Toluene carrier method

The research activities of Professor Michael Szwarc started in 1945, after the second World War, when he joined the research group of Professor Polanyi in Manchester, England. There he developed a pyrolytic technique (toluene carrier method) that allowed him to determine bond dissociation energies of over fifty polyatomic molecules. The work done until 1950 was summarized in a review article published in Chem. Rev. 47,75,1950 and earned him a D.Sc. in 1949. 

The value of D C - Br) in methyl bromide has been determined by the pyrolysis method by Szwarc to be 67 kcal. The strength of the C - Br bond is such that it is particularly suited to pyrolyses using the toluene carrier gas technique, and Szwarc and his collaborators have exploited this property very thoroughly. It is convenient to list here the forty-odd values of D(G - Br) in various compounds obtained in this way. Ladacki and Szwarc 28 5 give the following values for the activation energy, frequency factor and rate constant of the pyrolysis. The constancy of the frequency factor over a... 

The principal experimental methods for measuring bond dissociation energies in polyatomic molecules have been described in detail by Cottrell (35). Two methods in particular have proved fruitful in recent years, namely the toluene carrier gas technique introduced by Szwarc (167) to investigate the unimolecular kinetics of pyrolytic decomposition reactions, and the electron impact method, as applied by Stevenson (165) and widely used since by several investigators. These methods do not usually give very sharp D values, and the number of well-authenticated ( 2... 

Nimodipine in plasma was determined by a GC method [17]. Plasma was treated with 2 M NaOH after addition of the internal standard, and then extracted with toluene. The column (10 m x 0.31 mm) consisted of cross-linked 5% phenylmethyl silicone, and the method used temperature programming from 90°C (held for 1 min) to 255°C at a heating rate of 25°C/min. Helium was used as a carrier gas, and the N-P detection mode was employed. The calibration graph was linear from 2 to 50 ng/mL, and the detection limit was 0.5 ng/mL. 

The first application of the method was in the thermal decomposition of toluene itself, which can be regarded both as carrier gas and as reactant if the fraction of decomposition is very small, and Szwarc restricted this to O-Ol-l per cent in his experiments... 

Figure 3. Comparison of packed and Megabore columns, EPA Method 602. FID, and identical injections in both cases. Top, 6 ft x 1/8 in stainless steel column packed with 5% AT-1200 + 1.75% Bentone 34 on 100/120 Chromosorb WAW 50°C (4 min), 8°/min to 100°C 20 min hold. Helium carrier at 50 mL/min. Bottom, 30 m x 530 urn Megabore column, coated with a 1 um film of DB-Wax 45°C (2 min), 8°/min to 100°C. Helium carrier at 30 mL/min. Solutes 1) benzene 2) toluene 3) ethylbenzene 4) chlorobenzene 5) 1,3-dichlorobenzene 6) 1,4-dichlorobenzene 7) 1,2-...

The iron vapor-toluene reaction has evoked interest because of the lability of the proposed bis(arene)iron complex to ligand subsitu-tion and to loss of both toluene molecules to free the metal atom. In the latter case the toluene molecules may be usefully regarded as metal atom carriers which can be used to direct the latent reactivity of the atom in subsequent solution phase chemistry. In this way the metal atom experiment can benefit from the convenience and additional versatility afforded by bench-top chemical manipulations. These results are relevant to a reported preparation of a dehydroxy-lated silica-supported Fischer-Tropsch catalyst from a static reactor codeposition of Fe and toluene.(46) In the liquid phase, iron atoms "bottled" in this way have also been utilized in an exceedingly mild method for making minute catalytically active superparamagnetic clusters on the surface and within the cavities of a dehydrated sodium zeolite Y.(38) Using the rotary reactor, preformed solutions of solvated iron atoms (as the toluene complex) are cannulated below their decomposition temperature out of the flask to a cold slurry of the support in toluene. Diffusion of intact... 

The analysis of the collected average shift samples was made with a method validated by us, based on NIOSH method 1600/1994 (National Institute for Occupational Safety and Health). After eluation of the activated charcoal with toluene the test was made with a gas chromatograph with mass selective detector Perkin Elmer and capillary column DB-5, 30 m long and thickness of the coating 0.25pm. Helium was used as carrier gas. Apparatus conditions injector temperature 250°C, detector temperature 250°C, carrier gas pressure - 7 psig. The quantitative assessment of the samples was performed after absolute calibration with standard solutions of carbon disulfide in toluene. The limit of detection of the method is 0.01 mg/m3 at 25dm3 air sample. 

Virtually all of the methods for determining acyl groups developed up to now are based on re-esterification of the initial compound with sulphuric acid, a mixture of methanol with hydrochloric or p-toluenesulphonic acid, or with a mixture of p-toluene-sulphonic acid and its methyl ester [165—170]. The esters formed in the reaction were determined by analysing an aliquot of the reaction solution or by blowing-off the reactor with a carrier gas. Alkaline hydrolysis with subsequent determination of acetic acid has also been used for identifying acyl groups [167]. 

The amine and the ketone are heated with azeotropic removal of the water formed, the carrier being benzene, toluene, xylene, or an excess of the ketone. Water-soluble amines and ketones, which cannot be treated in this way, are kept together at room temperature for 24 h after addition of concentrated hydrochloric acid (3 g per 5 moles of amine and ketone), after which the water produced is removed by solid sodium hydroxide and the organic phase is distilled. Very good yields of about 40 aliphatic ketimines were obtained by these two methods.886... 

Various alternative precursor delivery processes have been designed specifically to circumvent the low volatility and low thermal stability problems associated with (Ba(dpm)2 (see Sect. 2.4.1.2). The first method involves the dissolution of Y(dpm)j, Ba(dpm)2 and Cu(dpm)2 precursors in solvents such as butylacetate [188], THF [153, 156], toluene [189], decane [190] and supercritical carbon dioxide [191]. According to this process, termed aerosol-assisted CVD (AACVD), the multicomponent precursor solution is atomized or vaporized into a carrier gas stream or directly into the reaction chamber, with deposition occurring on a heated substrate. Some attractive features of AACVD include deposition at atmospheric pressure, the ability to use thermally sensitive precursors, and a high precursor transport rate [189]. Figure 2-30 shows a sum-... 

Samples in methanol were analyzed by HPLC, and samples in toluene or hexane were analyzed by GC. The HPLC method used a Cl8 column (Shimadzu Premier C18, 5 p) with acetonitrile-water mixture as mobile phase with gradient from 70 to 100% acetonitrile and UV detection at 280 nm. The GC method consisted of a 0.53 mmx 15 m DB5 column, with helium as the carrier gas, injector and detector temperatures of 250°C, and an oven temperature of 210°C. 

Second method about 400-500 mg of sample were treated with HCl and extracted into toluene and cysteine, and back-extracted into toluene. The extract was dried with anhydrous Na2S04. The separation was by capillary gas chromatography (column of 30 m length, internal diameter of 0.53 mm stationary phase S.P.B. 608 Supelchem, 0.50 pm film thickness injection of 1 pL temperature of the injector of 250 °C, temperature of the ECD detector of 350°C, column temperature of 90°C N2 as carrier gas at 10 mLmin Ar/ CH4 as make up gas type at 60 mLmin ). Calibration was by calibration graph with CH3HgCl in toluene C2H5HgCl was used as internal standard. 

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