Methyl Toluene Research Articles

α‐substituierte Phosphonate. 47. PC‐Spaltungen bei geminalen Trisphosphorylverbindungen

α‐Substituted Phosphonates. 47. Splitting of PC‐Bonds from Trisphosphoryl CompoundsHexaethyldimethylaminomethyl‐trisphosphonate (2a) reacts with HCl or trimethylsilylbromid/water by splitting off one phosphoryl group, giving dimethylaminomethyl‐bisphosphonic acid (7). The result of methylation of 2a depends on the reagent: with methyliodide one phosphoryl group is split off, and the ammonium salt 11a is formed, while with methyl toluene sulfonate or dimethylsulfate the expected quarternary ammonium salts 10b or 10c are formed. One phosphoryl group of 10c is split off under acidic as well as alkalinous conditions: acidic hydrolysis gives the bisphosphonic acid 15, while under alkalinous conditions the known ylid 16 is formed.

Effect of high pressure on the kinetic isotope effect in the abstraction of hydrogen and deuterium atoms by the cumyloxy radical

The abstraction of a deuterium atom from the CD/sub 3/ group in deuterotoluenes is more accelerated by pressure than the abstraction of a hydrogen atom from the toluene methyl group, which is reflected in a decrease in the kinetic isotope effect k/sub H//k/sub D/ with increasing pressure. The value for k/sub H//k/sub D/ = ((DMPC)/(AP))H/((DMPC)/(AP))/sub D/ were determined by measurement of the amounts of dimethylphenylcarbinol (DMPC) and acetophenone (AP) formed upon the decomposition of 0.1 mole/liter dicumyl peroxide in C/sub 6/H/sub 5/CH/sub 3/, C/sub 6/H/sub 5/CD/sub 3/, and C/sub 6/D/sub 5/CD/sub 3/ at 399/sup 0/K.

Magnetization-transfer NMR determination of rates of exchange of solvent in and out of gel polymer beads

Rate constants for exchange of toluene in and out of swollen beads of a 10% crosslinked copolymer of styrene and chloromethylstyrene and for spin-lattice relaxation of the toluene methyl carbon atom inside and outside the beads have been determined by 13C NMR magnetization-transfer kinetics. Evaluation of complementary selective inversion, single selective inversion, and nonselective inversion data by Marquardt nonlinear least-squares analysis showed that only complementary selective inversion experiments were adequate for calculation of the exchange rate constants. A DANTE pulse sequence was used for the selective 180° pulse.

Precipitation studies of polystyrene from solution

AbstractThe precipitation behaviour of polystyrene from solution was studied for the ternary system of polymer/solvent/precipitant, the solvent being toluene or ethyl methyl ketone and the precipitant methanol. The relationships between the efficiency of precipitation and temperature of precipitation, concentration of the solution, molecular weight of the polymer, and the solvent system were investigated. The optimum volume ratio of the polymer solution to precipitant, in order to obtain maximum efficiency of precipitation for a particular system, was derived from graphical plots. The results indicated that the efficiency increases with increasing concentration of the solution, molecular weight of polymer, and thermodynamically “poorer” solvent, but decreases with increasing temperature between 200 K and 300 K. It was also observed that a plot of the efficiency of precipitation versus the volume ratio of polymer solution to precipitant passes through a maximum for all the systems studied. The optimum volume ratio of polymer solution to precipitant exhibits a similar behaviour just as in the case of the efficiency of precipitation. Information obtained from this study enables one to select the best combination of the parameters affecting precipitation, in order to produce a high yield of precipitate of polystyrene at a relatively low cost of solvent and precipitant for a particular temperature of precipitation.

The sign of the electron-releasing effect of the methyl group

In 1926 the late professor Sir Robert Robinson, O.M., F.R.S., noting that a group, which acts as a source of electrons, should, according to the conventions of physics , be termed negative, introduced the symbol —I to denote the electron-releasing inductive effect of a group (such as the methyl group CH 3 = Me in toluene) (1). In 1926 the late Professor Sir Christopher Ingold, F.R.S., reversed this sign convention from —I to +1 (2). This reversal has only once briefly been discussed, as far as my knowledge goes (3). The writer is probably the only living person who knows the reason for this sign reversal, because in 1926 he asked Ingold the question. Ingold’s answer was simple, mathematical , and logical: ‘The electron-releasing effect of the methyl group in toluene increases the electron density in the aromatic nucleus, and the differential coefficient of an increasing quantity is positive.’The symbols +1 for inductive electron-release and —1 for inductive electron-attraction introduced by Ingold have been generally accepted and are now used world-wide.

