Acetonitrile process

Quaternary ammonium salts of triphenylmethane acetonitriles Process of preparing cyanides of triarylrnethane dyes... 

FIGURE 21.5 Top Plot of concentration of the acid form of 3 versus time for self-decomposition of 3 in acetonitrile process solution at 49.5°C. Bottom Plots of Ln 3 versus time. 

FIGURE 21.6 Plots of concentration of the free acid and anion forms of 3, and 5 in acetonitrile process solution versus time. Reaction conditions 0.3 equiv of TFA and 1.0 eqniv of triazole HCl salt 4 at 49.5°C. [HA] plus [A ] dashed line is based on online IR data. Circles are obtained by HPLC analyses. For reaction sequence, see Scheme 21.5. (Reprinted with permission from J. Am. Chem. Soc., 126, 40, 13003-13009. Copyright 2004. American Chemical Society.)... 

The product (183) is formed on irradiation of acridine (184) phenothiazine (185) crystals in which the ratio of the reactants is 3 4," This reactivity is different from the solution phase (in acetonitrile) process which affords both (183) and the dihydro dimer (186). The photoinduced electron transfer reactions of some a-silyl ethers has been investigated." The sensitizing system uses DCA/ biphenyl and irradiation at A, > 345 nm in acetonitrile/methanol. The irradiation brings about the formation of the radical cation (187) of the ether which undergoes cleavage to yield the radical (188), a hydroxymethyl equivalent. When these are generated in the presence of a,P-unsaturated esters such as (189) addition takes place affording the adducts (190). Additions to dimethyl maleate were also carried out successfully." ... 

The by-product of these reactions is an amide, which usually precipitates and is easily recovered. However, the stoichiometric production of this is a disadvantage which has limited the industrial use of the system. In principle, acetamide can be dehydrated back to acetonitrile using acid catalysts, but this is relatively difficult. In spite of this drawback, an H202/acetonitrile process for epoxidation is believed to have been used on the full scale [25]. 

An ultrashort mid-IR pulse excited a C-H stretching vibration (-3000 cm ) of neat acetonitrile at 300 K. The loss of C-H stretching energy occurred in 3 ps. Only 1% of that energy was transferred to the C N stretch (2250 cm ), where it remained for -80 ps. Most of the energy was lost from the C-H stretch by the process,... 

Interestingly, at very low concentrations of micellised Qi(DS)2, the rate of the reaction of 5.1a with 5.2 was observed to be zero-order in 5.1 a and only depending on the concentration of Cu(DS)2 and 5.2. This is akin to the turn-over and saturation kinetics exhibited by enzymes. The acceleration relative to the reaction in organic media in the absence of catalyst, also approaches enzyme-like magnitudes compared to the process in acetonitrile (Chapter 2), Cu(DS)2 micelles accelerate the Diels-Alder reaction between 5.1a and 5.2 by a factor of 1.8710 . This extremely high catalytic efficiency shows how a combination of a beneficial aqueous solvent effect, Lewis-acid catalysis and micellar catalysis can lead to tremendous accelerations. 

The cases of pentamethylbenzene and anthracene reacting with nitronium tetrafluoroborate in sulpholan were mentioned above. Each compound forms a stable intermediate very rapidly, and the intermediate then decomposes slowly. It seems that here we have cases where the first stage of the two-step process is very rapid (reaction may even be occurring upon encounter), but the second stages are slow either because of steric factors or because of the feeble basicity of the solvent. The course of the subsequent slow decomposition of the intermediate from pentamethylbenzene is not yet fully understood, but it gives only a poor yield of pentamethylnitrobenzene. The intermediate from anthracene decomposes at a measurable speed to 9-nitroanthracene and the observations are compatible with a two-step mechanism in which k i k E and i[N02" ] > / i. There is a kinetic isotope effect (table 6.1), its value for the reaction in acetonitrile being near to the... 

MejSiCI - Nal - CH3CN as an Efficient and Practical Reducing Agent for Benzoic Alcohols. A typical procedure for the present reduction is as follows To a mixture of MejSiCI (1.54 ml, 12 mmol), Nal (1.8 g, 12 mmol), and acetonitrile (0.6 ml, 12 mmol) was added a solution of 1-phenylethanol (244 mg, 2 mmol) in hexane (2 ml). The mixture was stirred for 24 h at room temperature. Dilution with water, extraction with ether and subsequent isolation process gave ethylbenzene (158 mg) with sufficient purity in 75% yield. ... 

Reversed-phase chromatography is widely used as an analytical tool for protein chromatography, but it is not as commonly found on a process scale for protein purification because the solvents which make up the mobile phase, ie, acetonitrile, isopropanol, methanol, and ethanol, reversibly or irreversibly denature proteins. Hydrophobic interaction chromatography appears to be the least common process chromatography tool, possibly owing to the relatively high costs of the salts used to make up the mobile phases. 

Industrial production is often based on transformation of this laboratory method into a continuous process (10). Another route is acetonitrile [75-05-8] hydration ... 

Because of the large price differential between propane and propylene, which has ranged from 155/t to 355 /1 between 1987 and 1989, a propane-based process may have the economic potential to displace propylene ammoxidation technology eventually. Methane, ethane, and butane, which are also less expensive than propylene, and acetonitrile have been disclosed as starting materials for acrylonitrile synthesis in several catalytic process schemes (66,67). 

