Chloroform as a solvent

Gore et al.426 have used chloroform as a solvent for acetylation catalysed by aluminium chloride and at 45-55 °C find that a 2-methoxy substituent in naphthalene increases the reactivity of the 1 position 1.72 times, of the 6 position 3.8 times, and of the 8 position, 0.9 times the former and latter of these results indicate a considerable steric effect. Likewise, a 2-bromo substituent caused the reactivity of the 6 and 8 positions to be 0.63 and 0.58 times that of the corresponding positions in the unsubstituted compound. At 20-25 °C the relative reactivities of some polycyclics were as follows427 1-naphthyl, 1.0 3-phenanthryl 0.64 9-phenanthryl, 0.02 1-phenanthryl, 0.29 2-naphthyl, 0.28 2-phenanthryl, 0.12 4-phenanthryl, 0.0085. Some of these results seem to be due to steric hindrance, and the large difference in reactivity of naphthalene and biphenyl seems erroneous. 

Epoxidized oils were also used to modify PLA Ali et ah (2009) reported that its use as a plasticizer to improve flexibility. Thermal and scanning electron microscope analysis revealed that epoxidized soybean oil is partially miscible with PLA. Rheological and mechanical properties of PLA/epoxidized soybean oil blends were studied by Xu and Qu (2009) Epoxidized soybean oil exhibited a positive effect on both the elongation at break and melt rheology. Al-Mulla et al. (2010b) also reported that plasticization of PLA (epoxidized palm oil) was carried out via solution casting process using chloroform as a solvent. The results indicated that improved flexibility could be achieved by incorporation of epoxidized palm oil. 

If one of the species is anionic and we need to transport it to the organic phase, then a phase-transfer catalyst may be employed. Consider the example of benzyl penicillin where the reaction between phenyl acetic acid and the penicillin carboxylate ion, with penicillin amidase as a catalyst, is relevant, and which at pH 4.5 - 5.0 is shifted in the desired direction. Here a catalyst like tetrabutylammonium halide works, and with chloroform as a solvent 60% yield can be realized in contrast to a yield of only 5 - 10 % in water. 

Amic acids (AA) were prepared by two different methods. Stirring appropriate mixtures of amine and anhydride overnight in NMP yielded solutions of the desired amic acid suitable for F-NMR studies, hi order to discern a crude isomer composition, -C-NMR was performed on compounds prepared by a literature procedure utilizing chloroform as a solvent." This technique gave very high yields of very high-purity monoamic acid as the materials precipitated from the reaction mixture. 

Ferric chloride test Add 10 drops of 3% aqueous FeCl3 solution to 1 ml of a 5% aqueous (ethanol) solution of the compound in question. Phenols give red, blue, purple, or green colorations. The same test can be done by using chloroform as a solvent (detection limit, 50 pg). 

Trans-acetalisations are often performed in DMF at elevated temperatures under reduced pressure or a stream of nitrogen. These conditions result in removal of the methanol that is formed in the reaction and, as a. result, the benzylidenation is driven to completion. It has been reported that the use of chloroform as a solvent gives higher yields and, in this case, pyridinium p-toluene sulfonate (PPTS) may be used as a catalyst. 

In 1970, Warren et al. addressed the determination of trace amounts of water in mono-, di-. and triglycerides by NIR spectrometery [7]. Using chloroform as a solvent, the investigators studied the combination band of water occurring at 1896 nm in the presence of the -OH groups on glycerides to determine water down to 0.05%. 

Dibenzylamine substitution and alcoholysis compete in reactions of PhP(X)Cl2, where X = O or S, in stabilized chloroform as a solvent.344 The oxy-compound gives both PhPO[N(CH2Ph)2]2OEt and PhPO(OEt)2, but when the stabilizer is removed the products are PhPOCl[N(CH2Ph)2] and the anhydride (44). Reactions of the thio-derivative are similar, but two... 

However, the use of chloroform as a solvent has certain disadvantages, in particular a concentration dependence of spectra in this solvent has been noted 172>. Furthermore, many porphyrins, including porphine itself, are only sparingly soluble in chloroform, and this has lead to wide use of trifluoroacetic acid (TFA) as a solvent, in which these compounds exist as di-cations. Protonation of two of the nitrogen atoms results in an increased separation between the chemical shifts of the internal and external protons. Thus, in deuterio-TFA the tneso protons of the octaethylporphine, 41, are shifted even further downfield to t —0.98, while the imino protons, whose increased shielding more than compensates for the positive charge on the nitrogen atoms, are shifted upheld to t 14.65 m.i72). 

The published procedure [142] uses chloroform as a solvent for the bromination. We used a small amount of dichloromethane, which can be easily removed by evaporation in vacuo. The authors heat the reaction mixture with alcoholic potassium hydroxide without having removed the solvent chloroform this reacts... 