Infrared and Raman study of the fast internal motion of non-rigid molecules, method of selective deuteration

The internal rotation of the methyl group in toluene and nitromethane and the ring-puckering motion of cyclopentene have been studied by analysing the infrared and Raman spectra of the ν(CH) or ν(CD) stretching vibrations of the CH or CD oscillators isolated in selectively deuterated molecules. The interpretation of the spectra is supported by a general formalism of anharmonic coupling between the high-frequency and low-frequency modes. The latter is described in quantum mechanics in the gas and solid state but takes a stochastic character in the liquid state.

Kinetic isotope effect in trans-alkylation with ethylbenezene

Kinetic isotope effect (KIE) measurements in the trans-alkylation of toluene and benzene with ethylbenzene in hexane in the presence of AlBr3 at 313 K indicate that deuterium in the toluene methyl group causes a small inverse KIE characteristic for a π-complex transiton state. The small direct KIE found for the reaction with C2D5C6H5 does not agree with a mechanism involving alkyl-and α-phenylalkyl cations.

The analysis of the torsional structures of the CH3(D3) asymmetric stretching vibrations of gaseous toluene

The torsional structures of the asymmetric stretchings of the methyl group of toluene are analyzed on the basis of the C2v symmetry. The torsional structures observed in the IR spectrum of gaseous toluene-h3 are explained by use of the twofold and sixfold potentials in the first excited state of the CH3 asymmetric stretchings. The fundamentals analyzed are 2996.3 cm−1 for the B2 mode and 2981.8 cm−1 for the B1 mode. The Raman bands observed here at 2989 and 3012 cm−1 are assigned to the fundamentals of the A1 and A2 modes, respectively. The torsional structures of the CD3 asymmetric stretchings are explained satisfactorily by use of the potential constants obtained in the CH3 system.

Retention of organic solvent vapors in plastic bags. Part 5. A basic study about correction methods of concentration of organic solvent vapors in plastic bags (author's transl)

The concentration of organic solvents in plastic bags is decreased with time elapsed. It was supposed to permeate in plastic films. Therefore, we assumed that this phenomenon will be approximately regulated by the first order order reaction (C = C0e-kt). We got the permeation coefficient (k) by experiments and used it to correct organic solvent concentrations in the plastic bags. In the present experiment, we used Tedlar bags, toluene and ethyl methyl ketone (MEK) as organic solvents and determined the values by gas chromatography. Initial organic solvents concentration and that after t hr standing being taken as C0 and C. k Values are obtained by the formula C = C0e-kt. Mean values of k about toluene and MEK were found: k = 6.00 X 10(-3) and k = 4.86 X 10(-3). The results by this correction were as follows: Retention of toluene concentration in 24 hr standing bags showed to increase from 81% to 93%, or, in the case of 96 hr standing bags, it was shown to increase from 56% to 100%. Retention of MEK concentration in 24 hr standing bags showed to increase from 86% to 97%, or, in the case of 96 hr standing bags, it was shown to increase from 68% to 109%.

Selective deuteration and the anomalous temperature dependence of proton spin–lattice relaxation in polycrystalline p-t e r t-butyltoluene

Proton spin–lattice relaxation times T1 are reported for p-t-butyltoluene (I); the derivatives having the toluene methyl group relaced with CH2D (II), CHD2 (III), and CD3, (IV); and the derivative having all of the ring positions deuterated (V). The measurements were made on polycrystalline samples in the temperature range 4–260 K at both 17.1 and 36 MHz. Raman spectra are also reported for these compounds at 77 K. All of the compounds show T1 minima between 100 and 200 K which are associated with motions of the protons in the t-butyl group and, except for compound V, with protons attached to the ring. Compounds I, II, and V exhibit two T1 minima below 10 K which are presumably associated with motions of the protons in the toluene methyl group. The Raman peaks do not permit the form of the potential function for internal rotation of this methyl group to be established. It is argued that a potential having both three and sixfold contributions is consistent with the low temperature T1 data. For compound II, which contains CH2D, the 17.1 MHz experiment gives frequency dependent T1 minima at 13.5 and 52.6 K which show apparent activation energies of 80±20 and 640±10 cal/mol, respectively. If these energies are associated with the torsional splitting E1−E0 and the activation energy Vmax−E0, respectively, the required ratio of V6 to V3 contributions in the potential function is 0.71.

