Solvent tests

We needed a solvent to separate sodium borohydride from sodium methoxide, concurrently produced in the synthesis. This led to a search for solvents for sodium borohydride. Among the solvents tested was acetone. A vigorous reaction ensued upon addition of the sodium borohydride, the active hydride disappeared, and analysis revealed the presence of 4 moles of isopropyl alcohol per mole of sodium borohydride introduced. 

Various extraction methods for phenolic compounds in plant material have been published (Ayres and Loike, 1990 Arts and Hollman, 1998 Andreasen et ah, 2000 Fernandez et al., 2000). In this case phenolic compounds were an important part of the plant material and all the published methods were optimised to remove those analytes from the matrix. Our interest was to find the solvents to modily the taste, but not to extract the phenolic compounds of interest. In each test the technical treatment of the sample was similar. Extraction was carried out at room temperature (approximately 23 °C) for 30 minutes in a horizontal shaker with 200 rpm. Samples were weighed into extraction vials and solvent was added. The vials were closed with caps to minimise the evaporation of the extraction solvent. After 30 minutes the samples were filtered to separate the solvent from the solid. Filter papers were placed on aluminium foil and, after the solvent evaporahon, were removed. Extracted samples were dried at 100°C for 30 minutes to evaporate all the solvent traces. The solvents tested were chloroform, ethanol, diethylether, butanol, ethylacetate, heptane, n-hexane and cyclohexane and they were tested with different solvent/solid ratios. Methanol (MeOH) and acetonitrile (ACN) were not considered because of the high solubility of catechins and lignans to MeOH and ACN. The extracted phloem samples were tasted in the same way as the heated ones. Detailed results from each extraction experiment are presented in Table 14.2. 

We report here studies on a polymer fi1m which is formed by the thermal polymerization of a monomeric complex tris(5,5 -bis[(3-acrylvl-l-propoxy)carbonyll-2,2 -bipyridine)ruthenium(11) as its tosylate salt,I (4). Polymer films formed from I (poly-I) are insoluble in all solvents tested and possess extremely good chemical and electrochemical stability. Depending on the formal oxidation state of the ruthenium sites in poly-I the material can either act as a redox conductor or as an electronic (ohmic) conductor having a specific conductivity which is semiconductorlike in magnitude. 

Topical application of a single 2 mL dose of undiluted -hexane had no effect on survival or body weight in exposed guinea pigs observed for 35 days after exposure (Wahlberg and Boman 1979). Deaths and/or effects on body weight were seen with similar doses of other common industrial solvents tested in this study (carbon tetrachloride, dimethylformamide, ethylene glycol monobutylether, 1,1,1-trichloroethane, and trichlorethylene). 

Dermal Effects. w-Hexane was 1 of 11 solvents tested for dermal toxicity in a male volunteer (Wahlberg 1984). Analytical grade -hcxanc (1.5 mL test area, 3.1 cm2) within a glass ring was applied to the volar forearm of the volunteer and left on the skin for 5 minutes. Blood flow values (expressed as a relative, dimensionless value) after dermal application of 1.5 mL of neat -hexane appeared to increase... 

Dermal Effects. Dermal effects have been observed in humans following exposure to -hexane. /7-Hcxanc was 1 of 11 solvents tested for dermal toxicity in a male volunteer (Wahlberg 1984). A slight transient erythema was observed after 10-20 minutes exposure to 1.5 mL -hexane and a stinging and/or burning sensation reported by the volunteer. Application of 0.1 mL neat -hexane did not cause clinical signs or affect blood flow. 

From what we see on the next page (properties) we can tell that codeine is not very soluble, so it stands to reason that this will be the last substance that will be eluted from the column. Acetaminophen looks the most soluble, so lets get rid of it first. Acetone looks like a good choice, but its hard to tell because the Merck Index did not say if the other substances are soluble or insoluble in acetone. Try a little and see what types of crystals appear upon evaporating off the solvent, test the melting point and see if it is exactly as stated for acetaminophen. If there are only two types of crystals then it may be easier to go ahead and elute these and then separate... 

In agreement with our aforementioned prediction, 98 and 99, both of which comprehend a secondary C2 axis, functioned as effective hosts for benzene, p-xylene, and 1,2,4-trimethylbenzene. " " On the contrary, the other benzo-fused derivatives of tetraphenylene, which are deprived of a secondary C2 axis, did not manifest any inelusion capacity in all solvents tested. ... 

Among the various polar solvents tested, acetonitrile, dichloromethane, and THF afforded good yields of the expected product, although with moderate diastereo-selectivity (Table 16, entries 1-3). The most suitable solvent was found to be diethyl ether. 5-[Hydroxy(phenyl)methyl furan-2(5//)-one 28a was obtained with the best yield and diastereoselectivity (Table 16, entry 4). With further optimization of the reaction conditions, we found that a lower catalyst loading (0.5 mol%) did not allow the reaction to proceed (Table 16, compare entries 5 and 4), although a higher catalyst loading (5 mol%) afforded the product with close diastereoselectivity but decreased yield (Table 16, compare entries 6 and 4). 

