Hydrocarbons reaction with, phosgene

The reaction with disubstituted formamides and phosphorus oxychloride, called the Vilsmeier or the Vilsmeier-Haack reaction,is the most common method for the formylation of aromatic rings. However, it is applicable only to active substrates, such as amines and phenols. An intramolecular version is also known.Aromatic hydrocarbons and heterocycles can also be formylated, but only if they are much more active than benzene (e.g., azulenes, ferrocenes). Though A-phenyl-A-methyl-formamide is a common reagent, other arylalkyl amides and dialkyl amides are also used. Phosgene (COCI2) has been used in place of POCI3. The reaction has also been carried out with other amides to give ketones (actually an example of 11-14),... 

The reaction of volatile chlorinated hydrocarbons with hydroxyl radicals is temperature dependent and thus varies with the seasons, although such variation in the atmospheric concentration of trichloroethylene may be minimal because of its brief residence time (EPA 1985c). The degradation products of this reaction include phosgene, dichloroacetyl chloride, and formyl chloride (Atkinson 1985 Gay et al. 1976 Kirchner et al. 1990). Reaction of trichloroethylene with ozone in the atmosphere is too slow to be an effective agent in trichloroethylene removal (Atkinson and Carter 1984). 

DOT CLASSIFICATION 6.1 Label Poison SAFETY PROFILE A poison by ingestion, inhalation, skin contact, intraperitoneal, intravenous, and subcutaneous routes. Moderately toxic to humans by inhalation. It can affect the nervous system, liver, spleen, and lungs. An experimental teratogen. Mutation data reported. A severe eye and mild skin irritant. Flammable liquid when exposed to heat, flame, or oxidizers. To fight fire, use alcohol foam, CO2, dry chemical. Violent reaction with chlorosulfonic acid, ethylene diamine, sodium hydroxide. Reacts with water or steam to produce toxic and corrosive fumes. Potentially violent reaction with oxidizing materials. When heated to decomposition it emits highly toxic fumes of CT and phosgene. See also CHLORINATED HYDROCARBONS, 7M.IPHATIC. 

When (253) reacts with phosgene the 1-acyl chloride product (254) can react with amines to give amides (79LA1756X while in a further transfer reaction with ketones the compounds (255) and (256) are produced (Scheme 146) (80H(14)97). Acylation of aromatic hydrocarbons using 1-acylimidazoles in the presence of trifluoracetic acid gives high yields provided that the aryl compounds are electron rich, e.g. p-dimethoxybenzene, thiophene, anisole <80BCJ1638). 

Upon protracted contact with aluminium(III) chloride at higher temperatures, and especially if the aromatic hydrocarbon is itself used as the solvent, the product of the reaction between phosgene and aromatic hydrocarbons is usually the corresponding benzophenone [2026]. Friedel and Crafts [686aa] found that COCI, reacts with benzene in the presence of a stoicheiometric amount of aluminium(III) chloride to give benzophenone ... 

The reaction of phosgene with hydrogen fluoride offers a potentially attractive route to the synthesis of carbonyl difluoride. However, the hydrogen chloride co-product of the reaction, represented in Equation (13.4) has a boiling temperature (-83.1 C) very close to that of COFj (-84.6 "C). In addition, azeotrope formation occurs, so that the two materials are only separated with great difficulty using normal distillation techniques. Separation of the two materials may be affected using aliphatic nitriles (such as ethanenitrile) or aromatic hydrocarbons (such as toluene) in which HCl is more readily absorbed relative to COF j [629,630]. Alternatively, the separation may be affected by adsorption of the HCl onto a metal fluoride, SO 3 or PjOj, which do not react at all readily with the COFj [2069]. 

Since Kharasch reported radical-mediated carboxylation of saturated hydrocarbons with phosgene as a radical trap in the 1940s [39], no successful radical acylation and carboxylation reactions have appeared. In intermolecular radical acetylations, biacetyl was used as a radical trap (Scheme 18) [44]. The addition of an alkyl radical to the carbonyl carbon of biacetyl gives the methyl ketone along with an acetyl radical. 

Reaction of cyanuric chloride with amines to give reactive dyes 2. Sulfonation and nitration of naphthalene at low temperatures 3. Reaction between terephthalic acid and ethylene oxide in a solvent in the presence of dissolved catalysts 4. Manufacture of diisocyanate by reaction between phosgene and hydrochlorides of amines 5. Alkaline hydrolysis of solid esters such as di-/3-chloroelhyl oxalate and nitrobenzoic acid esters Venkatraman (1972) Groggins (1958) Hydrocarbon Proc. Petrol. Refiner (1971) Bhatia et al. (1976) Sharma and Sharma (1969, I970a,b)... 

Carbonyldiimidazoles (e.g. GDI) are prepared in high yield with little by-product formation by the reaction of imidazoles [(un)substituted in the 4- and/or 5-positions] (e.g. imidazole) with phosgene in the presence of a tertiary amine (e.g. tributylamine), which acts as an HCl scavenger. This amine has a lower pKb value than the imidazole. The reaction is performed in an aromatic hydrocarbon solvent (e.g. xylene), from which the product is crystallized. The tertiary amine hydrochloride salt is extracted into water, neutralized with an aqueous solution of an inorganic base (e.g. NaOH), and the free amine is re-extracted into an organic solvent (EtOAc). 

Methylene chloride is one of the more stable of the chlorinated hydrocarbon solvents. Its initial thermal degradation temperature is 120°C in dry air (1). This temperature decreases as the moisture content increases. The reaction produces mainly HCl with trace amounts of phosgene. Decomposition under these conditions can be inhibited by the addition of small quantities (0.0001—1.0%) of phenoHc compounds, eg, phenol, hydroquinone, -cresol, resorcinol, thymol, and 1-naphthol (2). Stabilization may also be effected by the addition of small amounts of amines (3) or a mixture of nitromethane and 1,4-dioxane. The latter diminishes attack on aluminum and inhibits kon-catalyzed reactions of methylene chloride (4). The addition of small amounts of epoxides can also inhibit aluminum reactions catalyzed by iron (5). On prolonged contact with water, methylene chloride hydrolyzes very slowly, forming HCl as the primary product. On prolonged heating with water in a sealed vessel at 140—170°C, methylene chloride yields formaldehyde and hydrochloric acid as shown by the following equation (6). 

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