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Organic Air Pollutants
Published in Stanley E. Manahan, Environmental Chemistry, 2022
Aromatic amines are of special concern as air pollutants, especially in the workplace, because some cause urethral tract cancer (particularly of the bladder) in exposed individuals. Aromatic amines are widely used as chemical intermediates, antioxidants, and curing agents in the manufacture of polymers (rubber and plastics), drugs, pesticides, dyes, pigments, and inks. In addition to aniline, some aromatic amines of potential concern are the following:
p-Nitrobenzenesulfonamide in a Three-Phase Slurry Reactor
Published in Dale W. Blackburn, Catalysis of Organic Reactions, 2020
Makarand G. Joshi, William E. Pascoe, Dennis E. Butterfield
Aromatic amines are major intermediates in the manufacture of a wide variety of products such as polymers, antioxidants, herbicides, insecticides, dyes, pharmaceuticals, and photographic chemicals. These amines are usually made by catalytic hydrogenation of corresponding nitro compounds. Batch slurry reactors are the reactors of choice for these reductions. Since there are three different phases present in the reactor and the nitro functions are reduced quite readily, the mass transfer resistances can play an important role in determining the overall rate of the reaction and the selectivity.1-5 Furthermore these reductions are also highly exothermic and a careful consideration has to be given to the heat removal from the reactor at least from the safety viewpoint. Thus it is not surprising that the scale-up of these reactions is often difficult. This motivated us to investigate the interaction of transport processes and the reaction kinetics in these reactions. The main objective of the study was to develop a methodology to evaluate the mass and heat transfer effects in production reactors used for these reductions and suggest ways to improve the efficiency of these reactors and/or develop new reactor strategies to carry out these reductions.
Solvent Exposure and Toxic Responses
Published in Stephen K. Hall, Joana Chakraborty, Randall J. Ruch, Chemical Exposure and Toxic Responses, 2020
Most of the aromatic amines in the free base form are readily absorbed through the skin in addition to the respiratory route. The two major toxic effects are methemoglobinemia and cancer of the urinary tract. Other effects may be hematuria, cystitis, anemia, and skin sensitization. Several of the aromatic amines have been shown to be carcinogenic in humans or animals or both. The most common site of cancer is the bladder, but cancer of the pelvis, ureter, kidney, and urethra do occur.
Aromatic amines equilibrium sorptive interaction with synthesized silica based mesoporous MCM-41: Physicochemical evaluation and isotherm modeling
Published in Journal of Environmental Science and Health, Part A, 2019
Sehaspreet Kaur Toor, Jai Prakash Kushwaha, Vikas Kumar Sangal
Aromatic amines are well known components in wide variety of wastewater including those from synthetic polymer industries, tanneries, oil refining processes and several other chemical process industries (dyes and textile, pesticides, herbicide, adhesives and rubber, pharmaceuticals, etc.).[1] Carcinogenic and mutagenic nature of aromatic amines is well known.[2] Twenty-two types of aromatic amines including 4-chloro-o-toluidine (4-COT) above 30 mg/L in effluents have been restricted by European Union Standards (1907/2006).[3] 4-COT is produced as an intermediate in pesticide industries, and its hydrochloride salt is used in manufacturing of various azo dyes for cotton silk and nylon.[4] Exposure to 4-COT can produce urinary bladder cancer and mutagenic effects in humans.[4,5] Blood-vessel tumors (hemangioma or hemangiosarcoma) in the spleen and adipose tissue in mice have also been reported due to 4-COT exposure.[6]
A comparative examination of acute toxicities of three disazo dyes to freshwater macroinvertebrates Gammarus roeseli (Crustacea: Amphipoda) and Chironomus riparius (Insecta: Diptera)
Published in Chemistry and Ecology, 2021
