Higher-boiling products

Production of p-xylene via p-xylene removal, i.e., by crystallization or adsorption, and re-equilibration of the para-depleted stream requires recycle operation. Ethylbenzene in the feed must therefore be converted to lower or higher boiling products during the xylene isomerization step, otherwise it would build up in the recycle stream. With dual-functional catalysts, ethylbenzene is converted partly to xylenes and is partly hydrocracked. With mono-functional acid ZSM-5, ethylbenzene is converted at low temperature via transalkylation, and at higher temperature via transalkylation and dealkylation. In both cases, benzene of nitration grade purity is produced as a valuable by-product. 

Petroleum group analyses are conducted to determine amounts of the petroleum compound classes (e.g., saturates, aromatics, and polars/resins) present in petroleum-contaminated samples. This type of measurement is sometimes used to identify fuel type or to track plumes. It may be particularly useful for higher-boiling products such as asphalt. Group-type test methods include multidimensional gas chromatography (not often used for environmental samples), high-performance... 

In the production of chloroprene from butadiene, there are three essential steps liquid- or vapour-phase chlorination of butadiene to a mixture of 3,4-dichloro-l-butene and l,4-dichloro-2-butene catalytic isomerization of 1,4-dichloro-2-butene to 3,4-dichloro-l-butene and caustic dehydrochlorination of the 3,4-dichloro-l-butene to chloroprene. By-products in the first step include hydrochloric acid, 1-chloro-1,3-butadiene, trichlorobutenes and tetrachlorobutanes, butadiene dimer and higher-boiling products. In the second step, the mixture of l,4-dichloro-2-butene and 3,4-dichloro-l-butene isolated by distillation is isomerized to pure 3,4-dichloro-l-butene by heating to temperatures of 60-120°C in the presence of a catalyst. Finally, dehydrochlorination of 3,4-dichloro-l-butene with dilute sodium hydroxide in the presence of inhibitors gives crude chloroprene (Kleinschmidt, 1986 Stewart, 1993 DuPont Dow Elastomers, 1997). 

Acid-catalysis was demonstrated for the addition of phenol to epichlorohydrin by Levas and Lefebre,1 1 using boron trifluoride. Although some unidentified higher-boiling products accompanied the desired adduct, this procedure was deemed superior to that reported by Boyd and Marie 8 under alkaline conditions, which requires as much as 6 weeks for completion. Bradley and co-workers M have objected, on the other hand, that the boron trifluoride-catalyged process involves an excessively large phenol epichlorohydrin ratio and is therefore uneconomical. 

H. Boer, P. van Arkel and W. J. Boersma, An automatic paraffins-naphthenes-aromatics (PNA), analyzer for the under 200 °C fraction contained in a higher boiling product ,... 

In particular, we will emphasize (1) total liquid yield, including pentanes and all of the higher boiling product, and (2) octane number of the light product consisting mainly of molecules with carbon numbers of 5 and 6, referred to as C5-l80°F product. High C5+... 

Our previous studies with model compound solvents indicated that higher boiling products can be produced via dimerization by coupling of aromatic methyl groups and by alkylation of the solvent by light coal fragments. 

The activity of acid-type catalysts for polymerization of olefins to higher boiling product has long been known, as reviewed by Oblad et al. (1). Depending on reaction conditions, the product can be predominantly olefinic, or a mixture of olefins, paraffins, naphthenes and aromatics ("conjunct" polymerization). 

The higher-boiling products obtained in the hydrogen chloride-promoted reaction consisted chiefly of... 

As is apparent from the results summarized in Table 1, both hydrochloric acid (dilute or concentrated) and anhydrous hydrogen chloride were effective in greatly increasing the ratios of ethylcyclohexane to higher-boiling product. 

Liquid Alkanes. The peroxide-induced reaction of ethylene with a molar excess of n-pentane in the presence of hydrochloric acid produced heptanes in 27% yield together with only a relatively small amount of higher-boiling product (Expt. 10, Table II). The chief heptane was 3-methylhexane ( which was obtained in more than three times the quantity of 3-ethylpentane (4). 

The reaction of isopentane with ethylene under the same conditions as those used for n -pentane resulted in about the same yield of heptanes (31%) and a very small amount of higher-boiling product (Expt. 11). The heptanes consisted of more than 6.5 times as much 3,3-dimethylpentane as 2,3-dimethylpentane. It may be concluded that abstraction of the single hydrogen attertiary carbon atom takes place much more readily than does abstraction of one of the two hydrogen atoms attached to the secondary (penultimate) carbon atoms. 

Vinylation Studies in the Absence of Copper(II). Our results obtained with various systems in the absence of cupric salts—i.c., a one-pass reaction of palladium (II), are given in Table I. No higher boiling products were obtained than hexenyl acetates. This agrees with Henry (20), who reports that in this system (Pd (II), HOAc, NaOAc) cupric ion is necessary for forming higher boiling products. 

The separation of the Rh-distearylamine-TPPTS catalyst system by membranes was tested on pilot plant scale with crude aldehyde from the hydroformylation of DCP. Figure 2 shows the principle of the membrane separation step. Within the module, the mixture of crude oxoaldehyde, toluene, free ligands, and the Rh catalyst complex coming from the reactor is parallel- pumped to the surface of the membrane. Only aldehyde and higher-boiling products pass through the membrane. The concentrate of Rh complex and ligands is recycled back to the reactor. 

An alternative workup, suitable for higher boiling products, involves quenching the reaction with water, drying, removal of the solvent and distillation. ... 

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