Nitrosation, by nitrosyl chloride

Rate coefficients (k, eqn 16) and activation energies for nitrosation by nitrosyl chloride in aqueous solution... 

Nitrosation by Nitrosyl Chloride. The use of nitrosyl chloride in the presence of sodium acetate 8 as a nitrosating agent shows much promise. Both the yield and the quality of the nitrosoacetylamines prepared by this method are. superior to those resulting from the action of nitrous fumes, and the time required for the reaction is reduced from hours to minutes. Moreover, the reaction can be put on a quantitative basis, since a liquid (NOC1) or a solution of the liquid is employed. In this way, the detrimental results due to an excess of the nitrosating agent can be. avoided. 

More recently, rate and equilibrium constants have been determined directly for the nitrosation by nitrosyl chloride of some alcohols in acetic acid using stopped-flow spectrophotometry (Dalcq and Bruylants, 1975). A second order term in [ROH] was noted for the O-nitrosation of methanol (and a corresponding term containing [ROH] for the reverse step), which was not significant for the other alcohols studied, so that the rate eqn(38) represented the kinetics. A mechanism was proposed involving attack by NOCl at the... 

An unusual reaction leading to an a-hydroxyiminophosphonate reported recently is based on 2-(diisopropoxyphosphinyl)propanal, which was nitrosated by nitrosyl chloride to give a nitrosoaldehyde. Hydrolysis of these compounds cleaved off the formyl group and led, through the nitroso tautomer, to the oxime (equation 117). ... 

In cold carbon tetrachloride, a number of ketimines have been nitrosated with nitrosyl chloride. The A-nitrosoketimines exhibit varying degrees of stability. This stability is enhanced in the case of A-nitrosobenzophenonimines by electron-withdrawing substituents on the benzene ring and by the presence of bulky substituents on the ketimine carbon atom. Unhindered A-nitrosoketimines may decompose at room temperature or even below. This observation is considered to be consistent with a low activation energy for the decomposition and a substantial contribution of the 1,4-dipolar structure (III), in Eq. (16), to the ground state. Structures III, IV, and V represent possible resonance structures of the A-nitrosoketimines [64a]. 

Fluoroform has proved resistant to photochemical nitrosation with nitrosyl chloride, but the haloforms CHFaCl and CHFClj have been converted by this technique into chlorodifluoronitrosomethane and dichloro-fluoronitrosomethane in low yield. The same method has been used to convert chloroform into trichloronitrosomethane in low (ca. 15%) yield at 40 °C this nitroso-compound reacts with silver monofluoride to give trifluoronitrosomethane(<2%) and 0-nitroso-AW-bistrifluoromethylhydrox-ylamine (ca. 20%), with silver monofluoride in dimethylformamide to yield trifluoronitrosomethane (<2%), hexafluoroazoxymethane (10-5%), and... 

LI. On the basis of the evidence of trans-nitrosation and on the apparent specific catalysis by hydrochloric acid, a mechanism first proposed by Houben85 has become generally accepted 8 86,87. This involves a reversible de-nitrosation forming the secondary amine and nitrosyl chloride followed by C-nitrosation in ... 

Ketimines were successfully nitrosated by treatment with nitrosyl chloride in cold carbon tetrachloride resulting in the formation of N-nitrosoimines (Scheme 3.25) [201],... 

H)-Naphthalenone, 4,4a,5,6,7,8-HEXAHYDRO-, 46, 80 Nitroacetone, 46, 3 />-Nitrobenzaldehyde, 46, 36 Nitrosation of N-phenylglycine, 46, 96 N-Nitroso-N-phenylglycine, 46, 96 reaction with acetic anhydride to yield 3-phenylsydnone, 46, 96 Nitrosyl chloride, addition to bicyclo [2.2.1]hepta-2,S-diene, 46, TS Nonane, 1,1,3-trichloro-, 46,104 Noriricvclanol, 46, 74 oxidation by chromic acid, 46, 78 NortricyclanOne, 46, 77 Nortricyclyl acetate, 46, 74 from bicyclo[2.2.1]hepta-2,5-dlene and acetic acid, 46, 74 saponification of, 46, 75... 

Instead of diazotation of >-aminostyrene units, the nitrosation of their acetamino derivatives with nitrosyl chloride has been described by Hahn (94), as well as the synthesis of diazoamino compounds. On decomposition these groups furnish active sites for monomer growth, e. g. acrylonitrile. s... 

The 2-hydroxy-2-methoxyoxime 272, prepared by a-nitrosation of the ketone 271 using nitrosyl chloride in dry methanol solution, upon treatment with KOH gives rise to 3-hydroxyimidazole 1-oxide 267 (1977JOC2748). Only one example is reported but the sequence could have a broader preparative potential (Scheme 79). 

The nitrosation is carried out by passing nitrous fumes into an ice-cold solution or suspension of the acetylamine in acetic acid and acetic anhydride, or by adding a solution of nitrosyl chloride to the acetylamine and sodium acetate in acetic acid. The nitroso derivative is precipitated by pouring the solution into ice water and is extracted by the aromatic liquid or filtered and added to the liquid with which it reacts. In the example given, 3-nitrobiphenyl is obtained from m-nitroacetanilide in 83% yield. 

Normal nitroso derivatives which cannot be prepared with nitrous fumes from certain compounds can be formed by means of nitrosyl chloride. In particular, the nitroso derivatives of p-nitroacetanilide and of diacetyl-1,3-phenylenediamine can be prepared.- However, 2,4,6-trinitroacetanilide and 2,5-diethoxydiacetyl-l,4-phenylenediamine have resisted nitrosation even by this method. 

Acyl and perfluoroalkyl diazomethanes react with nitrogen oxides, and a-diazosulfones with nitrosyl chloride or dinitrogen trioxide, to give furoxans. The process is believed to involve nitrosation, followed by loss of nitrogen to form the nitrile oxide which subsequently dimerizes. Nitrosation of dimethylphenacylsulfonium bromide with nitric acid/sodium nitrite gives dibenzoylfuroxan. 

Diazotization in organic solvents allows solid diazonium salts to be isolated. Diazotization can be carried out using an ester of nitrous acid, such as pentyl nitrite, in a solvent such as acetic acid or methanol. A procedure has also been described for isolating diazonium tetrafluoroborates, in excellent yield, by carrying out the diazotization with boron trifluoride etherate and f-butyl nitrite in ether or dichlorometh-ane at low temperature. Another method for the preparation of a variety of diazonium salts in a nonaqueous medium makes use of the chemistry of bis(trimethylsilyl)amines (8). These compounds react in dichloromethane with nitrosyl chloride and other nitrosating agents which are generated in situ. Thus, benzenediazonium chloride was isolated (96%) from bis(trimethylsilyl)aniline. 

N-Nitroso derivatives of secondary amines are transformed into /> nitroso derivatives by the action of hydrogen chloride in alcohol and ether solution (Fischer-Hepp). The conversion is believed to occur through the liberation of nitrosyl chloride followed by nitrosation, viz., ... 

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