O-Nitro anisole

Alkaline reduction of o-nitro-anisole leads (as in the case of nitrobenzene) to the hydrazo-compound, which undergoes a benzidine trans-... 

Substituted nitrobenzenes gave similar results on reduction of less than stoichiometric quantities in the absence of added alkali, hydrogen atom-substrate ratios of 3.0 to 4.1 being obtained while cessation of hydrogen absorption occurred at H/Co = 2.0 in all cases. Azoxy and azo compounds were isolated from o-nitrotoluene (H/substrate = 3.9) p-nitrotoluene (H/substrate = 3.2) yielded a mixture of azoxy and hydroxylamine derivatives, the latter believed to be the immediate precursor of the bimolecular product. Reduction of o-nitro-anisole in the presence of added alkali (NaOH, 3.3X cobalt concentration)... 

The effect of a hydroxyl or an alkoxyl group on the ease of alkylation is complex. In some instances, the effect appears to be an activation. For example, although nitrobenzene has not been alkylated, o-nitro-anisole has been converted into the isopropyl derivative in good 3ueld. 

First of all, there are the two products of O-coupling addition of methoxide ion to the diazonium ion, the (Z)- and (jE)-diazo methyl ethers. As discussed in Section 6.2, they are formed in reversible reactions with half-lives of the order of a fraction of a second (Z) to a minute (E). The two diazo ethers are, however, decomposed rapidly to the final dediazoniation products. We show in Scheme 8-47 the products obtained by Broxton and McLeish (1983 b) in the dediazoniation of 4-chloro-3-nitrobenzenedi-azonium ion (8.64) with methoxide ion in CH3OH. The products are 4-chloro-3-nitro-anisole (8.65, 49 9o), 2-chloro-nitrobenzene (8.66, 449o), and 2-nitroanisole (8.67). 

All of these effects are observed when comparing the rates of various electrophilic aromatic substitution reactions. Activating substituents increase the rate of reaction relative to benzene. The rate of reaction for the nitration of anisole, for example, was 9.7 x 10 times faster than nitration of benzene. The reaction of anisole with nitric and sulfuric acids, gave 44% of o-nitroanisole, 56% of p-nitroanisole and < 1% of m-nitro-anisole.2 9 contrasts with reactions involving deactivating substituents, where selectivity for the meta -product is usually very good. Nitration of nitrobenzene, for example, gave 1,3-dinitrobenzene in 94% yield, with only 6% of the ortho product and < 1% of the para product. ... 

Fig. 3. Separation of an o-, m-, p-mixture of nitro-anisole by a clathrate chromatography system using a Wemer-type compound (elution curve)...

Anisole, p-methoxy-. See p-Dimethoxybenzene Anisole, o-methyl-. See o-Methylanisole Anisole, o-nitro-. See o-Nitroanisole Anisole, o-phenyl-. See o-Phenyl anisole Anisole, p-propenyl-, (E) Anisole, p-propenyl-, trans-. See trans-Anethole Anisomycin... 

Synonyms Anisole, o-nitro- Benzene, 1-methoxy-2-nitro- 1-Methoxy-2-nitrobenzene 2-Methoxynitrobenzene 2-Nitroanisole o-Nitrobenzene methyl ether o-Nitrophenyl methyl ether Empirical C7H7NO3 Formula CH3OC6H4NO2 Properties Lt. reddish or amber clear liq. sol. in DMSO, alcohol, 95% ethanol, acetone, ether sol. 

N,N -Diethyl-N,N -diphenylurea Girstrat -Centralite I Girstrat -Ethylcentralite 201-646-8 2-Nitro-1,1 -biphenyl 201-659-9 o-Phenyl anisole 201-662-5 Diphenylacetonitrile 201-663-0... 

Thus, p- xylene yielded 2,5-dichloro-p-xylene. The principal reaction with anisole was also chlorination and with phenol nitration when nitration temperature was low (-80°C) both o- and p- nitrophenols were formed. At room temperature chlorination also occurred yielding 2,4-dichloro-6-nitrophenol and 3,6-dichloro-2-nitro-phenol. 

N itro-5- b rom o-2- d i ozore sore i nol -1 -m eth y I ether, C7H4N304Br mw 274.04, N 15.33% orn-yel crysts, mp 189°, explodes when heated above its mp was obtd from 4-nitro-3,5-dibromo-anisole-diazonium-2-hydroxide by treating with H2SO4 or acetic acid soln Ref Beil 16, (365)... 

Reference 81 also reports the solid phase enthalpies of formation of the isomeric 4- and 5-nitro-2-methoxyanilines, —197 and —232 kJmol-1. These values are disconcertingly disparate. The two isomers should have very nearly identical enthalpies of formation because in both cases there are electron-donating groups para to the nitro group and so there should be comparable stabilization. From equation 18, an estimated value of solid anisole, and the average enthalpy of formation of m- and p-nitroaniline, a calculated enthalpy of formation of the nitro-o-anisidines is ca — 210 kJ mol-1. 

One nitro group of 0-dinitrobenzene and its derivatives is reactive and can be replaced by a mercapto, alkylthio, or sulfo group under the influence of sodium sulfide, sodium thiolates, or sodium sulfite, respectively. For preparative purposes this reaction is, however, restricted to a few examples. o-Dinitro-benzene and sodium sulfide give bis-(0-nitrophenyl) sulfide,492 and trinitro-anisole gives the bis(methoxydinitrophenyl) sulfide.493... 

One other synthetic application of ipso nitroarenium ions can be mentioned. When the mixture of stereoisomeric o-xylene nitro, acetoxy adducts was dissolved in anisole and HaSO, was added. 

The reaction with participation of nitrous acid provides a method for nitration and hydroxylation of aromatic compounds, and for the preparation of m-nitro compounds and derivatives of o-nitrophenol. Unfortunately, the yields are very small and the products difficult to separate in many cases. Of the aromatic compounds used, nitrobenzene and anisole give the best yields of products in reactions with HOONO, correspondingly 8% and 30%. The corresponding yield for benzene, toluene, and chlorobenzene is <6% [22]. 

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