Nitration nitryl chloride

With BCI3, Olah and Kuhn obtained a smaller amount of nitrated product and considerable ring chlorination SbFs is also an active catalyst for the nitryl chloride nitration of aromatics BFj was found to be inactive as a catalyst. The following yields were obtained upon nitration of the aromatics using TiCl4 as catalyst benzene, 88% toluene, 81.5% ethylbenzene,... 

According to Urbafiski (Ref 74, Chapt 2), this order seems to require some alteration. For example, nitryl chloride has been found to be a definitely weaker nitrating agent than nitric acid and should have been placed before it. The nitronium ion, N02+, occurs in many mixed acid compns... 

A novel, mild system for the direct nitration of calixarenes has been developed using potassium nitrate and aluminum chloride at low temperature. The side products of decomposition formed under conventional conditions are not observed in this system, and the p-nitro-calixarenes are isolated in 75-89% yields.17 Such Friedel-Crafts-type nitration using nitryl chloride and aluminum chloride affords a convenient system for aromatic nitration.18 Nitryl chloride was previously prepared either by the oxidation of nitrosyl chloride or by the reaction of chlorosulfonic acid with nitric acid. However, these procedures are inconvenient and dangerous. Recently, a mixture of sodium nitrate and trimethysilyl chloride (TMSC1) has been developed as a convenient method for the in situ generation of nitryl chloride (Eq. 2.6). 

Nitropropane Nitrosyl fluoride Nitrosyl perchlorate Nitrourea Nitrous acid Nitryl chloride Oxalic acid See under Nitromethane chlorosulfonic acid, oleum Haloalkenes, metals, nonmetals Acetones, amines, diethyl ether, metal salts, organic materials Mercury(II) and silver salts Phosphine, phosphorus trichloride, silver nitrate, semicarbazone Ammonia, sulfur trioxide, tin(IV) bromide and iodide Furfuryl alcohol, silver, mercury, sodium chlorate, sodium chlorite, sodium hypochlorite... 

The nitration reagents (NO2 Y) for electrophilic aromatic nitration span a wide range and contain anions Y such as nitric acid (Y = OH-), acetyl nitrate (Y = OAc-), dinitrogen pentoxide (Y = NO3-), nitryl chloride (Y = Cl-), TV-nitropyridinium (Y = pyridine) and tetranitromethane [Y = C(N02)3-]. All reagents contain electron-deficient species which can serve as effective electron acceptors and form electron donor-acceptor (EDA) complexes with electron-rich donors including aromatic hydrocarbons107 (ArH, equation 86). Excitation of the EDA complexes by irradiation of the charge-transfer (CT) absorption band results in full electron transfer (equation 87) to form radical ion... 

Nitryl chloride and tetranitromethane also At-nitrate amines. However, competing At-nitrosation is a particular problem and results from a redox reaction between the nitrating agent and the amine. 

Deville first synthesized dinitrogen pentoxide in 1849 by reacting silver nitrate with chlorine gas. This reaction probably involves the initial formation of nitryl chloride and, accordingly, dinitrogen pentoxide can also be formed from the reaction of nitryl chloride or nitryl fluoride with a metal nitrate. These reactions are more of theoretical interest than of any practical value. 

Nitryl chloride is used as a nitrating agent in organic synthesis. For example, benzene may be converted to nitrobenzene. The compound also is a chlorinating agent in many preparative reactions. 

An older preparation method involves passing dry chlorine gas slowly over dry silver nitrate heated to about 100°C. The gaseous reaction products are allowed to cool to low temperature. After several hours, nitryl chloride condenses to a pale yellowish-brown liquid. Chlorine is removed by purging with CO2. 

Nitryl chloride reacts with many organics forming their nitro derivatives. Such Friedel-Crafts nitration is catalyzed by a Lewis acid, such as AICI3. An example is nitration of benzene to nitrobenzene ... 

Nitryl chloride reacts with acetic anhydride forming acetyl chloride and acetyl nitrate ... 

Alkaline salts of nitramines arc oxidized by nitryl chloride to products possessing nitrogen in the highest oxidation state, i.e. the nitrate group.255 The free nitramines afford the nitrates in very low yields. 

It was found by Steinkopf and Kiihnel [106] that the so-called nitryl chloride is an agent that both nitrates and chlorinates aromatic hydrocarbons. However, the reaction could be selective. Thus, only o- nitrophenol was formed when nitryl chloride interacted with phenol below room temperature, but at room temperature 2,4-dichloro-6-nitrophenol was obtained. Naphthalene was chlorinated and nitrated simultaneously to give a- nitro- and a- chloro-naphthalene. 

Goddard and co-workers [108-111] found that nitryl chloride in various solvents at room temperature and below (-10°C) chlorinates, rather than nitrates, toluene, m- and p- xylene, and mesitylene, though not benzene. 

Steinkopf and Kuhnel [106] also examined the action of nitryl chloride on ethylene and reported that only 1,2-dichloroethane was formed. Petri [112] however reported the formation of l-chloro-2-nitroethane (with 45% yield) and 2-chloro-ethyl nitrate (35% yield). Ville and DuPont [113] confirmed the formation of l-chloro-2-nitroethane (50% yield) and Goddard [111] confirmed the results of Petri. Price and Sears [107] obtained 2-chloro-l-nitropropane from propane. 

Finally T. Urbanski and Siemaszko [114] used nitryl chloride in the gas phase to O-nitrate cellulose. They obtained a stable product containing 12.2% N. 

Nitryl chloride reacts with zinc, mercury, and bismuth to form mixtures of the metal chlorides and nitrates, but does not react with copper, magnesium, iron, aluminum, or tin at 243 K. In the reaction with ammonia, nitryl chloride acts as a source of positive chlorine ... 

Nitration Acetone cyanohydrin nitrate. Acetyl nitrate. /-Amyl nitrate. Cupric nitrate-Acetic anhydride. Dinitrogen pentoxide. Dinitrogen tetroxide. Dinitrogen tetroxide-Boron trifluoride. Nitronium tetrafluoroborate. Nitryl chloride. Polyphosphoric acid-Nitric acid. Potassium f-butoxide-Amyl nitrate. Tetranitromethane. 

Nitryl chloride, formed from peroxynitrite and HOCl is also capable of nitrating, chlorinating and hydroxylating tyrosine [ 116]. However, the reduction of nitrotyrosine by hypohalous acid has also been demonstrated. Several recent studies indicate that peroxynitrite can lead to generation of both nitrated and hydroxylated phenylalanine residues. The formation of 3-nitrotyrosine and 4-nitrophenylalanine was favoured over the hydroxylation reaction when phenylalanine was treated with peroxy nitrite in vitro [117]. 

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