Sulfuric acid, amino acetonitrile

Amino-2-methylpropane, Methylene chloride, 1,3,5-Trifluoro-2,4,6-trinitrobenzene, Potassium hydrogen carbonate, Trifluoroacetic acid, Cyanotrimethylsilane, Nitromethane, Acetonitrile, Sulfuric acid... 

Remove the guard column before washing the analytical column, so that impurities from the guard column are not washed into the analytical column. Bare silica and cyano- and diol-bonded phases are washed (in order) with heptane, chloroform, ethyl acetate, acetone, ethanol, and water. Then the order is reversed, using dried solvents, to reactivate the column. Use 10 empty column volumes of each solvent. Amino-bonded phases are washed in the same manner as silica, but a 0.5 M ammonia wash is used after water. C18 and other nonpolar phases are washed with water, acetonitrile, and chloroform, and then the order is reversed. If this is insufficient, wash with 0.5 M sulfuric acid, and then water. 

To a suspension of 7-amino-3-vinyl-3-cephem-4-carboxylic acid (11.25 g), 2-(aminothiazol-4-yl)-2-(tert-butoxycarbonylmethoxyimino)acetic acid S-mercaptobenzothiazole ester (23.88 g) in ethylacetate (266 ml) and water (9 ml) at 2°C is added triethylamine. After completion of the reaction, water is added and pH is adjusted to 2.1 with diluted sulfuric acid. The phases are separated and the aqueous phase is extracted with ethylacetate. The organic extracts are combined and concentrated to a volume of 120 ml, then acetonitrile (100 ml) and formic acid (22 ml) are added. The mixture is stirred at 30-35°C for 1 hour. The mixture is cooled to 2°C, the precipitate is filtered, washed with acetonitrile and dried to obtain 20.86 g of 5-thia-l-azabicyclo(4.2.0)oct-2-ene-2-carboxylic acid, 7-(((2Z)-(2-amino-4-thiazolyl)(carboxymethoxy)imino)acetylamino)-3-ethenyl-8-oxo-, (6R,7R)-(Cefixime). 

Procedure Place 10 mg (ca. 0.04 0.08 mmole) of sulfur-containing amino acid and 10 mg of phenanthrene (as internal standard) in a 16 X 76 mm culture tube (screw cap with Teflon liner). Add 0.5 ml (ca. 2.6 mmoles) of BSA (or 0.5 ml ca. 3 mmoles, of BSTFA) and 1.5 ml of acetonitrile. Screw the cap on the tube and immerse just to the top of the liquid level in an oil bath at 150° for 5 minutes. Allow to cool and inject 5 JU.1 into the gas chromatograph. The chromatograms shown in Figs. 22 and 23 illustrate the results obtained by this procedure. The authors claim that the minimum detectable limit at a 2 1 signal-to-noise ratio with respect to the flame ionization detector is about 5 ng of sulfur-containing amino acid injected on the column. 

When the arenediamines 2,4,6-trimethylbenzene-l,3-diamine and 2,2, 6,6 -tetramethyl-4,4 -methylenediphenylamine were treated under the same reaction conditions with 1.4 equivalents of B0C2O and 1.0 equivalent of DMAP per amino group in acetonitrile at room temperature Method A, work-up with sulfuric acid), 2,4,6-tnmethylbenzene-l,3-diisocyanate 339 and 2,2, 6,6 -tetramethyl-4,4 -meth-ylenediphenyl isocyanate 340 were obtained in yields of 84% and 93%, respectively. Arenediyl diisocyanates play a very important role as monomers for the industrial synthesis of polyurethanes and polyureas [226]. 

