Calcium hydride purification

Purification. A three-phase distillation for producing high purity PO has been reported (82). PO can be purified in the laboratory by refluxing with a drying agent, such as calcium hydride, then fractionally distilling (83). Texaco has reported that PO can be purified by extractive distillation (84—89). 

This group of reagents is commercially available in large quantities some of its members - notably lithium aluminium hydride (LiAlH4), calcium hydride (CaH2), sodium borohydride (NaBH4) and potassium boro-hydride (KBH4) - have found widespread use in the purification of chemicals. 

Materials and Purification. Chemicals were purchased from Aldrich chemical company and used as received unless otherwise noted 1,1,1,3,3,3-hexamethyl disilazane, ethylene glycol, triphosgene, poly(ethylene oxide) (MW = 600), poly(tetramethylene oxide) (MW = 1000), poly(caprolactonediol) (MW = 530), toluene diisocyanate (TDI), anhydrous ethanol (Barker Analyzed), L-lysine monohydride (Sigma) and methylene bis-4-phenyl isocyanate (MDI) (Kodak). Ethyl ether (Barker Analyzer), triethylamine and dimethyl acetamide were respectively dried with sodium, calcium hydride and barium oxide overnight, and then distilled. Thionyl chloride and diethylphosphite were distilled before use. 

The required working time is 3 to 4 hours. All equipment is thoroughly dried prior to use and is flushed with an inert gas (argon or nitrogen). Commercial sodium hydroborate is used without purification. The dimethyl ether of diethylene glycol (diglyme) is refluxed over calcium hydride for 8 hours and subsequently distilled over lithium tetrahydroaluminate (lithium aluminum hydride). Commercial tri-n-butylamine is refluxed with acetic anhydride and distilled at atmospheric pressure. 

All the procedures described were performed using dry solvents which were freshly distilled under nitrogen. Tetrahydrofuran and ether were distilled from sodium benzophenone ketal under nitrogen, and dichloromethane from calcium hydride under nitrogen. Petroleum ether (b.p. 40-60 °C) was distilled. Starting materials and solvents were used as obtained from commercial suppliers without further purification unless specified otherwise. 

General. Toluene, chlorobenzene, and o-dichlorobenzene were distilled from calcium hydride prior to use. 4-Dimethylaminopyridine (Aldrich Chemical Co) was recrystalled (EtOAc), and the other 4-dialkylaminopyridines were distilled prior to use. PEG S, PEGM s, PVP s, and crown ethers were obtained from Aldrich Chemical Co., and were used without purification. BuJ r and BU. PBr were recrystallized (toluene). A Varian 3700 VrC interfaced with a Spectraphysics SP-4000 data system was used for VPC analyses. A Dupont Instruments Model 850 HPLC (also interfaced with the SP-4000) was used for LC analyses. All products of nucleophilic aromatic substitution were identified by comparison to authentic material prepared from reaction in DMF or DMAc. Alkali phenolates or thiol ates were pre-formed via reaction of aqueous NaOH or KOH and the requisite phenol or thiophenol in water under nitrogen, followed by azeotropic removal of water with toluene. The salts were transferred to jars under nitrogen, and were dried at 120 under vacuum for 20 hr, and were stored and handled in a nitrogen dry box. 

Laboratory reagent grade methyl methacrylate monomer was dried over powdered calcium hydride and freshly distilled before use. The checkers found that identical yields could be obtained when Matheson Coleman and Bell Chromatoquality methyl methacrylate monomer was used as received with no purification. 

Paliadium(il) acetate (98%, Strem Chemicais Inc.), triphenyiphosphine (99%. Fisher Scientific Co.), and sodium acetate (99%, Ruka Chemika) were used without further purification. N,N-Dimethyiacetamide (DMA) was distilled from calcium hydride through a 25-cm Vigreux column directly before use. 

The submitters purchased benzylamine (99%) from Nacaiai Tesque, Inc. and used it without further purification. The checkers obtained the amine from Aldrich Chemical Company, Inc., and distilled it from calcium hydride. 

The usual techniques of the anionic polymerization have been employed for the solvent purification and the syntheses. The monomer is distilled three times from calcium hydride and then once more just before the polymerization. 

Commercial acetonitrile from Hopkins and Williams (GPR grade, given analysis 0.1% water, 0.02% acid) was used. Further purification of the solvent had no effect on the yield. The checker used MCB reagent-grade acetonitrile, refluxed over and distilled from calcium hydride. 

Fig. 14. Kinetic curves of phenylglycidyl ether polymerization (6.67 mol I-1) under the action of dimethylamine (0.66 moll-1) at 343 K. 1 Pure (chromatography grade) undried phenylglycidyl ether, 2 dried with calcium hydride and dosed in dry argon, 3 precision drying and purification of the reagents in the reaction vessels, reagent dosed in vacuo 1+91...

Aldrich Chemical Company, Inc., and were used without further purification. Dichloromethane used in the preparation of the Mosher ester was obtained from EM Science and was distilled from calcium hydride under a nitrogen atmosphere. (R)-(-)-a-Methoxy-a-(trifluoromethyl)phenyfacetyl chloride was prepared from (S)-(-)-a-methoxy-a-(trifluoromethyl)phenylacetic acid, as described in Note 21. 

Collidine (99% grade) from Aldrich Chemical Company, Inc. was used. Technical grade (from ACROS) can be used after purification by distillation from calcium hydride (CaH2). 

The following chemicals were obtained from Aldrich Chemical Company, Inc. and used without further purification 1,3-dimethoxybenzene (99%) butyl lithium (1.6 M in hexanes) 1-formylpiperdine (99%) boron trifiuoride-diethyl ether (purified, redistilled) 2,3-dichloro-5,6-dicyano-l,4-benzo-quinone (98%), and pyridine hydrochloride (98%). All solvents were reagent grade and were obtained from Fisher Scientific and used without further purification except where noted. Silica gel (230-400 mesh) was obtained from EM Scientific. Chloroform was stored over activated, 4-A molecular sieves for at least 24 h prior to use. Tetrahydrofuran (optima grade) was distilled from sodium benzophenone. Pyrrole (99%) was obtained from Aldrich Chemical Company, Inc. and distilled from calcium hydride. 

Commercial sulfur dioxide (S02) was used without purification. Commercial acrylonitrile (AN) was washed with dilute sulfuric acid and water, dried over calcium hydride, and fractionally distilled. 

All percent yield reported are for compounds that have a purity of approximately 95 % or better as determined by NMR, and compound used for subsequent reaction with out further purification. Diisopropylsilane was prepared from dichlorodiisopropylsilane according to the procedures described in the literature.19 All alcohols were dried over calcium hydride and distilled before use. Rh2(OAc)4, 10 % Pd/C and Mn(CO)5Br were commercially obtained and used without further treatment. 

Purification of the crude (Et4N)2[ReH9] may be effected by the following procedure, which is carried out in a dry-box using acetonitrile dried with calcium hydride and ether distilled from lithium tetrahydroaluminate. The product is dissolved in acetonitrile (40 ml.), and ether (50 ml.) is immediately added to precipitate a white or light tan solid which is collected by... 

Butyne-1,4-diol, sodium hydride (60% in oil) and dimethyl malonate were purchased from Aldrich Chemical Company, Inc. and used without further purification. Triethylamine and dichloromethane were distilled from calcium hydride prior to use. 

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