Ethanol, first analysis

Another pathway for the aromatization of the cr -adducts was found in the reactions of 3-pyrrolidino-l,2,4-triazine 4-oxide 81 with amines. Thus the treatment of 1,2,4-triazine 4-oxide 81 with ammonia leads to 5-amino-1,2,4-triazine 4-oxides 54—products of the telesubstitution reaction. In this case the cr -adduct 82 formed by the addition of ammonia at position 5 of the heterocycle undergoes a [l,5]sigmatropic shift resulting in 3,4-dihydro-1,2,4-triazine 83, which loses a molecule of pyrrolidine to yield the product 54. This mechanism was supported by the isolation of the key intermediates for the first time in such reactions—the products of the sigmatropic shift in the open-chain tautomeric form of tiiazahexa-triene 84. The structure of the latter was established by NMR spectroscopy and X-ray analysis. In spite of its open-chain character, 84 can be easily aromatized by refluxing in ethanol to form the same product 54 (99TL6099). 

Lussier [71] has given an overview of Uniroyal Chemical s approach to the analysis of compounded elastomers (Scheme 2.2). Uncured compounds are first extracted with ethanol to remove oils for subsequent analysis, whereas cured compounds are best extracted with ETA (ethanol/toluene azeotrope). Uncured compounds are then dissolved in a low-boiling solvent (chloroform, toluene), and filler and CB are removed by filtration. When the compound is cured, extended treatment in o-dichlorobenzene (ODCB) (b.p. 180 °C) will usually suffice to dissolve enough polymer to allow its separation from filler and CB via hot filtration. Polymer identification was based on IR spectroscopy (key role), CB analysis followed ASTM D 297, filler analysis (after direct ashing at 550-600 °C in air) by means of IR, AAS and XRD. Antioxidant analysis proceeded by IR examination of the nonpolymer ethanol or ETA organic extracts. For unknown AO systems (preparative) TLC was used with IR, NMR or MS identification. Alternatively GC-MS was applied directly to the preparative TLC eluent. 

Concentration of an ethanolic solution of dimethylglyoxime, cobalt(n) chloride and benzotriazole results in deposition of crystalline complex 68. The product is stable at room temperature however, it slowly decomposes upon heating. Thermal analysis reveals that the compound releases first the chlorine atom and 50% of the benzotriazole content to form a new complex that is stable to 225 °C. Probably in this new form, the benzotriazole moiety coordinates two cobalt ions simultaneously. Further heating to 350 °C removes the benzotriazolyl moieties completely <2003JPY699>. The first step of decomposition can be summarized as follows ... 

X-Ray analysis of crystals of 2-methyl-5-phenyltriazolo[4,5-, triazole 38, obtained by diffusion from methane/ethanol (PI space group), indicates there are two molecules per asymmetric unit. The first is essentially planar, with a mean deviation (non-H-atoms) of 0.03A and a maximum absolute torsion angle, C(2)-C(l)-N(5 )-N(4 ), of 3.4°. The second molecule has a more pronounced twist with C(2A)-C(1A)-N(5 A)-N(4 A) being 9.6° <1993ZK133>. 

The material is normally utilized directly without further purification. If the solid is very gray, it may be recrystallized. For the recrystallization the salt is dissolved in hot 95% ethanol (approximately 350 ml. per 100 g. of salt) containing decolorizing carbon, filtered rapidly, and the clear supernatant liquid is allowed to cool in a freezer (—20°). In this way, white crystals, m.p. 106-107°, may be obtained with nearly quantitative recovery. The checkers obtained the purified material of m.p. 108-109° with 95% recovery and used this material for the next step. The purified material has the following spectral data ultraviolet (95% ethanol) nm. max (e) 236 shoulder (13,200), 262 (2200), 268 (2680), 275 (1010) infrared (Nujol) cm-1 3090 weak, 3060 weak (aromatic CH), 1580 weak (C=C) proton magnetic resonance (CDCla), first-order analysis, 6 in p.p.m. 7.5-8.2 (multiplet 10H, Ha), 4.3 (poorly resolved triplet 2H, Hb), 3.75 (triplet 2H, Hd), 2-2.5 (multiplet 2H, He) coupling constant J in Hz. Jbc — 8, Jcd = 6.5. 

The buffers are uniformly made up of lithium citrate solutions of various pH and salt concentrations. The composition of the buffers is absolutely essential for a reproducible analysis and the supply companies are expected to meet the highest criteria in this respect. Due to impurities in the chemicals, the water, and the mixing devices, different lot numbers of buffers may have slightly different properties. A few tricks have been added over the years to improve the quality of the analysis, including the addition of methylcellosolve (methoxy ethanol) to the first buffer, and antioxidants to preserve methionine from oxidation to methionine sulfoxide. 

The simplified analysis is valid only when conditions (1) and (2) are met. Otherwise, the line intensities deviate considerably from the binomial pattern, the line frequencies differ considerably from those of the first-order analysis, and the first-order analysis may even predict the wrong number of NMR lines. (Even for ethanol, which was discussed above as an A3M2X system, a good NMR spectrometer will show that there are small but significant deviations from a first-order spectrum.)... 

Extraction is an essential step when analyzing solid samples. In some cases homogenization with a solvent suffices, but in others the sample must first be coimninuted. Water, solutions of acetic acid or sodium chloride, or more complex saline solutions are used as solvents. Mixtures of water and methanol or water and ethanol are also employed. The choice of solvent depends on the degree of selectivity desired in the extraction and whether the extraction yield is intended for quantitative analysis. Optimization of the extraction procedure is required in all cases, to fit the nature of the sample to be analyzed and the range of molecular weights of the peptides to be separated. For example, water has been used as the extraction solvent for cheese (33) and legumes (34). Saline solutions have been utilized to extract peptides from meat (35-38) and flour (39,40). Benedito de Barber et al. (41) examined differences in the extractability of amino acids and short peptides in various solvents (1M acetic acid, 70% ethanol, and distilled water) they concluded that extraction with 1M acetic acid yielded the maximum amino acid and peptide contents. 

Protein-rich foods can also be specially treated. According to Saag (135), in order to extract colorants from fish, samples are boiled, filtered, washed, with an ammonia solution to displace proteins, and then washed through Sephadex LH-20 with water. The colored zones are collected for HPLC analysis. Dairy products (ice cream, cheese, yogurt) are first mixed with acetone or ethanol to precipitate the protein, which is ground up with sea sand and Celite, and the slurry is placed in a column from which dyes are eluted with a solution of ammoniacal methanol (135,162). 

The first work in this field was probably that of Piletsky et al. [84] that described a competitive FILA for the analysis of triazine using the fluorescent derivative 5-[(4,6-dichlorotriazin-2-yl)amino]fluorescein. The fluorescence of the supernatant after incubation was proportional to the triazine concentration and the assay was selective to triazine over atrazine and simazine. The same fluorescent triazine derivative was applied to competitive assays using atrazine-imprinted films [70]. To this end an oxidative polymerization was performed in the presence of the template, the monomer(s) 3-thiopheneboronic acid (TBA) or mixtures of 3-amino-phenylboronic acid (APBA) and TBA (10 1) in ethanol-water (1 1 v/v) where the template is more soluble. The polymers were grafted onto the surface of polystyrene microplates. The poly-TBA polymers yielded a detection limit of 8 pM atrazine whereas for the poly-TBA-APBA plates it was lowered to 0.7 pM after 5 h of incubation. However, a 10-20% decrease in the polymer affinity was observed after 2 months. 

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