, ethylbenzene and xylene, commonly found in crude oil, are often jointly called BTEX compounds. The most harmful of these compounds is benzene, which is a known carcinogen. BTEX compounds occur naturally near natural gas and petroleum deposits and are detected in the fumes of forest fires. Most of the highly volatile BTEX compounds released by human activity originate from fuel use and end up as pollutants in the air. Inhaling BTEX-polluted air is also the greatest hazard to humans by these compounds. BTEX compounds are water-soluble, and therefore, improper handling can also cause groundwater contamination. 

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