Thermolysis of Bis(diarylmethylenecarbamoyl) Peroxides

Abstract Diacyl peroxides of structure (XC6H4)2C=N–C(=O)OOC(=O)–R (R=(XC6H4)2C=N, X=H (1), X=2-CH3 (3), X=4-CH3; R=4-ClC6H4, X=H (2) have been prepared by the reaction between the corresponding carbamoyl chloride and hydrogen peroxide-urea complex in the presence of pyridine or between the carbamoyl chloride and 4-chloroperbenzoate in anhydrous ether at low temperature. Thermolysis of 1–3 follows first order kinetics. The large rates of thermolysis of 1 and 3 relative to those of bis(diphenylmethyleneacetyl) peroxide have been ascribed to steric compressions of 1 and 3 in the ground state and to the concerted cleavage of three bonds. Stable diphenylmethyleneamino radicals do not substitute in toluene by themselves but they do with the aid of aroyloxy radicals. The iminyl radicals abstract hydrogen from the methyl group of toluene, and the rate constant has been estimated to be 5×102–2×103M−1s−1 at 50 °C.

Electrophilic and free radical nitration of benzene and toluene with various nitrating agents

Electrophilic nitration of toluene and benzene was studied under various conditions with several nitrating systems. It was found that high orthopara regioselectivity is prevalent in all reactions and is independent of the reactivity of the nitrating agent. The methyl group of toluene is predominantly ortho-para directing under all reaction conditions. Steric factors are considered to be important but not the sole reason for the variation in the ortho/para ratio. The results reinforce our earlier views that, in electrophilic aromatic nitrations with reactive nitrating agents, substrate and positional selectivities are determined in two separate steps. The first step involves a pi-aromatic-NO(2) (+) ion complex or encounter pair, whereas the subsequent step is of arenium ion nature (separate for the ortho, meta, and para positions). The former determines substrate selectivity, whereas the latter determines regioselectivity. Thermal free radical nitration of benzene and toluene with tetranitromethane in sharp contrast gave nearly statistical product distributions.

Synthesis, X-ray crystal structure, and chemistry of the cation [(η-MePh)Mo(µ-SMe)4Mo(η-MePh)]2+; easy D2O–NaOD catalysed H–D exchange of the methyl hydrogens of a η-bonded toluene ligand

Treatment of the new paramagnetic cation [(η-PhMe)Mo(py)3]+(py = pyridine) with methane thiol yields the redox active, diamagnetic cation [(η-PhMe)Mo(µ-SMe)4Mo(η-PhMe)]2+ which undergoes complete deuterium exchange of the toluene methyl hydrogens in D2O–Na3PO4 buffer (pD = 11) at 25 °C and which yields the weakly paramagnetic cation [(MeIm)3 Mo(µ-SMe)3-Mo(MeIm)3]3+(MeIm = 1-methylimidazole) on reaction with zinc amalgam in 1-methylimidazole–acetonitrile solution.

Electrochemical production of OH. radicals and their reaction with toluene

The reaction between electrochemically generated Fenton's reagent and toluene was studied. The products arising from this reaction system were consistent with a primary hydrogen atom abstraction from the methyl group of toluene to give benzyl radicals.

The anomalous low temperature relaxation of methyl protons

The frequency dependence of the low temperature T 1 minimum for the toluene methyl protons in p-t-butyltoluene and the fact that no low temperature minima have been observed for compounds having intramolecular rotational barriers with three-fold symmetry suggest that quantum mechanical tunnelling may not make an important contribution to the proton spin relaxation. A stochastic model for rotation in a potential barrier having both three- and six-fold symmetry terms is proposed.

Alkylation on synthetic zeolites: III. Alkylation of toluene with methanol and formaldehyde on alkali cation exchanged zeolites

Alkylation of toluene with methanol and with formaldehyde was studied over the alkali cation exchanged zeolites. It was found that xylenes were formed by alkylation of the benzene ring of toluene on Li exchanged zeolites. However, a mixture of styrene and ethylbenzene was formed by the alkylation of the methyl group of toluene on Na, K, Rb and Cs exchanged zeolites, and each alkylation proceeded very selectively. Formaldehyde was more reactive than methanol in both alkylations, but gave similar aromatic products to that of methanol. Under the optimum conditions in the alkylation with formaldehyde, the yields of styrene and ethylbenzene were 10.3 and 2.6% on RbX catalyst, respectively, and the yield of xylenes was 10.7% on LiY catalyst. The yield of the alkylation products of the benzene ring of toluene was related to the weak acidity of Li zeolites, and was depressed by a basic reagent. On the other hand, the yield of the alkylation products of the methyl group of toluene was depressed by an acidic reagent, and was not poisoned by aniline. Further, it was detected that K and Rb zeolites have solid basicity. It is therefore suggested that the formation of xylene and that of both styrene and ethylbenzene depends on the catalyst acidity and basicity, respectively.

Electrochemical oxidation of aliphatic polynitro compounds

Trinitromethyl radicals formed in the electrooxidation of the trinitromethane anion are capable of stripping a hydrogen atom from the methyl group of toluene, as well as recombining with the benzyl and methyl radicals, forming the corresponding trinitro derivatives.

