Aromatic compounds reaction with, phosgene

Aromatic and heterocycHc compounds are formylated by reaction with dialkyl- or alkylarylformamides in the presence of phosphoms oxychloride or phosgene (Vilsmeier aldehyde synthesis) (125). The Vilsmeier reaction is a Friedel-Crafts type formylation (126), since the intermediate cation formed by the interaction of phosphoms oxychloride with formamide is a typical electrophilic reagent. Ionic addition compounds of formamide with phosgene or phosphoms oxychloride are also known (127). 

Polycarbonates. Polyarjiates are aromatic polyesters commonly prepared from aromatic dicarboxylic acids and diphenols. One of the most important polyarylates is polycarbonate, a polyester of carbonic acid. Polycarbonate composite is extensively used in the automotive industry because the resin is a tough, corrosion-resistant material. Polycarbonates (qv) can be prepared from aUphatic or aromatic materials by two routes reaction of a dihydroxy compound with phosgene accompanied by Hberation ofHCl(eq. 5) ... 

Long-chain alkyl chlorides can be used lor the synthesis of various amines, while benzyl chloride is used for production of quaternary ammonium compounds. Alkyl chlorides are used for the formation of organometallics, including the Grignard reagents as well as for alkylation of aromatics. One of the important reactions or phosgene is with diamines for production of diisocyunates (polyurethanes). 

Condensation Reactions. Many triam inotriarylmethane dyes can be produced by condensation of Michlers ketone (9) with aromatic amines. The ketone must generally be activated with phosgene or phosphorus oxychloride, whereby a reactive blue chloro compound (10) is formed from the intermediate geminal dichloride. With V-phcnyl-1 -naphthylaminc, for example, (13) reacts to form Victoria blue B (11). 

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). 

Friedel-Crafts reaction of phosgene with heterocyclic aromatic compounds is also difficult to stop at the acid chloride stage. However, under selected conditions, heteroaromatics such as thiophene can be directly acylated to give thiophenecarbonyl chloride [Scheme T9] (Ref. 15) ... 

In principle Ae possibility of introducing a halocarbonyl into aromatic compounds with carbonyl dichloride in the presence of Lewis acids exists. In practice it is difficult to stop the reaction after the first electrophilic substitution, because the reaction piquets themselves can react further to give ketones. However, there are exceptions. Thiophene reacts with phosgene in the presence of aluminum trichloride to give 2-chlorocarbonylthiophene almost quantitatively. ... 

Ureas and Carbonates. Reagent (1) may be used as a direct replacement for the highly toxic Phosgene in reactions with alcohols and amines. Reaction of (1) with two equivalents of a primary aliphatic or aromatic amine at room temperature rapidly yields a symmetrical urea (eq 9). If only one equivalent of a primary amine is added to (1), then the imidazole-Al-carboxamide (4) is formed (eq 10). These compounds can dissociate into isocyanates and imidazole, even at room temperature, and distillation from the reaction mixture provides a useful synthesis of isocyanates (eq 10).7 Secondary amines react only at one side of (1) at room temperature, again giving the imidazole-Al-carboxamide of type... 

An amorphous thermoplastic derived from the direct reaction between aromatic and aliphatic dihydroxy compounds with phosgene or by the ester exchange reaction with appropriate phosgene-derived precursors. Highest impact resistance of any transparent plastic. It is transparent and can be injection molded, extruded, thermoformed, or blow molded (esp. branched PC). 

The Vilsmeier-Haack reaction leads to the formation of aromatic aldehydes starting from reactive aromatic compounds. The usual reagent combination is phosphoryl chloride or phosgene together with V-methylformanilide (MFA) or VA -dimethyl-formamide (DMF) [139,140]. First, a V,V-dimethyliminium salt, e.g. 63, is formed which, after basic hydrolysis, gives carbaldehyde. 

Attempts have been made to develop methods for the production of aromatic isocyanates without the use of phosgene. None of these processes is currently in commercial use. Processes based on the reaction of carbon monoxide with aromatic nitro compounds have been examined extensively (23,27,76). The reductive carbonylation of 2,4-dinitrotoluene [121 -14-2] to toluene 2,4-diaLkylcarbamates is reported to occur in high yield at reaction temperatures of 140—180°C under 6900 kPa (1000 psi) of carbon monoxide. The resultant carbamate product distribution is noted to be a strong function of the alcohol used. Mitsui-Toatsu and Arco have disclosed a two-step reductive carbonylation process based on a cost effective selenium catalyst (22,23). 

Over the course of their collaboration they extended the scope of the use of catalytic aluminium chloride to a wide variety of organic reactions (1) reaction of alkyl, acyl chloride, and unsaturated compounds with aliphatic and aromatic hydrocarbons (2) reactions of acid anhydrides, oxygen, sulfur, sulfur dioxide, carbon dioxide, and phosgene with aromatic hydrocarbons (3) cracking of aliphatic and aromatic hydrocarbons, and (4) polymerization... 

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