Aryloxy-nitro

Phenol B.P. M.P. Bromo Com. pound Acetate Benzoate p-NItro benzoate 3 5 D. nltro- benzoate Aryloxy- acetic Acid NN-DI- phenyl- carba- mate N-O- naphthyl carba- mate p-Tolu- enesul- phonate 2 4- Dlnltro- phenyl Ether... 

Solvent for Displacement Reactions. As the most polar of the common aprotic solvents, DMSO is a favored solvent for displacement reactions because of its high dielectric constant and because anions are less solvated in it (87). Rates for these reactions are sometimes a thousand times faster in DMSO than in alcohols. Suitable nucleophiles include acetyUde ion, alkoxide ion, hydroxide ion, azide ion, carbanions, carboxylate ions, cyanide ion, hahde ions, mercaptide ions, phenoxide ions, nitrite ions, and thiocyanate ions (31). Rates of displacement by amides or amines are also greater in DMSO than in alcohol or aqueous solutions. Dimethyl sulfoxide is used as the reaction solvent in the manufacture of high performance, polyaryl ether polymers by reaction of bis(4,4 -chlorophenyl) sulfone with the disodium salts of dihydroxyphenols, eg, bisphenol A or 4,4 -sulfonylbisphenol (88). These and related reactions are made more economical by efficient recycling of DMSO (89). Nucleophilic displacement of activated aromatic nitro groups with aryloxy anion in DMSO is a versatile and useful reaction for the synthesis of aromatic ethers and polyethers (90). 

These are arranged alphabetically according to the atom attached to the ring carbon, halogen, nitrogen (amino, nitro, etc.), oxygen (alkoxy, aryloxy, hydroxy, phosphoryloxy, sulfonyloxy, etc.), and... 

In basischer Pufferlosung lassen sich bei -1 V aus Nitro-alkoxy(aryloxy)-benzolcn se-lektiv die Hydroxylamine herstellen in schwach saurem Milieu (Acetatpuffer, bei -1,6 V) erhalt man Amine. In starker saurem Milieu entstehen aus den 4-AIkoxy-Derivaten unter Atherspaltung Amino-phenole6 ... 

Nitro-l-arso- 686 Nitro-aryloxy- 684 4-Nitro-l-azido- 566 4-Nitro-l-benzyl-... 

The displacement of both halides and nitro groups from polynitroarylenes has been covered in Sections 4.8.1 and 4.8.2. The centres of low electron density induced by electron-withdrawing nitro groups also allow the displacement of many other groups, including hydrogen, alkoxy, aryloxy, sulfonate ester etc. 

Die basenkatalysierte Umsetzung kann auch in Nitrobenzol mil Pyridin als Katalysator [Her-stellung von mehreren 1-(3-Aryloxy-2-hydroxy-propyl)-2-methyl-4-nitro-imidazo-len 38-58%]87t, ohne Losungsmittel mit Kaliumcarbonat als Katalysator [l-(3-ChIor-2-hydroxy-propyl)-2-methyl-4-nitro-imidazol 60%]872 oder in Ethanol mit Natriumhydroxid als Katalysator [l-(2-Hydroxy-ethyl)-2-methyl-4-nitro-imidazol 100%]873 durchgefuhrt we.r-den. Statt Oxiran kann auch 2-Oxo-l,3-dioxolan eingesetzt werden. Dabei entstehen ohne Katalysator bei 160° die 1,4-Regioisomeren [z. B. 2,5-Dimethyl-l-(2-hydroxy-ethyl)-4-nitro-imidazol 60%]874... 

More attention has been paid to the replacement of the nitro groups in TNB [22, 23] for aryloxy groupings. In fact one, two or all nitro groups in TNB can be replaced with aromatic nucleophiles in accordance with Scheme 4.7. 

The methoxide ion has also been found to attack position 5 of 4-nitro-7-methylbenzofurazan to give adduct 168 (X = Me). By analogy with the kinetic behavior a similar reaction has been assumed for other members of the series (7-X = OMe, SMe, SPh, S02Ph).210 Further evidence for the formation of 5-adducts in this series had been provided by a preliminary, nonproductive step of the base hydrolysis of a 4-nitro-7-aryloxy-benzofurazan derived from lysozyme.2"... 

Aryloxy groups are more resistant to rearrangement (unless nitro-activation of the aryl group is present) however, under forcing conditions the reaction (843 — 844) forms the basis for a synthetic technique for converting a phenol into an amine. 

The reactions of the homocyclic ring of benzofuroxans, which are described in detail in Section 4.22.3.3, provide access to numerous derivatives. Nucleophilic displacement of halides is facile when activating nitro groups are present, allowing alkoxy, aryloxy, thio and amino groups to be introduced. Electrophilic substitutions, e.g. nitration, are also valuable. Further transformations may also be performed on benzo-ring substituents. Such modifications include acetoxy to hydroxy acetamido to amino and acyl halides to esters and amides. Some reactions of the substituents of monocyclic furoxans allow hetero-substituted analogues of benzofuroxans to be prepared. For example, pyridazinofuroxans are formed by condensation of diacylfuroxans with hydrazine. 

The same is true for halogens (bromine in most cases), hydroxy-, aryloxy-, or nitro group. The reaction of 4-hydroxycumarines with hydroxylamine proceeds in the same way (Scheme 2.61) [167, 419],... 

Aryloxy- and acyloxycyclopropanes are occasionally made by the diazoalkane plus alkene route and a number of nitro- and dialkoxyphosphanylcyclopropanes can be made in this way. In these syntheses, where the intermediate 4,5-dihydro-3f/-pyrazole has a heteroatom substituent X, elimination of HX giving pyrazole products often contributes a significant side reaction. Hence the diazomethane plus vinylsulfone adduct 34 thermally eliminated 4-toluenesulfinic acid and no cyclopropane was produced. ... 

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