With phosgene

A contact insecticide with the trade name Sevin . White solid, m.p. 142 C. It is prepared by reaction of I-naphthol with methyl isocyanate or with phosgene and a base. 

Further nitration of the 2- and 4- isomers yields 2,4-dinitrotoluene, yellow crystals, m.p. 71 "C. This material is reduced to 2,4-di-aminotoluene and treated with phosgene to give 2,4-diisocyanatotoluene, a precursor of polyurethanes. 

Acylation of the Leimgruber Batcho enamines with phosgene followed by methanolysis and reductive cyclization generates methyl indole-3-carb-oxylates[8]... 

The Showa Denka Company practices this reaction with a PX—MX mixture (24), whereas Mitsubishi Gas Chemical Company uses high purity MX first to form the dicyanide (25). In both processes, hydrogenation to the diamine follows. y -Xylenediamine is reacted with phosgene to give / -xylene diisocyanate, which is used in urethane resins (26—28). 

Rea.ctlons, As with other tertiary alcohols, esterification with carboxyUc acids is difficult and esters are prepared with anhydrides (181), acid chlorides (182), or ketene (183). Carbamic esters may be prepared by treatment with an isocyanate (184) or with phosgene followed by ammonia or an amine (185). 

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). 

A variation of this method involves the conversion of the amine into the amine hydrochloride prior to treatment with phosgene. This method has the advantage of producing generally cleaner products by retarding the secondary reaction of the free amine with carbamoyl chloride. 

More convenient is the use of aryl a2ides which are readily converted into isocyanates upon heating in nonreactive solvents via the loss of nitrogen. The latter method is useful for the synthesis of isocyanates with additional substituents which could not be prepared with phosgene (20). 

The reaction of the corresponding diamine of 1,5-dinitronaphthalene with phosgene produces 1,5-naphthalenediisocyanate/ 173-72-6] (41,42). 

Naphthol is mainly used in the manufacture of the insecticide carbaryl (59), l-naphthyl A/-methyicarbamate/ iJ-2j5 - (Sevin) (22), which is produced by the reaction of 1-naphthol with methyl isocyanate. Methyl isocyanate is usually prepared by treating methylamine with phosgene. Methyl isocyanate is a very toxic Hquid, boiling at 38°C, and should not be stored for long periods of time (Bhopal accident, India). India has developed a process for the preparation of aryl esters of A/-alkyl carbamic acids. Thus l-naphthyl methylcarbamate is prepared by refluxing 1-naphthol with ethyl methylcarbamate and POCl in toluene (60). In 1992, carbaryl production totaled > 11.4 x 10 t(35). Rhc ne-Poulenc, at its Institute, W. Va., facihty is the only carbaryl producer in United States. 

Phosphates and siUcates of metals often react with phosgene at elevated temperatures and yield the metal chloride and phosphoms oxychloride or sihcon dioxide. The reaction with ferric phosphate at 300—350°C has been proposed as a synthetic method for phosphoms oxychloride, POCl. ... 

Anhydrous aluminum chloride forms a variety of complexes with phosgene, eg, 3COC12 at low temperatures, 3COC12 at 30°C, and... 

Ammonia reacts vigorously with phosgene. The products are urea, biuret, ammeUde (a polymer of urea), cyanuric acid, and sometimes cyameUde (a polymer of cyanic acid). The secondary products probably arise through the very reactive intermediate carbamyl chloride [463-72-9] NH2COCI (see... 

Hydrazine reacts with phosgene yielding carbohydrazide ... 

This reaction is commercially important because it serves as a basis for the manufacture of polycarbonate. Carboxyhc acids react with phosgene to give acid chlorides (26) (see Carboxylic acids). 

Amides react with phosgene to yield nitriles (qv). Phosgene also can initiate ring opening ... 

The diacid components for the manufacture of poly(y -phenyleneisophthalamide) and poly(p-phenyleneterephthalamide) are produced by one of two processes. In the first, the diacid chlorides are produced by the oxidation of / -xylene [108-38-3] or -xylene [106-42-3] followed by the reaction of the diacids with phosgene [75-44-5]. In the second, process m- or -xylene reacts with chlorine initiated by ultraviolet light to form the m- or Nhexachloroxylene. This then reacts with the respective aromatic dicarboxyUc acid to form the diacid chloride. 

A tme condensation reaction is characterized by elimination of a small molecule when the monomers condense to form the repeating unit. Reacts with phosgene COCl to form the repeat unit shown (see Polycarbonates). 

Primary cycloaUphatic amines react with phosgene to form isocyanates. Reaction of isocyanates with primary and secondary amines forms ureas. Dehydration of ureas or dehydrosulfuri2ation of thioureas results in carhodiimides. The nucleophilicity that deterrnines rapid amine reactivity with acid chlorides and isocyanates also promotes epoxide ring opening to form hydroxyalkyl- and dihydroxyalkylaniines. Michael addition to acrylonitrile yields stable cyanoethylcycloalkylarnines. 

V-Phenylsuccinimide [83-25-0] (succanil) is obtained in essentially quantitative yield by heating equivalent amounts of succinic acid and aniline at 140—150°C (25). The reaction of a primary aromatic amine with phosgene leads to formation of an arylcarbamoyl chloride, that when heated loses hydrogen chloride to form an isocyanate. Commercially important isocyanates are obtained from aromatic primary diamines. 

Phosgenation. The most important reaction of y -toluenediamine is with phosgene [75-44-5] to give toluene diisocyanate TDI (see... 

Commercially, the PMDA mixtures are normally treated with phosgene to produce the corresponding isocyanates. These isocyanate mixtures, commonly called polymeric MDI (PMDI), are sold direcdy and have varied chemical compositions. The 4,4 -MDI can be separated from the PMDI products by distillation or crystallisation (31,32). The amount of 4,4 -MDI that is removed depends on marketing conditions. The residues are also viable commercial products. 

Reaction with Phosgene. This reaction of amino acid esters is used for preparing the corresponding isocyanates, especially lysine diisocyanate [4460-02-0] (LDI). LDI is a valuable nonyellowing isocyanate with a functional side group for incorporation in polyurethanes. 

Formation of N-Carboxy-(X-Amino AeidAnhydride (NCA) (85), NCAs are important as starting materials for amino acid polymers. They are prepared by the reaction of amino acids with phosgene in an aptotic solvent. 

Isocyanate. Lysine has two amino groups in the molecule and dHsocyanate is prepared by reaction with phosgene. Lysine trHsocyanate [69878-18-8] (LTI) is developing on a commercial scale in Japan (244). 

Toluene Diisocyanate. Toluene diisocyanate is the basic raw material for production of flexible polyurethane foams. It is produced by the reaction sequence shown below, in which toluene is dinitrated, the dinitrotoluene is hydrogenated to yield 2,4-diaminotoluene, and this diamine in turn is treated with phosgene to yield toluene 2,4-diisocyanate. 

The reaction of xanthates with phosgene proceeds through the following steps (49,50) ... 

Miscellaneous Disazo Dyes. Another group of disazo dyes is prepared by condensation of two identical or different aminoazo compounds commonly with phosgene, cyanuric chloride, or fumaryl dichloride, the fragments of which act as blocking groups between chromophores. 

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