Vacuum distillation styrene purification

Styrene monomer was purified by vacuum distillation over CaHi. Inhibitor in styrene was removed using activated alumina. N-heptane was purified by distillation over sodium to remove tire trace of residual moisture. The purified slyreaie and n-heptane were stored over activated alumina under nitrogen blanket. Et[Ind]2ZrCl2 Strem Chem.), MAO (modified methylaluminoxane, type 3A, Akzo Novel) wee used without fiirtha" purification. 

Styrene (Fisher), p-methylstyrene (Mobil), and t-butylstyrene (DOW) were purified by passing through a column of activated alumina and then carefully degassed to remove all traces of 0. Further purification by vacuum distillation from dibutyl magnesium resulted in anionically pure monomers. 

Butadiene (B) sionomer vas flashed at 46 C from Its dimer and Inhibitor, then condensed by passing through activated alumina Into the container at -15 C under N2 pressure. Styrene (S), was either dried through activated alumina, or refluxed over CaH2 then vacuum distilled. e-Caprolactone (CL) was distilled from CaR2 at reduced pressure. Ethylene oxide (EO) was purchased from Eastman Chemical Co., diluted in dried cyclohexane before use and used without further purification. n-Butyllithlum (n-BuLi) In heptane was obtained from Alfa Products and dlethylalumlnum chloride (DEAC) was from Texas Alkyls. They were diluted In purified cyclohexane before... 

Anionic techniques were used to synthesize the block polymers which function as precursors to ion containing block polymers. Monomers were carefully dried by repeated vacuum distillation from CaH2. Distillation from dibutyl magnesium was also utilized for the final purification of the hydrocarbon monomers, styrene and diphenyl ethylene. The methacrylate monomers may also be finally purified... 

Materials. VEC was prepared by the catalyzed addition of CO2 to 3,4-epoxy-l-butene using conditions typical of that used industrially [77], then purified by vacuum distillation. Other raw materials were used as received without any additional purification. Mixed xylenes, vinyl acetate (VA), butyl acrylate (BA), butyl methacrylate (BMA), methyl methacrylate (MMA), styrene (St), and t-butyl hydroperoxide were obtained from Aldrich Chemical Company. Lupersol 575 (t-amyl peroxy (2-ethylhexanoate)) was supplied by Elf Atochem. Vazo 67 (2,2 -azobis(2-methylbutyronitrile)) was obtained from DuPont Chemical Company. Vinyl pivalate (NE05), vinyl 2-ethylhexanoate (V2EH), Tergitol NP-40 (non-ionic surfactant) and QP-300 (hydroxy ethyl cellulose) were obtained from Union Carbide Coq)oration. Aerosol OT-75 (surfactant) was obtained from Cytec. Sodium formaldehyde sulfoxylate was obtained from Henkel Corporation. Ethyl 3-ethoxy propionate (EEP), propylene glycol monomethyl ether (PM) and PM acetate (PM Ac) are Eastman Chemical Company products. 

In contrast to alkylation of benzole, dehydration of ethyl benzole is endothermic. This process is carried out at high temperatures of 550-600 °C by means of heterocatalysis. The resulting styrene, to which a polymerization inhibitor has been added, is then vacuum-distilled before further processing. This complex purification procedure is made necessary by the close proximity of the boiling points of ethyl benzole and styrene. 

Purification of the crude styrene must be carried out at the lowest possible temperature by vacuum distillation, to avoid polymerization as a further measure to suppress the tendency to polymerize, polymerization inhibitors, such as 4-tert-butylcatechol, are added. 

The dehydrogenation reaction produces crude styrene which consists of approximately 37.0% styrene, 61% ethylbenzene and about 2% of aromatic hydrocarbon such as benzene and toluene with some tarry matter. The purification of the styrene is made rather difficult by the fact that the boiling point of styrene (145.2°C) is only 9°C higher than that of ethylbenzene and because of the strong tendency of styrene to polymerise at elevated temperatures. To achieve a successful distillation it is therefore necessary to provide suitable inhibitors for the styrene, to distil under a partial vacuum and to make use of specially designed distillation columns. 

Isoprene (99 + %, Aldrich) and styrene (99%, Aldrich) were purified by initial stirring and degassing over freshly crushed Cal on a high vacuum line followed by distillation onto dibutyl-magnesium (Alpha Inorganics). Final purification involved distillation from this solution directly into calibrated ampoules and sealing with a flame. Benzene (Fisher, Certified ACS) was stored over cone. 

The photolysis was carried out on a degassed solution in a closed Vycor tube equipped with sidearms and internal cooling. The light source was a 450-W Hanovia lamp. 5-Diazo-10,l 1-dihydrodibenzo-[fl,rf]cycloheptene (1.0 g, 4.5 mmol) was dissolved in freshly distilled 4-methoxystyrene (20 mL) and irradiated for ca. 1.5 h at 25 °C the diazo compound was completely consumed. Excess styrene was removed under vacuum, and purification by column chromatography on silica gel (0.02-0.5 mm) eluting with ben-zene/CH2Cl2 (1 1) gave 1.2 g (81%) of product mp 100 °C. 

Sodium-p-styrene sulfonate (SST) was supplied by Exxon Research and Engineering Co. and used without further purification. n-Butyl acrylate was a product of Polysciences, Inc. and was passed through a column of neutral alumina, twice, before use to remove the inhibitor. Potassium persulfate and sodium bisulfate were recrystallized from distilled water and dried under vacuum. 

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