Acidic halogenating agent

Use of an excess of the halogenating agent results in halogenation at the 3-position of the oxindole[3,4]. The halogenation and hydrolysis can be carried out as two separate steps. One optimized procedure of this type used NCS as the halogenating agent and it was found that 70% phosphoric acid in 2-mcthoxycthanol was the most effective medium for hydrolysis[2]. If the halogenation is carried out in pyridine, the intermediate is trapped as an... 

V-Chlorosuccinimide [128-09-6] mp 150—151°C, forms orthorhombic crystals and has a chlorine-like odor it is prepared from succinimide and hypochlorous acid (114,115). Because of its powerhil germicide properties, it is used ia disiafectants for drinking water. Like its bromine derivative, it is also a halogenating agent. 

Pentaphenylbismuth is a violet-colored, crystalline compound that decomposes spontaneously after standing for several days in a dry nitrogen atmosphere. With a variety of agents, eg, hydrohahc acids, halogens, and triphenylboron, one phenyl group is cleaved to form quaternary bismuth compounds. 

Fire Hazards - Flash Point Not flammable Flammable Limits in Air (%) Not flammable Fire Extinguishing Agents Use water, foam, or dry chemical on adjacent flres Fire Extinguishing Agents Not to be Used Any agent with an acid reaction (e.g. carbon dioxide or halogenated agents) will... 

In addition to the applications indicated on p. 858. hypohalous acids are useful halogenating agents for Ixjth aromatic and aliphatic compounds. HOBr and HOI are usually generated in silii. The ease of aromatic halogenation increa.ses in the sequence OCl < OBr < Ol and is facilitated by salts of Pb or Ag. Another well-known reaction of hypohalites is their cleavage of methyl ketones to form carboxylates and haloform ... 

The preparation of isothiazolidin-3-one 5-oxide and 5,5-dioxide derivatives of azetidin-3-ones was described (99EUP100069), starting from penicillanic acid sulfoxide amides in the presence of halogenating agents in anhydrous inert solvents or even without them. Through rearrangement and oxidation with conventional methods, compounds 73 could be obtained. For some derivatives the usefulness, as intermediates for the preparation of novel p-lactam analogs or active substances in formulations for antimicrobial therapy, is claimed. 

Chlorination and bromination of chlorins can be carried out with aqueous hydrochloric or hydrobromic acid in the presence of hydrogen peroxide, but also with free chlorine or bromine in solution. Depending on the stoichiometric amount of halogenation agent, mono-or bishalogenated products are selectively formed as in the case of octaethylchlorin 15, Attempts to iodinate chlorins have been unsuccessful. 

Acetoxylation is found to accompany nitration of fairly reactive aromatics by nitric acid in acetic anhydride and gives rise to zeroth-order kinetics76. The electrophile is believed to be protonated acetyl nitrate the formation of which is rate-determining, hence the kinetic order (see p. 37). Acetoxylation can also accompany halogenation by positive halogenating agents in acetic acid solvent, especially in the presence of sodium acetate137, but no kinetic studies have been carried out. 

The acticm of acids, halogens and halogen-releasing agents, as well as phosphorus, sulphur and other inorganic halide reagents was carefully investigated. OYP cal laboratory parameters in the treatment of impure trifluralin with various acids follow. 

The most common preparative procedures involve use of the halogen, usually bromine, in acetic acid. Other suitable halogenating agents include IV-bromosuccinimide, tetrabromocyclohexadienone, and sulfuryl chloride. 

Superior antimicrobial activity in alkaline pH (seawater is always above pH 8), in the presence of nitrogenous organic matter, and due to lower volatility has been documented for bromine antimicrobials3 4. The pKa acid dissociation constants for HOC1 and HOBr are 7.4 and 8.7, respectively the dissociated acids are less effective antimicrobials4,5. Undissociated hypohalous acids are more effective because they are far better halogenating agents compared to the dissociated anion (hypohalite). Table 1 shows the effect of acid dissociation on antimicrobial performance in well-controlled laboratory experiments. 

Halogenating Agents In situ halide oxidation by mammalian white blood cells, fungi, and aquatic plants Stabilized Hypohalous Acids... 

In the presence of strong acid, however, HO—Hal becomes a very powerful halogenating agent due to the formation of a highly polarised complex (15) ... 

Dibromo-l,4-xylene or its 2,5-dichloro derivative is obtained by bromination or, correspondingly, chlorination of 1,4-xylene. It is oxidized to form 2,5-dibro-moterephthalic acid or its dichloro derivative 59. Subsequent reaction with aryl-amine, for instance in the presence of copper acetate, affords 2,5-diarylamino-terephthalic acid 60. It is also possible to replace the halogen atoms stepwise by arylamino moieties [11]. Cyclization to form linear trans-quinacridones, as in the above-mentioned method, is achieved by using acidic condensation agents ... 

Chemical resistance is generally good to limited at room temperature versus dilute bases and weak acids, oils, greases, aliphatic hydrocarbons, and certain alcohols. Resistance is limited to unsatisfactory versus aromatic and halogenated hydrocarbons. Polyesters are attacked by organic and mineral acids, oxidizing agents, concentrated bases, and phenols. 

PVDFs are not sensitive to most strong mineral and organic acids, oxidizing agents, aromatic and aliphatic hydrocarbons, some halogenated solvents, alcohols, bromine, metal salt solutions, or weak bases. 

They are attacked by chlorine water, oxidizing agents, concentrated sulfuric and nitric acids, halogens, and phenols. 

They are attacked to a greater or lesser degree by concentrated bases and certain dilute bases, chlorine water and strong oxidizing agents, concentrated acids, dilute sulfuric and nitric acids, halogens, certain chlorinated solvents, and amines. 

Halotriazoles can act as halogenating agents and A-acyltriazoles can act as acyl transfer reagents. Triazole can be used for the synthesis of peptide bonds and is superior to imidazole in that less racemization is observed. It can also be used to transfer the t-butyloxycarbonyl (t-Boc) protecting group to the nitrogen of amino acids. For details see Polya <84CHEC-I(5)733, p. 786). 

---