Benzene, high-pressure crystallization from

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. 

The crystal of 2 OPr recrystallized from EtOH/H20 solution, and the mixed crystal of the same ethyl and propyl cinnamate derivatives (2 OEt and 2 OPr), on photoirradiation for 2h at room temperature with a 500 W super-high-pressure Hg lamp, afforded the highly strained tricyclic [2.2] paracyclophane (2 OEt-2 OPr-cyclo) crystal quantitatively (Maekawa et ai, 1991b). A crystal structure analysis was carried out of a single crystal of the complex of 2 OEt-2 OPr-cyclo with HFIP (recrystallization solvent) in a 1 2 molar ratio. Fig. 13 shows the molecular structure of 2 OEt-2 OPr-cyclo viewed along the phenylene planes. The short non-bonded distances and deformation of the benzene rings, as seen in Fig. 13, are common to those of [2.2] paracyclophanes, as previously reported (Hope et ai, 1972a,b). 

Irradiation of (+ )-crystals of 96 with a 400 W high-pressure Hg-lamp, with occasional grinding with an agate mortar and pestle for 40 h at room temperature gave ( + )-97 of 93 % ee in 74 % yield. Irradiation of (—)-crystals of 96 under the same conditions gave (—)-97 of 93 % ec in 75% yield48. Purification to 100% ee can easily be achieved by recrystallization from benzene. Although the photochemical conversion of 96 into 97 on irradiation in the solid state has been reported, enantioselectivity of the reaction has not been discussed 441. 

Irradiation of the powdered crystals of 6a-d with a high-pressure mercury lamp under argon at 0 °C showed a different photochemical behavior from that in benzene solution. Contrary to the photochemical results in solution media in which azetidin-2-ones 8 (y-hydrogen abstraction products) were formed as major products, thioketones 7 (P-hydrogen abstraction products) were obtained as major components in the solid-state photoreactions (Scheme 7). The... 

The experimental conditions and results of the analysis of the purity of separated benzene crystals are shown in Table 1. In tests of No. 1-1 to 1-4, and 3-1 and 3-2, the melt was compressed to the pressure shown in Table 1 and kept on the same value, without seed crystals. Nucleation occured on the wall and crystals grew there. In tests of No.2-1, 2-2 and 3-3, seed crystals were made as described above they grew both inside the optical cell and on the wall. In these tests, since the melt around benzene crystals was replaced by the water, the crystals were taken out without serious destruction. The shapes of benzene crystals were dendritic, and purity of it was over 99.9 mole percent, independent from the operational conditions and the feed compositions as shown in Table 1. Therefore, crystals obtained by high pressxire crystallization is considered to be very pure due to the complete removement of mother liquid from crystal surface. 

The compound is very soluble in liquid ammonia, solutioirs changing from faint yellow to orange as the concentration increases. Concentrated solutions are extremely viscous, and crystals from liquid ammonia solutions contain 3 mols. of ammonia of crystallisation, which are readily eliminated at low pressures. Sodium triphenyl germanide is also very soluble in benzene saturated with ammonia, and fairly soluble in ether and pure benzeixe. Solutions in liquid ammonia are as highly ionised as ordinary salts, and benzene solutions in the presence of ammonia readily conduct the current. Sodium triphenyl germanide... 

UV irradiation of a dry benzene soln (120 mL) containing 1,1-diarylethene (0.40-0.05 mol) and diphenyldiazomethane (0.15-0.076 mol) was carried out in an immersion-type irradiation vessel equipped with a mercury high-pressure lamp (Philips, HP 125 W) surrounded by a quartz water jacket. The solution was purged with Oj-free Nj for 15 min prior to the photochemical reaction, which was run under dry Nj. Irradiation, performed at 13 °C, lasted for about 15-30 h. The workup procedure consisted of removal of benzene followed in some cases by column chromatography (50 cm) of the oily product on acidic alumina with various solvents and recrystallization of the colorless crystals from EtOH. 

A mixture of 2-diazo-3,4-bis(diphenylmethylene)cyclobutanone (1, 424 mg, 1 mmol) in MeOH (20 mL) and benzene (150 mL) was irradiated (100-W high-pressure Hg lamp) for 2 h. Evaporation of the solvent on a rotary evaporator under vacuum gave an oily residue which was chromatographed (silica gel, benzene), to afford crude crystals. Recrystallization from EtOH afforded the product as colorless prisms yield 372 mg (87%) mp 157-159 X. 

Sodium, lithium,and indium have been reported to be SERS active. In a series of papers, Krasser et 98,99,269-271 reported Raman scattering from CO and benzene adsorbed on high-surface-area Ni catalysts. Stencel and Bradley obtained, under relatively high pressures of CO, Raman spectra from nickel single crystals. The spectra were very poor, of about 10 cps. The apparent enhancement factor is unreported. Borov et al also see... 

PAH clusters can also be seen as intermediate species between isolated PAHs and PAH crystals, for which border eflects have completely disappeared. In this context, one can mention the investigation of the rearrangement of benzene crystals submitted to high pressure to extract a phase diagram from the molecular crystal to saturated polymer [170] and the calculation of absorption electronic spectra of substituted pyrene crystals [171]. 

The gas is soluble with difficulty in water, but very easily soluble in alcohol and ether. It combines directly with ammoiua, yielding hmon trimethylammine, BMcg.NH, M.pt. 56° C., B.pt. 110° C., which crystallises from ether in many-sided, highly refractive, volatile crystals. The compound has the vapour pressures 1-0 mm. at 0° C., 1 8 mm. at 5 6° C., 2 mm. at 10° C., 3 2 mm. at 15-2° C., 11-0 mm. at 31-2° C, and 16-5 mm. at 36 9° C. The vapour density, measured between 25-0° C. and 70-0° C., shows that about 10 per cent, of undissoeiated ammine can exist in the gaseous state at 25° to 30° C., but molecular weight determinations in benzene solution by the cryoscopic method show that the ammine is practically undissociated. The benzene solution is stable in air, smells faintly of boron trimethyl, but not of ammonia. 

---