Linde Type

Acetonitrile, 99%, supplied by Aldrich Chemical Co., was dried over Linde type 4A molecular sieves for 12 hr and decanted. 

Liquid Water Linde Type 4 A Linde Type 5 A Activated Alumina Silicic Acid Gel... 

Butanediol (tetramethylene glycol) [110-63-4] M 90.1, f 20.4 , b 107-108 /4mm, 127 /20mm, d 1.02, n 1.4467. Distd and stored over Linde type 4A molecular sieves, or crystd twice from anhydrous diethyl ether/acetone, and redistd. Also purified by recrystn from the melt and doubly distd in vacuo in the presence of Na2S04. 

Shaken with aq KMn04 to remove material absorbing around 230-240nm, then dried with Linde type 13X molecular sieves and fractionally distd. 

Cyclooctanone [502-49-8] M 126.2, m 42". Purified by sublimation after drying with Linde type 13X molecular sieves. 

Dimethyl carbonate [616-38-5] M 90.1, m 4.65", b 90-91", d 1.070, n 1.369. Contains small amounts of water and alcohol which form azeotropes. Stood for several days in contact with Linde type 4A molecular sieves, then fractionally distd. The middle fraction was frozen slowly at 2°, several times, retaining 80% of the solvent at each cycle. 

The acetal (b 82.5°) is removed during fractional distn. Traces of benzene, if present, can be removed as the benzene/MeOH azeotrope by distn in the presence of MeOH. Distn from LiAlHa removes aldehydes, peroxides and water. Dioxane can be dried using Linde type 4X molecular sieves. Other purification procedures include distn from excess C2H5MgBr, refluxing with Pb02 to remove peroxides, fractional crystn by partial freezing and the addition of KI to dioxane acidified with aq HCl. Dioxane should be stored out of contact with air, preferably under N2. 

MgS04 or NaOH and distd under vacuum. Further dried by reaction with sodium under nitrogen, refluxed for several hours and distd. The distillate was then passed through a column of Linde type 4A molecular sieves and finally distd under nitrogen, from more molecular sieves. Fractionally distd. 

Isobutyronitrile (2-methylpropionitrile, isopropyl cyanide) [78-82-0] M 69.1, b 103.6 , d 0.7650, n 1.378. Shaken with cone HCl (to remove isonitriles), then with water and aq NaHC03. After a preliminary drying with silica gel or Linde type 4A molecular sieves, it is shaken or stirred with CaH2 until hydrogen evolution ceases, then decanted and distd from P2O5 (not more than 5g/L, to minimize gel formation). Finally it is refluxed with, and slowly distd from CaH2 (5g/L), taking precautions to exclude moisture. 

Dried with Linde type 5A molecular sieves or Na2S04 and fractionally distd at reduced pressure. Alternatively, it was refluxed with, and distd from, BaO. Also purified by fractional crystn from the melt and distd from zinc dust. Converted to its phosphate (m 135°) or picrate (m 223°), which were purified by crystn and the free base recovered and distd. [Packer, Vaughn and Wong J Am Chem Soc 80 905 1958.] The procedure for purifying via the picrate comprises the addition of quinoline to picric acid dissolved in the minimum volume of 95% EtOH to yield yellow crystals which are washed with EtOH and air dried before recrystn from acetonitrile. The crystals are dissolved in dimethyl sulfoxide (previously dried over 4A molecular sieves) and passed through a basic alumina column, on which picric acid is adsorbed. The free base in the effluent is extracted with n-pentane and distd under vacuum. Traces of solvent are removed by vapour phase chromatography. [Mooman and Anton J Phys Chem 80 2243 1976.]... 

Dried with Linde type 5A molecular sieves, BaO or sodium, and fractionally distd. The distillate (200g) was heated with benzene (500mL) and cone HCl (150mL) in a Dean and Stark apparatus on a water bath until water no longer separated, and the temperature just below the liquid reached 80°. When cold, the supernatant benzene was decanted and the 2,4-lutidine hydrochloride, after washing with a little benzene, was dissolved in water (350mL). After removing any benzene by steam distn, an aqueous soln of NaOH (80g) was added, and the free... 

Styrene is difficult to purify and keep pure. Usually contains added inhibitors (such as a trace of hydroquinone). Washed with aqueous NaOH to remove inhibitors (e.g. rert-butanol), then with water, dried for several hours with MgS04 and distd at 25° under reduced pressure in the presence of an inhibitor (such as 0.005% p-tert-butylcatechol). It can be stored at -78°. It can also be stored and kept anhydrous with Linde type 5A molecular sieves, CaH2, CaS04, BaO or sodium, being fractionally distd, and distd in a vacuum line just before use. Alternatively styrene (and its deuterated derivative) were passed through a neutral alumina column before use [Woon et al. J Am Chem Soc 108 7990 1986 Collman J Am Chem Soc 108 2588 1986]. 

V,7V,7V, 7V -Tetramethylethylenediamine (TMEDA, TEMED) [110-18-9] M 116.2, b 122°, d 1.175, n 1.4153, pK 5.90, pKj 9.14. Partially dried with molecular sieves (Linde type 4A), and distd in vacuum from butyl lithium. This treatment removes all traces of primary and secondary amines and water. [Hay, McCabe and Robb J Chem Soc, Faraday Trans 1 68 1 1972.] Or, dried with KOH pellets. Refluxed for 2h with one-sixth its weight of n-butyric anhydride (to remove primary and secondary amines) and fractionally distd. Refluxed with fresh KOH, and distd under nitrogen. [Cram and Wilson 7 Am C/iem Soc 85 1245 796i.] Also distd from sodium. 

The general purification methods listed for xylene are applicable. p-Xylene can readily be separated from its isomers by crystn from such solvents as MeOH, EtOH, isopropanol, acetone, butanone, toluene, pentane or pentene. It can be further purified by fractional crystn by partial freezing, and stored over sodium wire or molecular sieves Linde type 4A. [Stokes and French J Chem Soc, Faraday Trans 1 76 537 1980.]... 

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. 

The checkers used reagent-grade toluene dried over Linde type 5A molecular sieves. 

The submitters used reagent-grade acetonitrile (Mallinckrodt Chemical Works) dried prior to use by storage over Matheson Linde type 4A molecular sieves. The checkers used reagent-grade acetonitrile obtained from Ishizu Pharmaceutical Company, Japan, dried prior to use by storage over 4A molecular sieves obtained from Nakarai Chemicals, Ltd., Japan. 

The submitters used tri-Ji-propylaniine obtained from Aldrich Chemical Company, Inc., and the checkers used tri-n-propylamine obtained from Wako Pure Chemical Industries, Ltd., Japan. Both groups stored the reagent over Linde type 4A molecular sieves prior to use,... 

A7,AT-Dimethylformamide was dried overnight over Linde type 4A molecular sieves. 

The submitters dried dimethyl sulfoxide using Linde type 3A molecular sieves. The checkers distilled this reagent from calcium hydride at 10 mm. prior to use. 

N,N-Dimethylformamide was purified by distillation from calcium hydride under a nitrogen atmosphere and stored over Linde type 4A molecular sieves. 

Anhydrous ethyl ether purchased from Fisher Scientific Company or Mallinckrodt Chemical Works was dried over Linde type 3A molecular sieves. The checkers degassed the solvent immediately before use by evacuating and filling the container with nitrogen three times. 

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