Oxidation nitrogen addition

Harmata et al. have developed a tandem Sonogashira/nitrogen-addition reaction of acetylenes 261 to sulfonamide 262 to prepare S(vi)-oxidized compounds 263 and 264 (Scheme 36) <20050L143>. When R = alkyl (e.g., Pr"), the 1,2-thiazine 263 is the major product (70%) formed via a endocyclization process, along with a minor amount (20%) of exocyclized product 264, while the five-membered ring product 264 (81%) is preferred when R= Ph. 

These adsorbates can be reduced to ammonia and oxidized to nitrogen. In contrast to the adsorbates of the other compounds, adsorbed nitrite can also be reduced to nitrogen oxides (in addition to ammonia). The combination of cyclic voltammetry (CV) and on-line mass spectrometry (MS) has proved that the adsorbates do not consist solely of triple bonded nitrogen. 

A related approach to the synthesis of triazolopyridone 18 has been used in the formation of 5- and 6-HOAt <20000L2253>. Treatment of a nitrophenylhydrazine with hydrazine hydrate affords the corresponding triazolopyr-idine A -oxide, and addition of acid and subsequent manipulations afford the A -hydroxytriazolopyridine unfortunately, no yields were reported for these reactions (Scheme 2). The 6-isomer was prepared in a similar manner however, in this case protection of the pyridine nitrogen as the A -oxide was not required. 

The solvents that are used for extraction of chlorophylls from leaves or other biological samples are similar to those used for HPLC (unit F4.4). For example, leaves are usually ground in the presence of acetone to extract chlorophylls. After filtration, the solvent is evaporated in vacuo or under a stream of nitrogen (but not air, to avoid oxidation). One additional purification step prior to HPLC (applicable to both Basic Protocols 1 and 2) is to dissolve the chlorophyll residue in hexane and then wash the hexane with water/methanol (1 1 v/v). The hexane may be removed prior to HPLC or simply diluted with mobile phase prior to analysis. 

Poly(l,4-phenylene Ditellurium)1 Under nitrogen, a solution of 1 mol of 1,4-dibromobenzene is cooled to — 15° with stirring, a solution of 22 mol of butyl lithium in hexane is added dropwise followed by 1 mol of finely ground tellurium, and the mixture is stirred at 20° until all of the tellurium has dissolved. To this mixture is added 2 mol of butyl lithium followed by 1 mol of powdered tellurium. When all of the tellurium has dissolved, 2 mol of water and then 2 mol of triethylaminc arc added. The resultant tellurolate is oxidized by addition of an aqueous solution of potassium hexacyanoferrate(Ill) yield 54% reddish-brown, amorphous powder. 

This is followed by the attack of the alcohol on the mesomeric cation (41). The next step involves an intramolecular redox reaction, in which the nitrogen is reduced and the ring oxidized. The addition of alcohol and the redox reaction are repeated on the cation (42). The acetal ring of 43 is cleaved and the end product 44 obtained by hydrolysis ... 

Acrolein and condensable by-products, mainly acrylic acid plus some acetic acid and acetaldehyde, are separated from nitrogen and carbon oxides in a water absorber. However in most industrial plants the product is not isolated for sale, but instead the acrolein-rich effluent is transferred to a second-stage reactor for oxidation to acrylic acid. In fact the volume of acrylic acid production ca. 4.2 Mt/a worldwide) is an order of magnitude larger than that of commercial acrolein. The propylene oxidation has supplanted earlier acrylic acid processes based on other feedstocks, such as the Reppe synthesis from acetylene, the ketene process from acetic acid and formaldehyde, or the hydrolysis of acrylonitrile or of ethylene cyanohydrin (from ethylene oxide). In addition to the (preferred) stepwise process, via acrolein (Equation 30), a... 

Munoz-Hincapie, M., Morell, J. M., and Corredor, J. E. (2002). Increase of nitrous oxide flux to the atmosphere upon nitrogen addition to red mangrove sediments. Mar. Poll. Bull. 44, 992-996. 

The inhibited decomposition was studied again by Forst and Rice using ethylene, propene and nitric oxide. The addition of any of these scavengers was found to reduce the rate of decomposition as monitored by nitrogen evolution and also the ratio of CH4/N2 in the product, but each inhibitor affected both quantities to a different extent. Nitric oxide appears to be the most efficient inhibitor. As is the usual case, nitre oxide functions not only as an inhibitor but at higher pressures as an accelerator as well. The fully NO inhibited reaction was thought to correspond to the initial homogeneous unimolecular decomposition reaction... 

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