INDO Molecular Orbital Calculations on the Conformational Dependence of Long-range Spin–Spin Coupling of Methyl Protons in Toluene, p-Fluorotoluene, and the Xylenes

The conformational dependence of the nuclear spin–spin coupling from methyl protons to ring protons, to the fluorine nucleus, and to protons of other methyl groups in toluene, p-fluorotoluene, and the xylenes is computed by the finite perturbation technique in the INDO approximation of molecular orbital theory. The calculated coupling over six bonds to the proton in the para position agrees quantitatively with experiment and its predicted dependence on the rotational angle of the methyl group supports a commonly assumed π electron mechanism for the transmission of spin information between the nuclei. Similar remarks apply to the fluorine nucleus in p-fluorotoluene. The couplings over five and four bonds to the protons in the meta and ortho positions display a more complex angular dependence and the former can be interpreted in terms of a dominant σ electron mechanism. The coupling between protons in different methyl groups in the ortho and meta xylenes is calculated as rather larger than the values observed in their derivatives and in the main shows the behavior expected from a π electron mechanism. Those conformations of ortho xylene in which the coupled protons are in close proximity yield computed values plausibly attributable to "direct" and/or "through-space" mechanisms. The preferred conformation of the methyl group in toluene is predicted to have a C—H bond eclipsing the plane of the aromatic ring and the calculated barriers to rotation of 0.013 kcal/mol in toluene and of 0.014 kcal/mol in p-fluorotoluene are in quantitative accord with microwave data.

Biochemical Oxidation of Methyl Group of Toluene and its Para‐Substituted Derivatives in the Housefly and the Egyptian Cotton Leafworm

AbstractThe ring‐methyl in vivo oxidation was investigated in the housefly and Egyptain cotton leafworm. Conversion of the methyl into a carboxy group occurred in both housefly adults and Egyptain cotton leafworm larvae. The oxidizing system in the housefly adults was more active than that in the cotton leafworm larvae. The rate of in vivo methyl group oxidation in housefly adults was affected by the p‐substituent in the order nitro > hydrogen > amino > methoxy, while in the cotton leafworm larvae was hydrogen > nitro > amino > methoxy. A linear relationship was found between the Hammett's substituent constants and the rates of in vivo oxidation in the housefly.ZusammenfassungBiochemische Oxydation von Methylgruppen und parasubstituierten Derivaten des Toluens im Körper der Hausfliege und der BaumwolleuleDie Umwandlung von Methyl in eine Carboxyl‐Gruppe ging im Körper beider Insektenarten vor sich. Dabei war das Oxydationssystem in den Imagines der Hausfliege aktiver als in den Raupen der Baumwolleule. Die Oxydationsrate in den Fliegen wurde von p‐Substituenten in der Reihenfolge ihrer Beeinflussungsstärke: nitro > hydrogen > amino > methoxy beeinflußt, während die Reihe bei den Eulenraupen: hydrogen > nitro > amino > metoxy lautete. Es wurde eine lineare Beziehung zwischen der Hammettschen Substitutionskonstanten und der Oxydationsrate in der Hausfliege gefunden.

Synthesis of Photosensitive Polymers by the Condensation Reactions of Poly(2-hydroxyalkyl acrylate) with Cinnamoyl Chloride

New photosensitive polymers which have high sensitivities and low softening temperatures were prepared by the condensation reactions of poly(2-hydroxyethyl acrylate)(PHEA), poly(2- hydroxypropkyl acrylate)(PHPA) and 2-hydroxyethyl acrylate-vinyl acetate copolymer(PHEAVAc) with cinnamoyl chloride.Polymerization of 2-hydroxyethyl acrylate could be conducted in water or in aprotic polar solvents such as hexamethyl phosphoramide(HMPA). The condensation reaction of PHEA with cinnamoyl chloride proceeded easily in HMPA and the reaction product was soluble in organic solvents such as toluene and ethyl methyl ketone, but the product obtained by the Schotten-Baumann reaction changed to an insoluble material after drying. This might be attributable to an intermolecular transesterification of PHEA occured as a side reaction. Polymerization of 2-hydroxypropyl acrylate and copolymerization of 2-hydroxyethyl acrylate and vinyl acetate were conducted in HMPA and the condensation reactions of the polymers thus obtained with cinnamoyl chloride were carried out in HMPA.The photosensitivities of these polymers containing 5 wt % of 5-nitroacenaphthene as sensitizer were found to be ca.2∼8 times higher than that of KPR, which is a commercially available photosensitive resin made from polyvinyl cinnamate.The softening temperatures of the polymers were 45∼60°C and were lower than that of polyvinyl cinnamate(107°C).