Gels, crystallization from

PE/i-PP blend films were prepared by gel crystallization from semidilute decalin solution as reported by Balta Calleja et al. (1990b), using ultra-high-molecular-weight PE (M2 = 6 X 10 ) and i-PP (M , = 4.4 x 10 ). In addition to the individual PE and i-PP homopolymer dry gels, Baltd Calleja et al. investigated PE/i-PP compositions of 75/25, 50/50 and 25/75. For all compositions a concentration of about... 

Significant amounts of comonomer also reduce the abiUty of the polymer to form lamellar crystals from solution. In some cases, the polymer merely gels the solution as it precipitates rather than forming distinct crystals. At somewhat higher VDC content, it may precipitate in the form of aggregated, ill-defined particles and clusters. 

A mixture of 3.18 g (10 mmoles) of 17 -hydroxy-2-hydroxymethylene-5a-androstan-3-one, 20 ml dry dimethyl formamide and 0.3 g (13 mmoles) of sodium hydride is stirred for 0.5 hr at room temperature under nitrogen. A total of 1.51 g (12.5 mmoles) of redistilled allyl bromide is added and the mixture is stirred for 1 hr on the steam bath. Aqueous potassium hydroxide (2 g in 5 ml of water) is added and stirring is continued for 1 hr on the steam bath. The reaction mixture is diluted with 50 ml of methylene dichloride followed by careful addition of 300 ml of water. The organic phase is separated and the aqueous phase is again extracted with 50 ml of methylene dichloride. The combined extracts are washed with water, dried over sodium sulfate, filtered and chromatographed on 200 g of silica gel. Elution with pentane-ether (4 1) provides 2a-allyl-17j -hydroxy-5a-androstan-3-one 0.85 g (26%) mp 118-119° [aj 14° (CHCI3), after crystallization from ether-hexane. 

Irradiations of Testosterone Acetate (114), —In t-Butanol. 1.25 g of (114) in 250 ml t-butanol is irradiated for 32 hr at 30° under nitrogen with a Hanau Q81 high-pressure mercury lamp placed in a central water-cooled Pyrex immersion well with acetone filter. The solvent is evaporated in vacuo and the residue chromatographed on 125 g silica gel with benzene-ethyl acetate (4 1) to yield 0.29 g 17 -hydroxy-la,5 -cyclo-10a-androstan-2-one acetate [(118) 23%] mp 164-165°, after crystallization from acetone-hexane [a]i3 37 (CHCI3) 0.14 g cyclopentanone (120) (11%) mp 106-107° [aJo 38° (CHCI3) and 0.58 g starting material [(114) 46%]. Ratio (118) (120) - 2 1. 

With 2537 k-Light. 1 g (140) in 140 ml anhydrous dioxane is irradiated for 20 hr at room temperature with a Hanau NK 6/20 low-pressure mercury lamp placed in a central water-cooled quartz finger. 0.19 g of (141) crystallize from the crude reaction mixture as described above. Chromatography of the residual material on silica gel with benzene-ethyl acetate (4 1) gives 0.29 g of B-nortestosterone acetate [(142) 28.5 %] and starting material (140). 

A mixture of 2.3 parts of 2-(4-methoxyphenyl)ethyl methanesulfonate, 4.9 parts of 1-[(4-fluorophenyOmethyl] -N-(4-piperidinyl)-1H-benzimidazol-2-amine dihydrobromide, 3.2 parts of sodium carbonate, 0.1 part of potassium iodide and 90 parts of N,N-dimethylformamide is stirred overnight at 70°C. The reaction mixture is poured onto water. The product is extracted with methylbenzene. The extract is washed with water,dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using a mixture of trichloro-methane and methanol (98 2 by volume) as eluent. The pure fractions are collected and the eluent is evaporated. The residue is crystallized from 2,2 -oxybispropane, yielding 2.2 parts (48%) of 1 -(4-fluorophenvlmethyl)-N-[1 - [2-(4-methoxvphenyl)ethvl] -4-piperidinyl] -1H-benzlmidazol-2-amine MP 149.1°C. 

After having been dried over sodium suifate and evaporated under vacuum, this extract gives as a solid residue 14.7 g of crude 7-cyanoacetylamino-cephalosporanic acid which is purified by chromatography on 30 times its own weight of silica gel. The fractions eluted with chloroform plus acetone (7 3) furnish a product which crystallizes from acetone plus ether in the form of needles melting at 168° to 170°C with decomposition. 

After the end of the fermentation (28 hours) the culture broth is filtered off by suction over a large suction filter. The mycel residue is washed with water several times. The filtrate is extracted three times, each time with 10 liters of methyl isobutyl ketone. The extract is concentrated under vacuum in a circulating evaporator and in a round flask carefully dried under vacuum. The residue is crystallized from acetone/isopropyl ether. The melting point is 157°-158°C (fermentation yield = 60%). The pure product yield obtained after a second crystallization and chromatography of the mother liquor on silica gel amounts to 53% of the theoretical. 