In the current study, a positive relationship was found to exist between mortality and both exposure period and dye concentration in both bioassays. This result is consistent with general results from various studies; mortality increases with increasing chemical concentration and exposure period [16,19,20,33,44,45]. The LC50 values of the tested dyes in the present study decreased with an increasing exposure period, agreeing with the general pattern of the LC50 values of chemicals [44,46]. The LC50 value is not indicative of an acceptable level of a chemical in the environment but rather is used as an indicator of relative acute toxicity. It is well known that the lower the resultant LC50 value, then the more the acute toxicity of the sample. Therefore, the detected negative correlation between the LC50 value and exposure period for all dyes demonstrates that the toxicity of each dye significantly increases with time. However, the toxicity of dyes 2 and 3 increased more with increasing exposure period than that of dye 1, which was selected as the reference dye. This makes the long-term existence of dyes 2 and 3 in aquatic environments a noteworthy threat for these ecosystems, possibly resulting from the nitro and chloro groups and their effects on the organisms. Therefore, it is possible to state that dyes 2 and 3 (and probably all azo dyes substituted with the nitro and chloro groups) can potentially be of environmental concern and that effluents containing these kinds of azo dyes, depending upon their chemical compositions and degradation products, have to be treated with appropriate treatment processes. It is known that the toxicity is generally not because of the azo dye itself, but because of its degradation products [15]. The azo linkage of an azo dye, the most labile portion, may easily undergo breakdown by azoreductases (widespread enzymes among organisms including various microorganisms and humans) [15,42], resulting in the release of aromatic amines [15]. Many of these aromatic amines exhibit a very high level of acute and chronic toxicity and carcinogenicity in aquatic organisms. Thus, we can suggest that degradation products of these dyes should be analysed in future studies.
Methods for the synthesis of N-aryl sulfonamides from nitroarenes: an overview
Published in Journal of Sulfur Chemistry, 2021
Jingjing Xia, Kehua Zhang, Evan Abdolkarim Mahmood
Sulfonamides, especially N-aryl sulfonamides, are a crucial structural unit in bioactive compounds [1–3], agrochemicals [4], and drugs [5]. Interestingly, up to fifteen currently marketed drugs are N-(hetero)aryl sulfonamide derivatives (Figure 1) [6] that use for the treatment of various types of diseases such as HIV, cancer, heart failure, serious burns, and inflammatory diseases. Traditional methods for the preparation of N-(hetero)aryl sulfonamide mainly rely on the nucleophilic substitution of sulfonylating agents (e.g. sulfonyl halides, sulfinate salts, sulfonic acids) with anilines as the nitrogen source [7–13]. However, most aromatic amines are toxic and may cause serious environmental pollution and safety problems [14]. Another synthetic pathway is the cross-coupling of sulfonamides as nitrogen-based nucleophiles with aryl halides, aryl nonaflates, arylboronic acids, arylhydrazines, and diaryliodonium salts [15–22]. This alternative route offers a straightforward strategy for the fabrication of the titled compounds without the use of aromatic amines. However, this approach is limited by the need for harsh conditions, additional bases and/or ligands, or both [23]. Recently, non-toxic, stable, readily available, and abundant nitroarenes have emerged as a highly attractive nitrogen source for the construction of N-arylsulfonamides without prior reduction into anilines. Despite the remarkable progress that has been achieved since 2015 in this arena, a comprehensive overview has not appeared on this research topic in the literature to date. In connection with our review articles on the synthesis of organosulfur compounds [24–28] and new methodologies in organic synthesis [29–39], in this Focus-Review we will summarize a variety of methods for the construction of N-(hetero)aryl sulfonamides from the corresponding nitro(hetero)arenes. The review is divided into three major sections (Figure 2). The first section will cover reductive cross-coupling reactions of nitroarenes with different sulfonating agents. The second will discuss the reductive coupling of nitroarenes with organometallic nucleophiles via the insertion of sulfur dioxide. The third section focuses exclusively on the synthesis of cyclic sulfonamides from the respective nitroarenes. Of note, special emphasis has been placed on mechanistic aspects of the reactions which, may allow possible new insights into catalyst improvement.