Dioxide discovery

Francotte P, Goffin E, Fraikin P et al (2010) New fluorinated 1, 2, 4-benzothiadiazine 1, 1-dioxides discovery of an orally active cognitive enhancer acting through potentiation of the 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid receptors. J Med Chem 53 1700-1711... 

Many analogues of saccharin have been synthesized since its discovery. With the exception of one compound, thieno[3,4-i/ isothiazolone dioxide [59337-79-0] lOOOX, this effort has not generated more potent compounds. Acesulfame-K could be considered a ring-modification derivative of saccharin, however. 

Penam Sulfone B-Lactamase Inhibitors. Natural product discoveries stimulated the rational design of p-lactamase inhibitors based on the readily accessible penicillin nucleus. An early success was penicillanic acid sulfone, (2(5)-cis)-3,3-dimethyl-7-oxo-4,4-dioxide-4-thia-l-a2abicyclo [3.2.0]heptane-2-carboxylic acid [68373-14-8] (sulbactam) (25, R = = H, R" = R" = CH ), CgH NO S. The synthesis (118), microbiology (119—121),... 

In the late 1980s, however, the discovery of a noble metal catalyst that could tolerate and destroy halogenated hydrocarbons such as methyl bromide in a fixed-bed system was reported (52,53). The products of the reaction were water, carbon dioxide, hydrogen bromide, and bromine. Generally, a scmbber would be needed to prevent downstream equipment corrosion. However, if the focus of the control is the VOCs and the CO rather than the methyl bromide, a modified catalyst formulation can be used that is able to tolerate the methyl bromide, but not destroy it. In this case the methyl bromide passes through the bed unaffected, and designing the system to avoid downstream effects is not necessary. Destmction efficiencies of hydrocarbons and CO of better than 95% have been reported, and methyl bromide destmctions between 0 and 85% (52). 

Organic fluorine as a separate industry that began in the late 1920s with the discovery by Midgle of fluorocarbons for use as refrigerants. Ammonia was unsuitable because of the hazard and unpleasant smell from minute leaks. Sulfur dioxide had similar problems. The best refrigerant was... 

Historical Introduction and Perchlorates in General History. The early history of perchlorates and the perchlorate mdustryhas been thoroughly discussed (Refs 12 14, p 2), so it will be only briefly reviewed here. Early exptl work on chlorates and perchlorates was closely tied to the discovery and identification of Cl. Several workers, notably Priestly, Lavoisier, and Scheele reported the isolation of volat liqs and gases which probably were oxides or oxyacids of Cl, but they failed to identify and characterize the compds isolated. Scheele, for example, treated muriatic ac (HCl) with Mn dioxide and obtained a volat liq which he called muriatic ac derived of its phlogiston (Ref 14, p3). The first perchlorate definitely identified was the K salt which was prepd by Stadion in 1816 by the thermal decompn of K chlorate (Ref 2). From this he prepd a hydrate of perchloric ac by heating the K salt with sulfuric ac (Ref 3). Pure (anhyd) perchloric ac was first prepd by Roscoe in 1862 by distn of the hydrated ac (Ref 4)... 

Transketolase (TKase) [EC 2.2.1.1] essentially catalyzes the transfer of C-2 unit from D-xylulose-5-phosphate to ribose-5-phosphate to give D-sedoheptulose-7-phosphate, via a thiazolium intermediate as shown in Fig. 16. An important discovery was that hydroxypyruvate works as the donor substrate and the reaction proceeds irreversibly via a loss of carbon dioxide (Fig. 17). In this chapter, we put emphasis on the synthesis with hydroxypyruvate, as it is the typical TPP-mediated decarboxylation reaction of a-keto acid. ... 

The reaction of peroxynitrite with the biologically ubiquitous C02 is of special interest due to the presence of both compounds in living organisms therefore, we may be confident that this process takes place under in vivo conditions. After the discovery of this reaction in 1995 by Lymar [136], the interaction of peroxynitrite with carbon dioxide and the reactions of the formed adduct nitrosoperoxocarboxylate ONOOCOO has been thoroughly studied. In 1996, Lymar et al. [137] have shown that this adduct is more reactive than peroxynitrite in the reaction with tyrosine, forming similar to peroxynitrite dityrosine and 3-nitrotyrosine. Experimental data were in quantitative agreement with free radical-mediated mechanism yielding tyrosyl and nitric dioxide radicals as intermediates and were inconsistent with electrophilic mechanism. The lifetime of ONOOCOO was estimated as <3 ms, and the rate constant of Reaction (42) k42 = 2 x 103 1 mol 1 s 1. 

The discovery of supercritical fluids occurred in 1879, when Thomas Andrews actually described the supercritical state and used the term critical point. A supercritical fluid is a material above its critical point. It is not a gas, or a liquid, although it is sometimes referred to as a dense gas. It is a separate state of matter defined as all matter by both its temperature and pressure. Designation of common states in liquids, solids and gases, assume standard pressure and temperature conditions, or STP, which is atmospheric pressure and 0°C. Supercritical fluids generally exist at conditions above atmospheric pressure and at an elevated temperature. Figure 16.1 shows the typical phase diagram for carbon dioxide, the most commonly used supercritical fluid [1]. 

The reaction in water at pH 7.4 has been much studied since the discovery of the importance of nitric oxide. The products are as for the thermal and photochemical reactions, except that the final product is nitrite ion. This is to be expected since nitric oxide in aerated water at pH 7.4 also yields quantitatively nitrite ion25, by it is believed the series of equations 7-9, which involves oxidation to nitrogen dioxide, further reaction to give dinitrogen trioxide which, in mildly alkaline solution, is hydrolysed to nitrite ion. Under anaerobic conditions it is possible to detect nitric oxide directly from the decomposition of nitrosothiols using a NO-probe electrode system26. Solutions of nitrosothiols both in... 

At least from the time of van Helmont on, the chemists when separating and describing gases usually examined the effect of the gases on animals and plants. Lavoisier (1777) understood that aerobic respiration is the process in which oxygen is consumed and carbon dioxide is produced, shortly after the discovery of oxygen (1771). However, it took about half a century to make aerobic respiration more comprehensible from a physical point of view (Joule 1843 Mayer 1845 and many others). 

Since the discovery of photoelectrochemical splitting of water on titanium dioxide (TiOj) electrodes (Fujishima and Honda, 1972), semiconductor-based photocatalysis has received much attention. Although TiO is superior to other semiconductors for many practical uses, two types of defects limit its photoeatalytic activity. Firstly, TiO has a high band-gap (E =3.2 eV), and it can be excited only by UV light (k < 387 nm), which is about 4-5% of the overall solar spectmm. Thus, this restricts the use of sunlight or visible light (Kormann et al., 1988). Secondly, the... 

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