Preparation of a-Acety/amino-0-(5-Benzy/oxy-/ndo/yl-3)-Propionic Acid 15 grams a-acetyl-amino-0 -carboxy-/3-(5-benzyloxy-indolyl-3)-propionic acid was suspended in 225 ml water and the suspension refluxed and stirred in a stream of nitrogen until evolution of carbon dioxide ceased (about 2 hours). After cooling somewhat, 120 ml ethyl alcohol was added and the suspension refluxed until the product dissolved. Charcoal was added to the solution the mixture filtered hot, and the filter-cake washed with 50 ml hot 50% aqueous ethanol. 0 -Acetylamlno-/3-(5-benzyloxy-indolyl-3)-propionic acid, MP 164° to 166°C, which crystallized from the filtrate on cooling, was collected, washed with an ice-cold mixture of 15 ml ethanol and 45 ml water, and dried in vacuo over silica gel (yield 11.1 grams, 83%). 

A mixture of 4.98 g of acetoacetic acid N-benzyl-N-methylaminoethyl ester, 2.3 g of aminocrotonic acid methyl ester, and 3 g of m-nitrobenzaldehyde was stirred for 6 hours at 100°C in an oil bath. The reaction mixture was subjected to a silica gel column chromatography (diameter 4 cm and height 25 cm) and then eluted with a 20 1 mixture of chloroform and acetone. The effluent containing the subject product was concentrated and checked by thin layer chromatography. The powdery product thus obtained was dissolved in acetone and after adjusting the solution with an ethanol solution saturated with hydrogen chloride to pH 1 -2, the solution was concentrated to provide 2 g of 2,6-dimethyl-4-(3 -nitrophenyl)-1,4-dihydropyridlne-3,5-dicarboxylic acid 3-methylester-5- -(N-benzyl-N-methylamino)ethyl ester hydrochloride. The product thus obtained was then crystallized from an acetone mixture, melting point 136°Cto 140°C (decomposed). 

Reprecipitation from acetone/pentane is repeatedly effected until the condensation product suits in flaky form. Further purification is effected in that the crude product is chromatographed on silica gel. The fractions which are uniform in accordance with thin layer chromatography are combined and yield crystals from absolute alcohol. Pure 4 -demethylepipo-dophyllotoxin-/3-D-thenylidene glucoside has a melting point of 242°C to 246°C (last residue up to 255°C). 

A solution of 438 mg of diac in methanol (20 ml) and ammonia solution (SG 0.88 20 ml) was iodinated at 0°C with 1.8 ml 1 N iodine solution. The product was isolated in almost theoretical yield in a manner similar to that described for tetrac. After crystallization from 50% (v/v) methanol, triac was obtained as colorless needles which melted over the range 65°C to 90°C according to the rate of heating. The molten form resolidified at about 110°C and finally melted at 180 C to 181°C without decomposition. The compound, dried at 25°C/3 mm over silica gel, contains methanol of crystallization. 

Cu(OAc), H20 (0.75 g, 3.7 mmol) was added to a refluxing solution of metal-free 1,4,8,11.15,18,22,25-octa(propyloxy)phthalocyanine (0.1 g, 0.1 mmol) in BuOH (5 mL). The solution was maintained at reflux for 0.5 h, cooled, and chromatographed (silica gel, CH2C12 and Et20). The green-blue fraction eluted first was crystallized from a slowly evaporating solution in CH2Cl2/py yield 0.086 g (81 %). 

To a solution of 1 equiv of( + )-(R)-methyl 4-tolyl sulfoxide (1) inTHF is added a solution of 1 equiv of LDA at 0°C and, after cooling to —78 C, a solution of 1 equiv of an appropriate imine 2. Addition is usually complete within 10 min. The reaction is quenched with dilute HCI, extracted with CH,C12 and the extracts are dried and evaporated. The products are purifed by Hash chromatography (silica gel). The main diastcreomer can be isolated by crystallization from cyclohexane. No further preparative details are available. 

To a stirred solution of 4 mmol of the diamide in 40 mL of dioxane (distilled from LiAlH4) and 13 mL of water is added 1 mg of osmium tetroxide. When the solution turns brownish (after about 10 min) 2.06 g (9.2 mmol) of sodium metaperiodale are added at 25 26 "C. The progress of the reaction is monitored by TLC on silica gel coated plastic sheets with CHCI,/diethyl ether/methanol (3.3 0.1) as eluent. When the reaction is complete, the precipitated solid is filtered and the filtrate concentrated in vacuo at 1 Torr. The residue is dissolved in 50 mL of CHC13, dried over MgSO,. and evaporated in vacuo to leave a residue, which is crystallized from a suitable solvent. 

When dried in an oven, hydrated silica loses its water and becomes a desiccant (a substance that attracts water from the air). You find little packets of silica gel crystals in containers whose contents would be damaged by condensing moisture, such as vitamin bottles, consumer electronics, pepperoni, or leather products. 

A solution of 1 mmol 1017 in 4 mL dry DMF is treated with MesSiCl 14 (0.63 mL, 5 mmol) then with triethylamine (0.7 mL, 5 mmol) at room temperature. After stirring until completion of the reaction the mixture is poured into dilute HCl, extracted with ethyl acetate, and the product isolated by column chromatography on sihca gel with hexane-ethyl acetate (3 1) as mobile phase to give, on crystallization from ethyl acetate, 91% N-hydroxyindole 1019, m.p. 218-220 °C (dec.) [93, 94] (Scheme 7.63). 

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