Aromatic Hydrocarbon Solvents Research Articles

Determination of total aromatic constituents in petroleum products by induced 1H-nuclear magnetic resonance chemical shifts.

1H-NMR chemical shifts of 1, 1, 2-trichloroethane in various types of aliphatic hydrocarbon solvents(n-types, branched types and cyclic types) and aromatic hydrocarbon solvents(benzene substitution compounds) were measured. In the spectrum of 1, 1, 2-trichlo-roethane dissolved in aliphatic hydrocarbons the CH2 and CH proton signals are approximately constant. On the other hand, in the case of 1, 1, 2-trichloroethane dissolved in aromatic hydrocarbons, their proton signals were induced at up-field by the magnetic anisotropy effects of aromatic rings. The relationship between the magnitude of the up-field shifts of the protons of 1, 1, 2-trichloroethane and the concentration of aromatic constituents was discussed in view of the determination of aromatic constituents in petroleum products. The magnitude of up-field shifts of the protons in 1, 1, 2-trichloroethane is related to the contents of aromatic constituents. Therefore, it was found that the results above-mentioned is applicable to the determination of aromatic constituents in petroleum products. This method is simple and rapid determination of the total aromatic constituents in petroleum products.

The diphenylmagnesium/alkali metal alkoxide system. Hydrocarbon-soluble organoalkali metal reagents

Unsolvated diphenylmagnesium is solubilized in aromatic hydrocarbon solvents by an alkali metal 2-ethoxyethoxide. The mode of interaction between Ph 2Mg and MOCH 2CH 2OEt (M = Li, Na, K) varies with M. For M = Li the complex formed has an Mg/Li ratio equal to 1.3/1.0, and is evidently different from the PhLi/Mg(OCH 2CH 2OEt) 2 complex. For M = Na, the metal—metal interchange apparently leads to a complex identical to that derived from PhNa and Mg(OCH 2CH 2OEt). For M = K the results are not conclusive. The width of the resonance 13C from the ipso-carbon, increases with increasing ionic radius, and for M = K the signal is too broad to be clearly observed. The ipso-carbon in the NMR spectrum of the PhNa/Mg(OCH 2CH 2OEt) complex has now been shown to give rise to resonance at 175.95 ppm. Metalation experiments involving Ph 2Mg along with two equivalents of MOCH 2CH 2OEt indicated that reactivity increases in the order Li < Na < K.

Effect of the internal reference on ASIS correlations: 3—Intrinsic ASIS of formyl protons

AbstractThe intrinsic ASIS of formyl protons in p‐X‐benzaldehydes, dimethylformamide and diphenylformamide in a series of aromatic hydrocarbon solvents have been calculated. These values of Δ¯xα of the formyl protons present excellent correlations in aromatic hydrocarbon solvents, and are factorizable into solute and solvent factors Ux and Vα, respectively. The Ux values are linearly related to the value of σp of the substituent in the solute. The Vα values depend on the substitution pattern of the benzene ring of the solvent molecules.

The effect of the internal reference on ASIS correlations: 2—The intrinsic ASIS of TMS protons in aromatic hydrocarbon solvents

AbstractA method is developed to calculate the intrinsic ASIS of TMS protons used as internal reference, based on linear correlation of the ASIS of a group of sensor protons in two fixed aromatic solvents. Several solute systems (p‐X‐benzaldehydes, camphor, α‐Br‐camphor, 5‐X‐furfurals, p‐X‐acetophenones and methyl ketones) are used to calculate a series of intrinsic ASIS values of TMS in 12 aromatic hydrocarbon solvents. The Δα TMS values are used, in turn, to calculate the intrinsic ASIS of CHO protons in dimethylformamide and diphenylformamide, and of the CH3 protons in diethyl ether and diisopropyl ether.

Transition metal-promoted reactions : VII. Novel reactions of acid chlorides with pentacarbonyliron in aromatic solvents

Upon treatment with Fe(CO) 5 in an aromatic hydrocarbon solvent aromatic acid chlorides gave an mixture of triarlmethane and tetraarylethane. The reaction may proceed via benzaldehyde and diarylmethanol intermediates. A free radical mechanism is proposed.

