Pyridine solubles temperature, reaction severity

TABLE III. RELATIONSHIP BETWEEN REACTION TIME, TEMPERATURE, REACTION SEVERITY AND CONVERSION OF WYODAK COAL TO PYRIDINE SOLUBLES... 

Figure 1 shows the relationship between conversion, defined as gas + pyridine soluble liquids, and Rs derived at two different maximum temperatures. It can be seen that the conversions obtained at similar severities are the same (within experimental error). This is true even though all of these data involved rather extreme time-temperature fluctuations. Within limits a certain reaction severity can be obtained either at lower temperature (800°F) for longer time (6 min.) or at higher temperature for shorter time. 

A modification of the Pinner reaction using liquid HF has been used to improve the yields of the dithioester products. The N-protected amino acid and peptide nitriles 6 dissolve in liquid HF at temperatures below 0°C and react with thiols to form the imidothioic acid ester hydrofluorides 7 that further react with H2S in pyridine at 0°C to form the dithioesters 8 (Scheme 2)J71 Several isotopic dithioesters have been synthesized by this method with improved yield (Table 2). The use of liquid HF at low temperature helps to dissolve the amino acid nitriles that are not very soluble under Pinner conditions (HCl-saturated CH2C12). 

Silylation the final CH2C12 solution of the thioacidolysis sample is again carefully dried over Na2S04, 5-10/d of this dried organic solution is trimethylsilylated (TMS) at room temperature with 50/i of N,0 bis (trimethylsilyl) trifluoroacetamide (BSTFA) and 5 1 of GC-grade pyridine in a 200-/d reaction vial fitted with a Teflon-lined screwcap For soluble lignin samples, the silylation is complete within a few minutes, for lignocellulose residues, silylation is complete within 2 to 4h In both cases and with well-dried samples, silylations performed in the aforementioned vials are stable for several days (at least 48 h)... 

Grafting of BLG-NCA to aminopropylcellulose [1] could be accomplished at room temperature in the dried THF (Scheme 7). The cellulose derivative did not appear swollen in THF but there were enough active amino sites accessible on the surface to allow the reaction to proceed without difficulty. The graft copolymers were not soluble in most solvents, but did swell in THF, DMSO, and pyridine. Infrared spectra were very useful in confirming the extent of grafting and for identifying the secondary structure of the peptide units grafted. Several publications document the... 

The reaction of 2,5-dimethylpyridine with terephthalaldehyde [Eq. (1-7)] yielded a crystalline polymer that softened at 210°C and possessed a specific viscosity of 0.21 (H2SO4). The structure [13] of this polymer was in agreement with chemical and spectroscopic evidence 44). It had aldehydic termination its molecular weight determined by elemental analysis of its thiosemicar-bazone was 5000. This polymer is soluble in several solvents sulfuric and hydrochloric acids, benzyl alcohol, pyridine, quinoline, and m-cresol. When the polycondensation was performed at higher temperature (210°-220°C), an insoluble polymer was obtained. Whether the insolubility was due to a higher molecular weight polymer was not determined. 

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