Solution formation recrystallization

The ability of the boron atom of 59 to engage in a donor-acceptor interaction was illustrated with DMAP and DABCO (DABCO = diazabi-cyclo-[2.2.2]-octane) that readily formed the corresponding Lewis adducts. Interestingly, a similar behavior was retained after coordination of the phosphorus atom to palladium. The formation of the Lewis base adducts 66a and 66b of complex 65 (Scheme 38) was supported by solid-state 31P and nB CP/MAS-NMR spectroscopy (<5 1 B = 5-6 ppm), although the occurrence of decomposition and/or dissociation processes impeded spectroscopic characterization in solution and recrystallization to obtain X-ray quality crystals. Compounds 66a and 66b substantiate the ability of ambiphilic compounds to engage concomitantly into the coordination of donor and acceptor moieties. Such a dual behavior opens interesting perspectives for the preparation of metallo-polymers and multimetallic complexes. 

The short-term potential for solid solution formation is low for minerals with small solubility products, such as aluminum oxides and aluminosilicates, because spontaneous dissolution and recrystallization is very slow in these minerals. Without recrystallization, trace metals cannot be incorporated into the mineral structures. Movement of metal ions into these mineral crystals by solid diffusion is not possible on the time scale of adsorption experiments ionic diffusion into most crystalline solids is negligibly slow at all but extremely high temperatures. Nevertheless, metals could diffuse into imperfect solids along interstices, pores, or other structural defects. 

For synthesis of a Fe-Cu alloy [434] the dodecyl sulfates Cu(DS)2 and Fe(DS)2 were first synthesized via reaction of sodium dodecyl sulfate (SDS) with ferrous or copper chloride. The precipitate obtained as the reaction product on standing at 2°C was repeatedly washed with iron or copper chloride solution and recrystallized in distilled water. A mixed surfactant micellar composition close to the CMC with 30% Fe(DS)2 and 70% Cu(DS)2 was prepared, and NaBH4 was added to it. Synthesis was carried out in a glove box under nitrogen atmosphere to prevent oxidation of the products. The solution showed an immediate change to a dark color along with the formation of nanoparticles (< 10 nm). X-ray diffraction of the particles showed the fee structure and electron microscopy showed interconnected networks. The estimated average composition of the product was found to be 14%... 

Cyanides. Salts of the complex ion, [Au(CN)2] , can be formed directiy from gold, ie, gold dissolves ia dilute solutions of potassium cyanide ia the presence of air. Additionally, a gold anode dissolves ia a solution of potassium cyanide. The potassium salt can be isolated by evaporation of the solution and purified by recrystallization from water (177). Boiling of the complex cyanide ia hydrochloric acid results ia formation of AuCN [506-65-01]. Halogens add oxidatively to [Au(CN)2] to yield salts of [Au(CN)2X2] which are converted to the tetracyanoaurates usiag excess cyanide (178). These last can also be prepared directiy from the tetrahaloaurates. 

Gas AntisolventRecrystallizations. A limitation to the RESS process can be the low solubihty in the supercritical fluid. This is especially evident in polymer—supercritical fluid systems. In a novel process, sometimes termed gas antisolvent (GAS), a compressed fluid such as CO2 can be rapidly added to a solution of a crystalline soHd dissolved in an organic solvent (114). Carbon dioxide and most organic solvents exhibit full miscibility, whereas in this case the soHd solutes had limited solubihty in CO2. Thus, CO2 acts as an antisolvent to precipitate soHd crystals. Using C02 s adjustable solvent strength, the particle size and size distribution of final crystals may be finely controlled. Examples of GAS studies include the formation of monodisperse particles (<1 fiva) of a difficult-to-comminute explosive (114) recrystallization of -carotene and acetaminophen (86) salt nucleation and growth in supercritical water (115) and a study of the molecular thermodynamics of the GAS crystallization process (21). 