The effect of solvent on exciplex emission from pyrene—tributylamine and anthracene—tributylamine systems

The exciplex emissions from the pyrene—tributylamine (TBA) and anthracene—TBA systems have been found to undergo a red shift in solvents of higher dielectric constants. From these shifts it has been estimated that the extent of charge transfer is 66% in the pyrene—TBA system, while it is over 80% in the anthracene—TBA system. In aromatic hydrocarbon solvents the exciplex emission was found to undergo a red shift and an intensification in the order benzene > p-xylene > mesitylene. This has been attributed to triple exciplex formation, for which the equilibrium constants between the exciplex and the aromatic solvents have been found to be 3.2 × 10 −2 (benzene), 2.2 × 10 −2 ( p-xylene) and 2.2 × 10 −2 (mesitylene) for the pyrene—TBA system, while for the anthracene—TBA system the equilibrium constants were 8.3 × 10 −3 (benzene) 8.3 × 10 −3 ( p-xylene) and 6.6 × 10 −3 (mesitylene). A tentative explanation for the effect of aromatic hydrocarbon solvents on exciplex emission has been suggested. In alcoholic solvents the exciplex emissions were blue shifted owing to the formation of hydrogen bonded complexes between the exciplex and the alcohols. The pyrene—TBA system forms much stronger hydrogen bonds with alcohols than the anthracene—TBA system. This was considered to indicate the participation of the lone pair electrons at the nitrogen of TBA in hydrogen bond formation.

Photochemical reactions of anthraquinone with hydrocarbons in the presence and absence of oxygen: Trapping of radical intermediates

Radical intermediates formed at 25°C in the presence and absence of oxygen during the photolysis of anthraquinone in aromatic, cyclic and aliphatic hydrocarbon solvents were trapped by 2,6-dichloronitrosobenzene, 2,6-dibromonitrosobenzene and 2,4,6-tribromonitrosobenzene. The resulting nitroxide radicals have been characterized “in situ” by ESR spectra.

The tissue distribution and clearance of Aerotex 3470, an aromatic hydrocarbon solvent

The tissue distribution and clearance of Aerotex 3470, an aromatic hydrocarbon solvent

The reaction of intermediate zirconocene-aryne complexes with CH bonds in the thermolysis of diarylzirconocenes

Upon thermolysis in aromatic hydrocarbon solvents diarylzirconocenes undergo successive replacement of their σ-bonded ligands by aryl groups from the solvent. Analysis of the product mixture by photochemical degradation to biphenyls reveals that intermediate aryne zirconocene complexes are formed which then react with the solvent with CH bond fission and formation of new ZrC bonds. A β-hydride elimination process can be excluded for the formation of the aryne complexes and it is suggested that they are formed via abstraction of an ortho proton from one of the aryl ligands by the other σ-bonded group.

ChemInform Abstract: THE PHOTOREACTIONS OF BENZOPHENONE IN AROMATIC HYDROCARBON SOLVENTS

Chemischer InformationsdienstVolume 6, Issue 11 Preparative Organic Chemistry ChemInform Abstract: THE PHOTOREACTIONS OF BENZOPHENONE IN AROMATIC HYDROCARBON SOLVENTS R. S. DAVIDSON, R. S. DAVIDSONSearch for more papers by this authorR. WILSON, R. WILSONSearch for more papers by this author R. S. DAVIDSON, R. S. DAVIDSONSearch for more papers by this authorR. WILSON, R. WILSONSearch for more papers by this author First published: March 18, 1975 https://doi.org/10.1002/chin.197511149Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume6, Issue11March 18, 1975 RelatedInformation

Dissolution of Alkali Metals in Aromatic Hydrocarbon Solvents by Cryptate Formation

Dissolution of Alkali Metals in Aromatic Hydrocarbon Solvents by Cryptate Formation

On the possibility of chain folding in solutions of normal paraffins and polyethylene

AbstractA simple statistical thermodynamic argument is presented in which the probability of intramolecular chain folding of normal paraffins and polyethylene in solution is examined. This possibility is based on the existence of low‐energy intramolecular conformations which are stable enough to overcome the tendency of a chain molecule to assume a random arrangement in solution. Some rough estimates of the magnitudes of energetic interaction in straight‐chain hydrocarbons are made to demonstrate the plausibility of this hypothesis. The experimental support for this model arises from NMR spectra of normal paraffins in aromatic hydrocarbon solvents.

Syndiotactic polymerization of methyl methacrylate

AbstractTypical Ziegler‐type catalysts derived from AIR3 and TiCl4 were found to be effective in the syndiotactic polymerization of methyl methacrylate at low temperatures. The influences of polymerization variables on the polymer yield, the molecular weight of the polymer produced, and the syndiotactic regulating capacity of the catalysts were investigated. In general AlEt3/TiCl4 molar ratios of 3:10 mixing of both the catalyst components and aging of the catalyst system in the temperature range of −30 to 30°C. using aromatic hydrocarbon solvents such as toluene as a polymerization medium, and low polymerization temperature, such as −78°C. are the preferred conditions for the formation of syndiotactic, high molecular weight poly(methyl methacrylate) in high yield. From the results of testing catalyst activities of the separated catalyst systems it was concluded that some cooperation between AIR3 and the insoluble Ti halide compound obtained by the reduction of TiCl4 with AIR3 is essential for the formation of syndiotactic poly(methyl methacrylate).

