Bromine nitrate

Our objective In this paper is to illustrate the methods for functionalizing poly(arylene ether sulfone). Particular attention will be paid to bromination, nitration, aminatlon, chloromethyl-ation, and aminomethylatlon of 1 and its corresponding model compound. 

Selection of appropriate conditions to modify polymers is facilitated by preliminary studies with well designed model compounds. The work with model systems is critical when studying condensation polymers because the main chain linkages have proved to be remarkably labile under certain conditions. Condensation of 4-chlorophenyl phenyl sulfone with the disodium salt of blsphenol-A yields 2,2-bis[4 -(4"-phenylsulfonylphenoxyl)phenyl] propane, T, an excellent model for the poly(arylene ether sulfone) substrate. Conditions for quantitative bromination, nitration, chloro-methylation, and aminomethylation of the model compound were established. Comparable conditions were employed to modify the corresponding polymers. 

TL5981>. The proposed mechanism involves the oxidation of the amine to an imine, tautomerization to an enamine, and a sequence of nucleophilic attacks on the pyridazine rings followed by oxidation steps. The oxidant of choice is (bispyridine)silver permanganate <1982TL1847>, which is easily prepared, mild in action, and is soluble in organic media. If R1 = H in the product 77, electrophilic substitution (e.g., bromination, nitration, Mannich, and Vilsmeier-Haack-Arnold reactions) occurs at this position. 

N. CHLORINE NITRATE (C10N02) AND BROMINE NITRATE (BrONO,)... 

Chlorine nitrate and bromine nitrate are recognized as key species in the chemistry of the stratosphere. In... 

The photochemistry of bromine nitrate is expected to have similar reaction channels ... 

Deters, B., J. P. Burrows, and J. Orphal, UV-Visible Absorption Cross Sections of Bromine Nitrate Determined by Photolysis of Br0N02/Br2 Mixtures, . /. Geophys. Res., 103, 3563-3570 (1998). 

Chlorine and bromine nitrate serve as temporary reservoirs for chlorine and bromine, taking them out of their ozone destruction cycles. (While theoretical studies suggest that other forms of bromine such as 02Br0N02 could in principle also act as reservoirs (Lee et al., 1999a, 1999b), there is no evidence at the present time that these are important under atmospheric conditions.)... 

Analogous to chlorine chemistry, the formation of bromine nitrate represents the major short circuit in its ozone destruction cycle ... 

Several reactivity parameters adopted from theoretical chemistry have been used to predict the position at which electrophilic reagents will attack higher aromatics l37). The applicability of such parameters to the non-planar hexahelicene was studied qualitatively in bromination, nitration and acetylation reactions 169), and in a quantitative way in the protiodetritiation of the eight monotritiohexahelicenes 170). 

These new chelate systems were brominated, nitrated, and thiocyanogenated under conditions analogous to those previously described for the acetylacetonates. Chelates XL and XLI and their substitution products were found to be more easily degraded than the acetylacetonate, presumably because the oxygen donor atoms... 

Among tetraazapentalenes, early work by Pfleger et a/.350 on 2,6-dimethyl-y-triazolo[2,l-a]-y-triazole 447 showed that mono- and di-substituted products were formed. Bromination, nitration, and benzoyl-ation lead to 3,7-disubstitution, whereas 3-monosubstitution resulted from nitrosation, acetylation, carbethoxylation, and diazotization. Iodin-... 

The 5,6-dihydrodibenz[c,e][l,2]azaborine system has been chlorinated, brominated, nitrated and acetylated. Chlorination of (114 R = Me) with gaseous chlorine gave the 4-chloro derivative as the main product. Chlorination of (114 R = OH) gave the 2,4-dichloro derivative in 60% yield, but no monochloro compound was isolated. Thus it was not possible to differentiate between the reactivities of positions 2 and 4. Chlorination with a solution of chlorine in an organic solvent might give information but was not performed. Trichlorination of (114 R = OH) gave the 2,4,8-trichloro compound. 

Aromatic compounds react mainly by electrophilic aromatic substitution, in which one or more ring hydrogens are replaced by various electrophiles. Typical reactions are chlorination, bromination, nitration, sulfonation, alkylation, and acylation (the last two are Friedel-Crafts reactions). The mechanism involves two steps addition of the electrophile to a ring carbon, to produce an intermediate benzenonium ion, followed by proton loss to again achieve the (now substituted) aromatic system. 

PHA457). Thieno[2,3-d]pyrimidine 89c was brominated, nitrated, and formylated at position 6 to give the 6-bromo, 6-nitro, and 6-formyl derivatives 89d, respectively (90JHC717). 

Electrophilic substitution (bromination, nitration) of 2-substituted 1,2,3,6,7,116-hexahydro-4//-pyrazino[2,l -a]isoquinolin-4-ones occurred on the aromatic moiety to give either 11- or 8-substituted derivatives the site was not determined (76GEP2441261). The nitro group was reduced to an amino group, which was alkylated, acylated, and converted to different groups via a diazonium group, and involved in diazonium coupling. 

We started this chapter by comparing phenols with enols (Ph-enol is the phenyl enol) and now we return to them and look at electrophilic substitution in full detail. You will find that the reaction is much easier than it was with benzene itself because phenols are like enols and the same reactions (bromination, nitration, sulfonations, and Friedel-Crafts reactions) occur more easily. There is a new question too the positions round the phenol ring are no longer equivalent—where does substitution take place ... 

The mercuration of aromatic compounds is of sufficiently general applicability to be classed with such processes as bromination, nitration, and sulfonation, and is particularly easily carried out in the case of phenols and amines. 

In the gas phase, the N-O bonds of chlorine and bromine nitrate are shorter and the O-X bonds longer than in the crystal structure. In the solid state of the halogen nitrates, as for the nitrosyl halides, the contribution of the ionic X+ NOs" structure is higher. This makes the N-O bond shorter and the O-X bond longer. The crystal structures can be considered as adducts of the halogen oxide XO- and the N02- radicals. 

Bromine nitrate reacts with N2O5 to form an adduct. 

Bromine nitrate disproportionates to bromine, oxygen, and N2O5 at 273 K i ... 

Metal /3-diketonates, particularly acetylacetonates, will undergo electrophilic substitution at the central methine carbon atom in a similar way to aromatic compounds. Known reactions of this sort include bromination, nitration, acylation, and the Mannich reaction. 

Treatment of 2,9-dibromophenanthrene with Pt (Et3P)4 followed by bromine-nitrate exchange gave the desired 60° tecton, 2,9-6/i [/ra 5 -Pt(PEt3)2(N03)]phenanthrene, which with different linear connectors afforded a series of self-assembled supramolecular triangles <03JA5193>. A series of related binuclear metallomacrocycles [Cd(N03)2L]2, where L is an angular exo-bidentate, such as 4-(4 -pyridinyl)(2-pyridinylethynyl) benzene, have been reported... 

Pyridine is only brominated, nitrated or sulfonated under vigorous conditions (Scheme 4.24) with reaction occurring at the least deactivated 3-position. Pyridine does not undergo Friedel-Crafts alkylation or acylation. In many cases the electrophile attacks the nitrogen first to form a pyridinium salt, which is even less reactive towards electrophiles. 

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