Irradiation of ethyleneimine (341,342) with light of short wavelength ia the gas phase has been carried out direcdy and with sensitization (343—349). Photolysis products found were hydrogen, nitrogen, ethylene, ammonium, saturated hydrocarbons (methane, ethane, propane, / -butane), and the dimer of the ethyleneimino radical. The nature and the amount of the reaction products is highly dependent on the conditions used. For example, the photoproducts identified ia a fast flow photoreactor iacluded hydrocyanic acid and acetonitrile (345), ia addition to those found ia a steady state system. The reaction of hydrogen radicals with ethyleneimine results ia the formation of hydrocyanic acid ia addition to methane (350). Important processes ia the photolysis of ethyleneimine are nitrene extmsion and homolysis of the N—H bond, as suggested and simulated by ab initio SCF calculations (351). The occurrence of ethyleneimine as an iatermediate ia the photolytic formation of hydrocyanic acid from acetylene and ammonia ia the atmosphere of the planet Jupiter has been postulated (352), but is disputed (353). 

New Synthesis. Many attempts have been made to synthesize oxaUc acid by electrochemical reduction of carbon dioxide in either aqueous or nonaqueous electrolytes (53—57). For instance, oxaUc acid is prepared from CO2 as its Zn salt in an undivided ceU with Zn anodes and stainless steel cathodes ia acetonitrile containing (C4H2)4NC104 and current efficiency of >90% (53). Micropilot experiments and a process design were also made. 

Economic considerations in the 1990s favor recovering butadiene from by-products in the manufacture of ethylene. Butadiene is a by-product in the C4 streams from the cracking process. Depending on the feedstocks used in the production of ethylene, the yield of butadiene varies. Eor use in polymerization, the butadiene must be purified to 994-%. Cmde butadiene is separated from C and C components by distillation. Separation of butadiene from other C constituents is accomplished by salt complexing/solvent extraction. Among the solvents used commercially are acetonitrile, dimethyl acetamide, dimethylform amide, and /V-methylpyrrolidinone (13). Based on the available cmde C streams, the worldwide forecasted production is as follows 1995, 6,712,000 1996, 6,939,000 1997, 7,166,000 and 1998, 7,483,000 metric tons (14). As of January 1996, the 1995 actual total was 6,637,000 t. 

Separation and Purification. Separation and purification of butadiene from other components is dominated commercially by the extractive distillation process. The most commonly used solvents are acetonitrile and dimethylformarnide. Dimethylacetamide, furfural, and... 

This type of amination by an oxaziridine is assumed to be the key step of a novel process for hydrazine manufacture, in the course of which butanone in solution with ammonia is reacted with hydrogen peroxide and acetonitrile. The smooth formation of oxaziridines from Schiff bases and hydrogen peroxide-nitrile mixtures is as well known as NH transfer from an oxaziridine like (300), suggesting the intermediacy of (300) as the N—N forming agent (72TL633). 

Acrylonitrile. Acrylonitrile is produced by reacting propylene, ammonia, and owgeu (air) in a single flmdized bed of a complex catalyst. Known as the SOHIO process, this process was first operated commercially in 1960. In addition to acrylonitrile, significant quantities of HCN and acetonitrile are also produced. This process is also exothermic. Temperature control is achieved by raising steam inside vertical tubes immersed in the bed [Veatch, Hydrocarbon Proce.ss. Pet. Refiner, 41, 18 (November 1962)]. 

An important biological process is the basis for a general coupling method of aldehydes into symmetncal acyloins, such as BETYROIN. The key catalyst is 5-(2-hydroxyethyl)-4-methyl-l,3-thiazole, an analog of thiamin. Condensation of ketones and aldehydes with excess acetonitrile can be accomplished in a simple way to produce a,p-unsaturated nitriles Cyclohexanone leads to CY-CLOHEXYLIDENEACETONITRILE while benzaldehyde gives CINNA-MONITRILE. 

Fig. 5.P23. The substituent effect in the Menschutkin reaction of 1-arylethyl bromides with pyridine in acetonitrile at 35°C. Circles represent kj for the bimolecular process and squares (for the uni-molecular process.

The principal components of the cut are butene-1, butene-2, isobutylene and butadiene-1,3. Methyl, ethyl, and vinyl acetylenes, butane and butadiene-1,2 are present in small quantities. Butadiene is recovered from the C4 fraction by extraction with cuprous ammonium acetate (CAA) solution, or by extractive distillation with aqueous acetonitrile (ACN). The former process is a liquid-liquid separation, and the latter a vapor-liquid separation. Both take advantage of differences in structure and reactivity of the various C4 components to bring about the desired separation. 

The demand for isoprene for Butyl rubber led to the development of a recovery process for this Cj diolefin. Extractive distillation with acetone was the first process used but it has been replaced with acetonitrile (ACN ). The first step in the process is the fractionation of steam cracker debutanizer bottoms in a conventional two tower system to produce a C5 cut containing 30% isoprene. The first tower rejects C and heavier while the second rejects C4 and lighter materials. 

By using imidazole catalysis, it is possible to get a better understanding of the active forms that water takes in enzymatic processes Thus, at low concentrations m the presence of an enzyme, the water may not be fully hydrogen bonded and therefore more reactive [61] The rate of hydrolysis of p-nitrotrifluoroacetanilide in acetonitrile shows a strong dependence on water concentration at low levels in the presence of imidazole The imidazolium complex is the approximate transition state (equation 60)... 

In order to prepare thin fdms of (SN) on plastic or metal surfaces, several processing techniques have been investigated, e.g., the electroreduction of [SsNs]" salts. Powdered (SN) is prepared by the reaction of (NSC1)3 with trimethylsilyl azide in acetonitrile/ The sublimation of (SN) at 135°C and at pressure of 3 x 10 Torr. produces a gas-phase species, probably the cyclic [SsNs] radical, that reforms the polymer as epitaxial fibres upon condensation/... 

The first part of the process consists in the preparation of methj leneamino-acetonitrile. 

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