Expression of the catalytic capacity of the immobilized laccase was also observed in more than a dozen different solvents, provided that they were either saturated with water or, in the case of solvents miscible with water, small amounts of water had been added (Table III). No enzymatic reaction was observed when the solvents tested were free of water. No correlation was found between the activity of the immobilized laccase and the hydrophobicity of the solvent in which the reaction took place. The rate of laccase reaction in ethylacetate was only twice that in toluene, despite the fact that water-saturated ethylacetate contains 50 times more water than... 

Solvent test - A small amount of powder is poured onto the surface of a liquid and its sinking or floating behavior is observed. Liquids of different polarities such as toluene, formamide, ethylene glycol, and water were used. 

Films of the polyisoimides were cast from DMAC at 55 °C under reduced pressure (0.1 mm). A study of the isomerization reaction was conducted by FTIR and showed that the isomerization began at approximately 100 °C and was complete after 3 h at 250 °C. In all cases the thermally treated films were insoluble in all solvents tested. Composite films were produced with XVII and three commercial matrix systems a polyarylsulfone (Radel), a polysulfone (Udel), and an acetylene terminated isoimide thermosetting resin (IP-600). Films of the matrix and XVII were cast from DMAC. Slightly cloudy films, indicating some phase separation, resulted with both the Radel and Udel systems. Composite films cast with IP-600, however, were completely clear and showed no signs of phase separation. The structural similarity of the IP-600 resin and XVII may account for the greater homogeneity of the system. Property assessment of these films before and after thermal treatment is currently underway. 

Resolution of 3-aminopyrrolidine is reported in the hterature using diben-zoyltartaric acid via a 2 1 salt. We found that the (R)-enantiomer of the IN-Boc protected racemate could be crystallized in 32% yield and 99.5% ee from ethanol in a single crystallization with 0.25 mol equivalents of (R,R)-dibenzoyltartaric acid (Scheme 13.9). Other solvents tested gave poorer results. 

Although solvents have significant effects on the stabilities of macrocydic ligand complexes, the selectivity of the ligand to metal ions is not much influenced by solvents. For example, in Table 2.9, both ligands are most selective to K+ in all the solvents tested. 

Polyimides based on l-amino-3-phenoxy-5-(4-aminophenoxy)-benzene and snch dianhydrides as dianhydride of diphenyloxide-3,3 4,4 -tetracarboxylic acid, dianhydride A and dianhydride 6F are soluble in NMP, dimethylformamide (DMF), w-cresol, THF and chloroform. The polyimide based on benzophenone-3,3, 4,4 -tetracarboxylic acid dianhydride is partially soluble in w-cresol and NMP it is insoluble in chloroform, THF and DMF. Polypyromellitimide is insoluble in all the solvents tested. 

DMF is a good swelling solvent, the reaction does not proceed to completion due to the poor solubility of the reagents in that medium. The reagents have better solubility in DMSO, but use of 2 1 DMF-DMSO did not improve the reaction yield. Pyridine, which is a better solvent for the reagent and a good swelling solvent for polystyrene resin, was ultimately shown to be the best solvent tested. 

Figure 5. A replot of Figure 4 on a Log-Log scale clearly suggesting a systemmatic grouping of the polymer films with respect to their responses as a function of vapor pressure for the solvents tested. 

Addition of nucleophiles to electrophilic glycine templates has served as an excellent means of synthesis of a-amino acid derivatives [2c, 4—6]. In particular, imines derived from a-ethyl glyoxylate are excellent electrophiles for stereoselective construction of optically active molecules [32], This research and retrosyn-thetic analysis led us to believe that amine-catalyzed asymmetric Mannich-type additions of unmodified ketones to glyoxylate derived imines would be an attractive route for synthesis of y-keto-ce-amino acid derivatives [33], Initially, L-proline-catalyzed direct asymmetric Mannich reaction with acetone and N-PMP-protected a-ethyl glyoxylate was examined in different solvents. The Mannich-type reaction was effective in all solvents tested and the corresponding amino acid derivative was isolated in excellent yield and enantioselectivity (ee >95 %). Direct asymmetric Mannich-type additions with other ketones afford Mannich adducts in good yield and excellent regio-, diastereo- and enantioselectivity (Eq. 8). 

Polyacetylene appeared to be insoluble in all solvents tested [10,32]. Note, however, that units of polyacetylene in soluble form have been obtained by using graft or block copolymerisation methods, such as grafting polyacetylene to soluble polymers [33-37], grafting soluble polymeric chains on the main backbone of polyacetylene [38] and diblock copolymerisation [39-42]. In contrast to polyacetylene, polymers that can be obtained from substituted acetylenes are soluble in common solvents. 

While this is greater than was found in any other of the several solvents tested, it was established that the helicity was not a simple function of the solvent dielectric constant. 

Yoneda et a/.243 have investigated the reaction between alkyl halides and thiocyanate ion in a large number of solvents including NMA. While the rate of reaction in NMA was greater than in many of the solvents tested (e.g., formamide), the rate of product formation was still slower than in several solvents, particularly the NJM-dimethylamides and DMSO. Smiley244 has suggested that the reaction of dimethyl sulfate with thiocyanate ion in NMA proceeds by two different pathways. Dimethyl sulfate can react initially with the solvent to form an ionic intermediate which then reacts with the thiocyanate ion. Dimethyl sulfate also can react directly with the thiocyanate ion. 

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