Sulfur styrene mixtures

Of the various chemical modifiers for sulfur which we have examined over the years we must single out the Thiokol family of additives as some of the most effective sulfur modifiers available (10). Unfortunately they are expensive, but their effects are long term. One of the most deceptive of the sulfur additives is styrene monomer (JJ) which is attractive because of its low cost. One can obtain an unusually wide variation of properties in sulfur-styrene mixtures by controlling the degree of reaction. Unfortunately these property modifications are transient, so much so that we use it infrequently and for only some special purpose. The transient characteristics of styrene-sulfur mixtures are attributed to the attack of the polystyryl radicals on the sulfur-sulfur bonds and the rapid opening of the sulfur rings. 

Figure 7. Weight average molecular weight of polystyrene ( x 10 ) from free-radical polymerization of styrene in carbon dioxide + sulfur hexafluoride mixtures. Left. Influence of SF6 content at 56 MPa and 51 °C, 5 hr polymerization time. Right Influence of pressure in the solvent mixture containing 30 % by mass SFe at 51 °C. Pressure dependence of the density (in g/cm ) of the solvent mixture is shown on the right coordinate. [1 MPa = 10 bar],...

The principal use of the alkylation process is the production of high octane aviation and motor gasoline blending stocks by the chemical addition of C2, C3, C4, or C5 olefins or mixtures of these olefins to an iso-paraffin, usually isobutane. Alkylation of benzene with olefins to produce styrene, cumene, and detergent alkylate are petrochemical processes. The alkylation reaction can be promoted by concentrated sulfuric acid, hydrofluoric acid, aluminum chloride, or boron fluoride at low temperatures. Thermal alkylation is possible at high temperatures and very high pressures. 

In a 2-1. round-bottomed flask, fitted with a reflux condenser and mechanical stirrer, are placed 675 g. (8.3 moles) of 37% formalin, 48 g. of sulfuric acid (sp. gr. 1.84), and 312 g. (3 moles) of styrene. The resulting mixture is gently refluxed and stirred for 7 hours. The mixture is cooled, and 500 ml. of benzene is stirred in. The layers are separated, and the aqueous layer is extracted with 500 ml. of benzene. The benzene solutions are combined and washed with two 750-ml. portions of water. The benzene is removed by distillation, and the residual liquid is fractionated under reduced pressure. At 2 mm. pressure a forerun is collected separately, up to a temperature of 96° (Note 1) then the main fraction is collected at 96-103°/2 mm. The yield of 4-phenyl-m-dioxane amounts to 353-436 g. (71-88%) wf 1.5300-1.5311 df 1.092-1.093 (Note 2). 

Insoluble polystyrene crosslinked with divinylbenzene can easily be converted by sulfonation to a usable ion exchanger. For this purpose a mixture of 0.2 g of silver sulfate and 150 ml of concentrated sulfuric acid are heated to 80-90 °C in a 500 ml threenecked flask fitted with stirrer, reflux condenser, and thermometer. 20 g of a bead polymer of styrene and divinylbenzene (see Example 3-41) are then introduced with stirring the temperature climbs spontaneously to 100-105 °C.The mixture is maintained at 100 C for 3 h,then cooled to room temperature and allowed to stand for some hours. Next the contents of the flask are poured into a 11 conical flask that contains about 500 ml of 50% sulfuric acid. After cooling, the mixture is diluted with distilled water, and the gold-brown colored beads are filtered off on a sintered glass filter and washed copiously with water. 

C17H24O, Mr 244.38, mp 35 °C, is a synthetic musk fragrance. It is prepared by Friedel-Crafts acetylation of 1,1,2,3,3,5-hexamethylindane, which can be obtained as a 70 30 mixture with l,l,3,5-tetramethyl-3-ethylindane by reacting a,p-dimethyl-styrene with amylenes or 2-methyl-2-butanol in a mixture of acetic acid and concentrated sulfuric acid [155] ... 

Water (28 g) and polyoxyethylene phenyl ether sulfuric acid ester emulsifier (0.08 g) were added to a 300-ml flask and heated to 85°C while stirring. This solution was then treated with a mixture of the step 4 product (6.3 g), methyl methacrylate (41.6 g), styrene (14 g), butyl acrylate (23.5 g), 2-ethylhexyl acrylate (14.6 g), water (51.6 g), polyoxyethylene phenyl ether sulfuric acid ester emulsifier (6.6 g), and 0.3 g of sodium persulfate over 4 hours. Thereafter, a mixture of water (5.2 g) and ammonium persulfate (0.1 g) were added over 30 minutes and the mixture stirred for an additional 2 hours. It was then cooled to ambient temperature and a white resin isolated, which consisted of 52% solids with a polymerization conversion of 99%. 