Liquid-phase photolysis. Part XIII. Charge-transfer transitions in complexes of benzene and alkylbenzenes with tetracyanoethylene, p-chloranil, and maleic anhydride: use of the aromatic donors as solvents

U.v. and visible charge-transfer absorption spectra have been examined for dilute solutions of tetracyanoethylene, p-chloranil, and maleic anhydride in benzene and various alkylbenzenes, using very short liquid-path lengths where necessary. Tetracyanoethylene and p-chloranil were found to be essentially completely complexed in such solutions, and it appears that the extinction coefficients of the complexes can be measured directly without recourse to graphical procedures of the Benesi-Hildebrand type. These extinction coefficients show no marked dependence on donor strength or steric effects, and most lie in the range 2000–3000 cm.–1 mol–1 l.In contrast, the weaker acceptor maleic anhydried is incompletely complexed in liquid aromatic-hydrocarbon solvents. The degree of complexing appears to be determined both by the donor strength and steric effects. Since alkyl substituents increase the donor character of the benzene ring while decreasing its accessibility, the extent to which an alkylaromatic hydrocarbon complexes with maleic anhydride reflects a compromise.The relevance of these results to the photochemistry of the corresponding systems is discussed.

The Influence of Excimer Formation on Solvent-Solute Energy Transfer in Organic Liquid Scintillators

Excimer (excited dimer) formation occurs in all the aromatic hydrocarbon solvents used in liquid scintillators. The influence of this process on solvent-solute energy transfer has been studied for a model system: 9, 10-diphenyl anthracene (DPA) in 1, 6-dimethyl naphthalene (DMN), diluted by n-heptane (Hp). Data on the fluorescence lifetimes, spectra and quantum yields and the viscosity of DMN in Hp are used to analyze the results. It is found that the energy transfer rate parameters of the excited monomer and excimer differ, but that they are independent of Hp dilution. The influence of diffusion and solvent energy migration on solvent-solute energy transfer are discussed, and a migration mechanism involving excimer formation and dissociation is proposed.

An inexpensive, high flash-point, low toxicity liquid scintillator of high efficiency

Studies were made of commercially available aromatic hydrocarbon solvents with high transparencies and flash points for use as scintillator solvents. The most suitable was found to be technical grade Shellsol A, consisting almost entirely (98.3%) of alkylbenzenes (predominantly the triethyl benzenes). The remaining paraffins (1.1%), olefins (0.3%) and naphthenic compounds (0.3%) apparently had no deleterious effects. This solvent had a scintillation efficiency about 95% that of toluene, and for the more energetic radiation there was a suggestion that it becomes slightly more efficient. (M.C.G.)

Reactions of unsaturated fatty alcohols. VII. Polymerization of vinyl ethers catalyzed by stannic and ferric chlorides

SummaryVariables affecting the use of stannic chloride as a catalyst for initiating polymerization of conjugated and nonconjugated soybean vinyl ether were studied. Molecular weight of the polymers increased with an increase in catalyst and a decrease in initiation temperature, and it decreased when the amount of moisture in the solvent, the amount of free fatty alcohol in the monomer, or the ratio of solvent to monomer was increased. Aromatic and aliphatic hydrocarbon solvents were superior to halogenated solvents for conducting polymerizations. Similar results were obtained with nonconjugated monomers except that viscosities of the polymers were considerably lower than those of polymers of the same molecular weight obtained from conjugated monomer.To obtain polymers suitable for film‐forming studies (4,000–6,000 molecular weight) polymerization is initiated preferably at 25°C. with 3 ml. of anhydrous toluene used per gram of monomer and 4.8 mmoles of stannic chloride per mole of monomer. Monomer purity should be at least 98%.Ferric chloride hexahydrate initiated polymerization at 25°, but polymerization was incomplete, and the polymers had relatively low molecular weights.

Infrared Study of the Effect of Solvent upon ν(NH) in Pyrrole

New data are presented on the NH group stretching frequency of pyrrole in dilute and concentrated solutions in fourteen different solvents and in several solvent mixtures. It is shown that in nonpolar solvents ν(NH) of pyrrole obeys the Kirkwood-Bauer relationship, δν/ν=C(D—1)/(2D+1), where C is a constant, and D is the solvent dielectric constant. Furthermore, it is shown that C is only slightly affected as ν(HCl) of hydrochloric acid, ν(OD) of methanol-d, or ν(OH) of methanol, ethanol, propanol, or phenol is substituted for the ν(NH) of pyrrole. The deviations from the Kirkwood-Bauer relationship produced by polar solvents and aromatic hydrocarbon solvents are analyzed in terms of hydrogen bonding and the formation of molecular complexes. The effect of solvent upon band intensity is also briefly examined. A classification of types of OH and NH solution frequencies is suggested.