Pyrylium Salts.—Acetylation of isoparaffins, such as (68), under Friedel-Crafts conditions at low temperatures produces pyrylium salts (69). The ratio of reactants and the presence or absence of chloroform as a solvent affect the yield of the mixture of isomers which is often obtained, through the intermediacy of a carbenium ion. The pyrylium salts were converted into pyridines (70) by aqueous ammonia. However, 3-methylpentane gave only 3-ethyl-2,4,6-trimethyl-pyridine. 

Cram and co-workers studied thermodynamic and structural aspects of the interaction in depth. /-Butylamine was typically used as a standard guest, the association of which with a huge variety of crown ethers having different ring sizes, numbers and positions of oxygen atoms, and different substituents was measured in chloroform as a solvent. Picrate, thiocyanate, or hexafluorophosphate extraction was a common tool (for the later discussion of the role of the counterion in complexation see Ref. 47 as concerns pH dependence, it is determined typically by the ranges of existence of the ammonium ion in the protonated and the host in the neutral forms). Some illustrative examples of K ss for t-butylamine thiocyanate, extracted into chloroform at 24 C [9], are listed below ... 

Caffeine has the molecular formula CSH10N4O2 and is present in tea, coffee and cola. It can be extracted from tea or coffee by Soxhlet extraction, using trichloromethane (chloroform) as a solvent. A disadvantage of Soxhlet extraction is that it takes time, often many hours. Supeivritioal fluid extraction (SFE) is a recently developed technique that can shorten extraction times considerably. The solvent used is a supercriticai fluid, a substance that is above its critical temperature and pressure (see page 168). Carbon dioxide, for example, becomes... 

Dinitrogen pentoxide (N2O5) decomposes in chloroform as a solvent to yield NO2 and O2. The decomposition is first order with a rate constant at 45 °C of 1.0 X 10 s. Calculate the partial pressure of O2 produced from 1.00 L of 0.600 M N2O5 solution at 45 °C over a period of 20.0 hr if the gas is collected in a 10.0-L container. (Assume that the products do not dissolve in chloroform.)... 

Schauer et al. (2003) used poly(2,6-dimethyl-l,4-phenylene oxide) (PPO) membranes to separate water-EtOH mixtures by PV. Asymmetric membranes were prepared from solutions containing chloroform as a solvent and 1-butanol as a nonsolvent via the phase inversion technique. Dense membranes were prepared from chloroform solution by evaporation. Nonporous membranes (membranes precipitated from solutions with a small amount of the nonsolvent or prepared by evaporation) were preferentially permeable to water. Microporous membranes (prepared from solutions with a large amount of the nonsolvent) were preferentially permeable to EtOH, provided the membrane was not wetted by the feed solution. 

Fig. 6.8. Intrinsic viscosity [q] as a function of the molar mass for poly(glutamic acid benzyl ester) (PGE) in two different solvents at 25 X (data from [62]).The slope of 1.7 for the [q]-M-re a-tionship for chloroform as a solvent indicates a rod-like (helical) structure, whereas in dichloro-acetic acid a slope of 0.87 indicates a flexible coil for the solution structure...

Polyethylene monofilaments (48 tex) were coated with a conductive polymer composite based on dispersion of Printex L6 carbon black particles in Evoprene 007 solution, using chloroform as a solvent (Cochrane et al., 2007). Two-ply polyethylene filaments were coated with the polymer solution as described above. The two ends of the coated polyethylene filaments were additionally coated with silver paint in order to reduce contact resistance, and fine copper wire was attached to the two ends with the help of this paint. In this way, secure connections were realized. Sensor strucmral and geometrical parameters along with initial electrical resistance are shown in Table 14.1. 

Chloroform. Chloroform is similar to carbon tetrachloride in its toxicity. It has been used as an anesthetic. However, chloroform is currently on the list of suspected carcinogens. Because of this, do not use chloroform routinely as a solvent in the laboratory. If it is occasionally necessary to use chloroform as a solvent for special samples, then you must use it in a hood. Methylene chloride is usually found to be a safer substitute in procedures that specify chloroform as a solvent. Deuterochlo-roform, CDCI3, is a common solvent for NMR spectroscopy. Caution dictates that you should treat it with the same respect as chloroform. 

The extraction of santonine from Flores Cinae can be carried out using chloroform as a solvent at laboratory temperatures. The extract is filtered, chloroform distilled off, the residue dissolved in ethanol and polarographed after diluting with a twofold volume of an aqueous solution of 0-2 N lithium sulphate. 

We report on the use of Preyssler s anion and HPA catalysts for obtaining substituted flavones and chromones for the cyclization of l-(2-hydroxyphenyl)-3-ar-yl-l,3-propanediones. The reactions were performed using chloroform as a solvent at reflux temperature conditions and in the absence of solvent, at 110°C. We had excellent yields and high selectivity at these conditions. The presented synthetic method is a simple, clean, and environmentally friendly alternative for synthesizing substituted flavones and chromones (Scheme 3.19) [59]. 

FIGURE 3.2 Dependence of the intrinsic viscosity [r ] (1) and the average molecular weight (2) of the formyl derivative of the syndiotactic 1,2-PB from the functionalization degree of the a polymer (with chloroform as a solvent 25°C). 

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