A total of 3 g (0.13 moles) of sodium hydride is added to a solution consisting of 10 g of 17 -hydroxy-5a-androstan-3-one (36 mmoles) in 200 ml of benzene and 10 ml of ethyl formate. The reaction mixture is allowed to stand under nitrogen for 3 days followed by dropwise addition of 10 ml of methanol to decompose the excess of sodium hydride. The solution is then diluted with 300 ml water and the layers are separated. The basic aqueous solution is extracted with ether to remove neutral material. The aqueous layer is acidified with 80 ml of 3 A hydrochloric acid and the hydroxymethylene steroid is extracted with benzene and ether. The combined organic extracts are washed with water and saturated sodium chloride solution and then dried over magnesium sulfate and concentrated. The residue, a reddish-yellow oil, crystallized from 10 ml of ether to yield 9.12 g (83%) of 17 -hydroxy-2-hydroxymethylene-5a-androstan-3-one mp 162-162.5°. Recrystallization from chloroform-ether gives an analytical sample mp 165-165.5° [a]o 53° (ethanol) 2 ° 252 mjj. (g 11,500), 307 m u (e 5,800). 

Alkylquinazolines are catalytically reduced to the corresponding 3,4-dihydro derivatives/ The only example of a 4-substituted quin-azoline which was reduced to its 3,4-dihydro derivative is 2-chloro-4-phenylquinazoline which gave 4-phenyl-3,4-dihydroquinazoline/ 4-Methylquinazolines are susceptible to oxidation, as is shown by the attempted nitration of 2,4-diraethylquinazoline which causes the removal of the methyl group with formation of 4-hydroxy-2-methyl-6-nitroquinazoline/ When the 4-substituent is —C(Et) (C02Et)2 recrystallization of the picrate from ethanol is sufficient to convert it to 4-hydroxyquinazoline/ Similar hydrolyses occur in acid solution and the mechanism undoubtedly involves a hydrated intermediate/... 

A solution of 200 g of 1 -p-chlorophenvl-2-phenyl-4-(N-pvrrolidino)-butanol-2 in 750 ml of concentrated hydrochloric acid is refluxed for 9 hours thereby causing a dehydration of the butanol compound, and the formation of the hydrochloric acid addition salt of a 1 -p-chloro-phenyl-2-phenyl-4-(N-pyrrolidino)-butene. The hydrochloride salt formed crystallizes in the oily lower layer of the two phase reaction mixture and is removed therefrom by filtration. The filtrate is again refluxed for 9 hours, cooled to0°C,and a second crop of the hydrochloric acid addition salt of the dehydration product is obtained and filtered off. The filtrate containing residual amounts of 1 -p-chlorophenyl-2-phenyl-4-(N-pyrrolidino)-butanol-2 is again refluxed for 9 hours to yield an additional crop of the salt of the dehydration product. The several fractions of the butene compound are combined and triturated with several small portions of hot acetone and recrystallized from alcohol-ether mixture. The hydrochl or ic acid addition salt of the dehydration product, 1 -p-chlorophenyl-2-phenyl-4-(N-pyrrolidino)-butene hydrochloride, melts at about 227°C to 228°C. 

Another procedure145 consists of bubbling of sulfur dioxide through a chilled solution of diazomethane in ether146. Evaporation of the solvent leaves the crude thiirane dioxide, which can be further purified by either distillation under reduced pressure or recrystallization. The formation of the thiirane dioxides is usually accompanied by formation of the corresponding olefins, along with small amount of ketazines. 

The paper electrophoresis experiments carried out to study the mobility of polynuclear technetium clusters in aqueous solutions of HX of varying acidity, as a mobile phase, showed that these clusters were also characterized by reversible reactions such as (5) without leading to destruction of M-M bonds. On the other hand, an autoclave recrystallization of the polynuclear clusters at 200-220°C in an atmosphere of argon from concentrated solutions of HX led to a partial destruction of M-M bonds and the formation of binuclear complexes [Tc2X8]3 and [Tc,X6]2. This indirectly shows that reactions (6) and (7), leading to the destruction of M-M bonds, are likely in solutions of polynuclear clusters [15]. 

The acidic isomer can be recrystallized from ethanol without the formation of any of the basic isomer. The checkers used for each gram of product 5 ml. of ethanol and 2.5 ml. of water. After solution of the product, treatment with Darco and filtration, 2.5 ml. of water was added to the hot solution. 

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