The following chiral reagents were employed for diastereomer formation before sample application and chromatography on silica gel or silica gel G TLC plates (L)-leucine Af-carboxyanhydride for D,L-dopa-carboxyl- " C separated with ethyl acetate/formic acid/water (60 5 35) mobile phase and detected by ninhydrin [7 f 0.38 (d)/0.56 (l)] [43] Af-trifluoroacetyl-L-prolyl chloride for D,L-amphetamine separated with chloroform/methanol (197 3) and detected by sulfuric acid/formaldehyde (10 1) (Rf 0.49 (d)/0.55 (l)) [44] Af-benzyloxycarbonyl-L-prolyl chloride for D,L-methamphetamine separated with n-hexane/ethyl acetate/acetonitrile/diisopropyl ether (2 2 2 1) and detected by sulfuric acid/formaldehyde (10 1) [/ f 0.57 (l)/0.61 (d)] [44] (l/ ,2/ )-(-)-l-(4-nitrophenyl)-2-amino-1,3-propanediol (levobase) and its enantiomer dextrobase for chiral carboxylic acids separated with chloroform/ethanol/acetic acid (9 1 0.5) and detected under UV (254 nm) light R[ values 0.63 and 0.53 for 5- and / -naproxen, respectively) [45] (5)-(4-)-a-methoxyphenylacetic acid for R,S-ethyl-4-(dimethylamino)-3-hydroxybutanoate (carnitine precursor) with diethyl ether mobile phase [/ f 0.55 R)/0J9 (5)] [46] and (5)-(4-)-benoxaprofen chloride with toluene/acetone (100 10, ammonia atmosphere) mobile phase and fluorescence visualization (Zeiss KM 3 densitometer 313 nm excitation, 365 nm emission) (respective R values of R- and 5-isomers of metoprolol, oxprenolol, and propranolol were 0.24/0.28, 0.32/0.38, and 0.32/0.39) [47]. 

An improved electrochemical synthesis of chiral oxazolidin-2-ones from 1,2-aminoalcohols was achieved by reaction with C02 and electrogenerated acetonitrile anion <02TL5863>. The reaction of A-protected amino acids with paraformaldehyde was greatly accelerated by microwave irradiation <02TL9461>. Oxazolidin-2-ones were synthesised by sulfur assisted thiocarbonylation of 2-aminoethanols with carbon monoxide and subsequent oxidative cyclisation with molecular oxygen <02T7805>. 

Terpenes Ammonia NII3) Hydrogen cyanide (HCN) Acetonitrile (CHcCN) Cyanogen (NCCN) Amines, heterocydes, amino acids Methyl chloride CH3CI) Sulfur compounds (lLS,COS, DMS,DMDS) Aerosols (4 wt % Soot) Nitrogen (N,) Cyanogen (NCCN) Sulfur dioxide (SO,) Aerosols (40 wt % Soot) ... 

We focused our attention on L-Cys (Scheme 19.2) because of its importance as a sulfur-containing semiessential amino acid, which can be biosynthesized in humans and yet, due to its relatively low content in food, it is also used as a food additive (denoted as E920). L-Cys is an important building block of proteins that are used throughout the body, and it can physiologically be transformed to glutathione (a powerful antioxidant [22]), or taurine (essential for cardiovascular function, development and function of skeletal muscles, the retina, and the central nervous system [23]). Thus, the main aim of this study [14] was to employ TLC-densitometry and TLC-ESI-MS in order to demonstrate an ability of L-Cys to spontaneously undergo chiral conversion and condensation, when dissolved in 70% aqueous acetonitrile. 

Hydrazine hydrate is known to react with acetonitrile in the presence of sulfur or ethanol to form 4-amino-3,5-dimethyl-l,2,4-triazole or 3,6-disubstitued-l,2-dihydro-l,2,4,5-tetrazines. The initial product, which is disubstituted l,2-dihydro-l,2,4,5-tetrazine, is readily oxidized to the pink colored 1,2,4,5-tetrazine it may also rearrange at elevated temperature or on treatment with an acid to the corresponding 1,2,4-triazole. The triazole compound is obtained by the reaction of hydrazine hydrate and acetonitrile in the presence of CO2. The presence of CO2 in the formation of the six-membered ring intermediate is essential, and has been confirmed by repeating the experiments in the absence of CO2. However, the exact role of CO2 in this reaction is not clear. Figure 6.1 gives a possible mechanism for the formation of the triazole from hydrazinium hydrazine carboxylate and acetonitrile. 

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