Membranes may be manufactured by mixing powdered ion exchange resin with a solution of binder polymer and pouring the heated mixture under pressure onto a plastic mesh or cloth. The concentration of the ion exchanger is normally 50-70%. They are chiefly copolymers of styrene and divinylbenzene, sulfonated with sulfuric acid for introduction of the cation exchange group. 

Concentrated sulfuric acid (0.316 mol) was added over lh to dimethyl sulfide (0.316 mol), the temperature of the reaction mixture being kept below 30°C. Methanol (0.156 mol) was then added over 30 min with the temperature below 35°C. After the mixture had been stirred for 5h, t-BuOH (0.048 mol) was added to it followed by potassium hydroxide (0.58 mol) in 10 equal aliquots over 2.5 h. Benzaldehyde (0.15 mol) was added after the seventh KOH aliquot0 and an alkaline pH had been achieved. The mixture was stirred at room temperature for 12 h and subjected to conventional pentane/aqueous work-up. Styrene oxide was isolated in a 55% yield. 

Hydrazones have also been used as azomethine imine precursors to achieve cycloadditions.157 Proto-nated hydrazones act under suitable conditions as quasi-azomethine imines in polar [3+ + 2] cycloadditions. Thus, r.cetaldehyde phenylhydrazone (201) was found to react with styrene in the presence of sulfuric acid in a regiospecific manner to give pyrazolidine (203 Scheme 47) as a diastereomeric mixture.157 The most commonly used azomethine imine has a phenyl group attached to one end of the dipole and hence has a raised HOMO relative to the unsubstituted system. Because the coefficients at the terminal atoms of the dipole are smaller in the LUMO than they are in the HOMO, the phenyl group does not lower the energy of the LUMO as much as it raises the energy of the HOMO. With electron-deficient di-polarophiles like methyl acrylate, the reaction is dipole HOMO-controlled, and mixtures can be expected. In fact, a 1 1 mixture of regioisomers was obtained in the reaction of (201) with acrylonitrile (equation 9).157... 

In a 500-ml. three-necked round-bottomed flask fitted with a mechanical stirrer and a reflux condenser are placed 50 g. (0.48 mole) of styrene (Note 1) and a previously cooled solution of 100 ml. of concentrated sulfuric acid in 150 ml. of water. The mixture is stirred vigorously (Note 2) and heated under reflux in an oil bath for approximately 4 hours. 

The mechanical stability and ion exchange capacity of these condensation resins were modest. A better approach is to prepare a suitable crosslinked base membrane, which can then be converted to a charged form in a subsequent reaction. Ionics is believed to use this type of membrane in many of their systems. In a typical preparation procedure, a 60 40 mixture of styrene and divinyl benzene is cast onto a fabric web, sandwiched between two plates and heated in an oven to form the membrane matrix. The membrane is then sulfonated with 98 % sulfuric acid or a concentrated sulfur trioxide solution. The degree of swelling in the final membrane is controlled by varying the divinyl benzene concentration in the initial mix to control crosslinking density. The degree of sulfonation can also be varied. The chemistry of the process is ... 

Most dehydrogenations do not occur readily even at high temperatures. The driving force for this reaction is the extension in conjugation that results, since the double bond on the side chain is in conjugation with the ring. Conditions must be controlled to avoid polymerization of the styrene and sulfur may be added to prevent polymerization. The crude product is a mixture of styrene, and ethylbenzene that is separated by vacuum distillation, after which the ethylbenzene is recycled. Usually a styrene plant is combined with an ethylbenzene plant when designed. 

Concentrated sulfuric acid 1s heated to 100°C on a water bath. Styrene-Divinyl Benzene-2x (Dow Chemical Company, Midland, MI) 200-400 mesh is added to the acid so that the final mixture 1s 1 pg copolymer per ml of acid. The mixture was maintained at 100°C and stirred with a glass stirring rod for 15 minutes. The... 

Trost showed that the sulfur ylide 3.68 prepared by the deprotonation of 3.67 with n-butlyllithium (n-BuLi) on reaction with benzaldehyde under the same reaction conditions gave styrene oxide 3.69 as a racemic mixture. 

Prins reaction. 4-Phenyl-/n-dioxane was prepared first by H. J. Prins in 1919 by reaction of styrene and formaldehyde in the presence of sulfuric acid, but the correct structure was inferred only in 1930. A modern procedure calls for stirring a mixture of formalin, coned, sulfuric acid, and styrene under gentle reflux for 7 hrs. The mixture is cooled, and the product collected by extraction with benzene. 

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