Sulfuric acid-methanol

Fig. 38 Companson of manual dipping (A) with mechanized dipping (B) on the basis of scans and calibration curves [114] — 1 = cM-diethylstilbestrol, 2 = traw-diethylstilbestrol, 3 = ethinylestradiol Scanning curve 2 ng of each substance per chromatogram zone = 313 nm, /n > 390 nm Dipping solution water — sulfuric acid — methanol (85 + 15 + 1)...

Methyl esterification When prohexadione was treated with methanolic HCl (3%, w/v) or sulfuric acid-methanol (1 %, v/v) under reflux at 75 °C for 60 min, or with BFs-methanol (14%, w/v) under reflux at 75 °C for 30 min, the yield of the methyl ester of prohexadione was 95,93 and 82%, respectively (prohexadione, 10 qg, volume 2 mL of methanolic HCl, 2 mL of sulfuric acid-methanol and 1 mL of BFs-methanol). A solution of 1% (v/v) sulfuric acid in methanol was chosen for ease of preparation. Even if prohexadione was treated with 1% sulfuric acid in methanol at room temperature for 12h, the yield of prohexadione methyl ester was not different from that under reflux conditions as described in Section 6.3. The conditions for methyl esteriflcation in Section 6.3 were chosen because of shortening of the analysis time and the reproducibility of the reaction yield in residue analysis samples which could contain large quantities of contaminants. 

Alkylating reagents such as boron trifluoride-methanol, sulfuric acid-methanol, methanol-hydrochloric acid and methyl iodine-sodium hydride do not react efficiently with pyrithiobac. Trimethylsilyldiazomethane may be used for the methyl-ation of pyrithiobac. 

Sulfuric acid, methanol, and polystyrene are other industrially important chemicals that depend on equilibrium reactions for their production. Choose one of these chemicals, or another industrial chemical. Research methods that are used to produce it, as well as the products that are derived from it. To start your research, go to the web site above and click on Web Links. Prepare a report that outlines what you learned. 

This material melts at 78-79°. On t.l.c. [silica, development with w-hexane, visualization with sulfuric acid-methanol (1 1) and heating] the product had R, = 0.74. An impurity, R,--0.65, was present. 

The reactions of 1-TMS-cyclohexene oxide are similar (112). Treatment78,82 with sulfuric acid/water (in acetone), concentrated hydrobromic acid, sulfuric acid/ methanol, lithium aluminum hydride afford the corresponding compounds 1,2-di-hydroxy- (113)-, l-bromo-2-hydroxy- (114)-, l-methoxy-2-hydroxy- (115)-, 1-hydroxy-2-TMS-cyclohexane (117). Application of base to 115 yields 1-methoxy-l-cyclohexene (116). Pyrolysis of 112 gives a mixture of 1-trimethylsiloxy-l-cyclo-hexene (118) and 3-trimethylsiloxy-1-cyclohexene (ii9)77 (Scheme 13). 

Concentrated sulfuric acid, methanol, ethanol, 1-pentanol, 2-pentanol, acetic acid, isovaleric acid (3-methylbutanoic acid), benzoic acid, salicylic acid, anthranilic acid. 

On the other hand, free fatty acids can be methylated by acid-catalyzed procedures provided that the reaction time is kept short. For example, mild boron trifluo-ride-methanol or sulfuric acid (l%)-methanol reagents can be employed provided that scrupulous attention is paid to detail (2) in particular, freshly prepared reagent and the minimum reaction time are essential. For example, free fatty acids are fully methylated with boron trifluoride-methanol in 10 min at ambient temperature [or with sulfuric acid-methanol (1%) at 50°C for up to 1 h]. A phase-transfer catalyzed method employs basic conditions and can be used on a small scale, although the reaction does not always go to completion (2). However, trimethylsilyl-diazomethane, which is often recommended for free acids, can produce artifacts (8). 

Sulfuric acid + ferric sulfate Sulfuric acid + methanol Sulfuric acid + nitric acid Sulfurous acid Water + starch + sulfur dioxide... 

A) octanesulfonic acid 5 mM, triethy-lamine 0.5%, acetic acid 2.4% and methanol 15% (B) acetonitrile 100 /o methanol/water/ acetic acid (31 68.5 0.5), containing 5mM sodium hexasulfonate Aqueous 0.3% triethylamine (TEA) pH 7.4 with sulfuric acid/methanol... 

The preferred process consists of mixing sulfuric acid, methanol, and the fluori-nated emulsifier liquid resulting in a strongly acidic mixture containing the methyl ester of the perfluorinated emulsifier acid, that is, methyl perfluorooctanoate (Me-PFOA). Distillation of Me-PFOA yields a ternary mixture containing Me-PFOA along with water and methanol. Condensation of the vapor results in two phases. The lower phase is more or less pure ester while the upper phase consists of water... 

Sulfuric acid-methanol Prepare a 50% solution of H2SO4 in methanol spray and heat plates for several minutes at 100°C Brown-black spots on a colorless background... 

Although most steroids have their own U V-absorbance suitable for detection, localization of the spots can be based on the appearance of dark spots at 254 nm UV-light if a fluorescence layer is used most applications involve methods based on chemical reactions. Many spray reagents for the visualization of steroid spots have been described. However, special attention is needed to stabilize the color produced or the fluorescence induced on the plate. Sulfuric acid-methanol (or ethanol) is the most widely used reagent. In addition, phosphoric acid or antimony (III) chloride can be used to detect steroids on the plate or to detect steroids after spot elution. 

Many types of thermochemical processes for H2 produetion exist. The sulfuric acid processes (hydrogen sulfide, iodine-sulfur, sulfuric acid-methanol) and the Br-Ca-Fe eycle are currently the leading candidates. In the sulfuric acid processes, the high-temperature, low-pressure endothermic (heatabsorbing) reaction is the thermal decomposition of sulfuric acid to produce oxygen ... 

Spray with cone, sulfuric acid-methanol (1 1), developed by heating at 105 C for several min... 

Spray with sulfuric acid-methanol (85 15) heat to develop color... 

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