Dilute Benzene Research Articles

Dipole moment of N-(p-methoxybenzylidene)-p-butylaniline

The dipole moment of N-(p-methoxybenzylidene)-p-butylaniline (MBBA) has been determined in dilute benzene solution as 7.34 × 10–30 C m. Its decrease with rising concentration leads to an equilibrium constant for molecular aggregation in solution. Dipole moment evaluation for the nematic and isotropic phases of pure MBBA show that there is no significant change in the state of the polar molecules at the phase transition. Dielectric relaxation studies on dilute benzene solution of MBBA and on the isotropic liquid phase show that the relaxation is as expected from the reorientation of a rigid molecule.

Organolithium cleavage of aliphatic polyethers, polysulfides and polyimines

AbstractOrganolithium compounds and other Group IA organometallics cleave high molecular weight poly(alkylene oxides) very rapidly at room temperature in dilute benzene solution. This reaction also works on a dimeric polyepoxide such as bis(2‐n‐butoxyethyl)ether and much less readily on a monomeric one as 1,2‐dimethoxyethane. On the other hand, a simple aliphatic monoether such as di‐n‐butyl ether is not cleaved under conditions several orders of magnitude more drastic than were effective on the polyethers. The mechanism for this facile polyether cleavage is proposed as a β‐elimination in which the organolithium is greatly activated by chelation with the main‐chain oxygen atoms of the polyether. This cleavage method has been used broadly on high molecular weight polyethers to obtain quantitative yields of hydroxyl‐ended, amorphous, and crystalline polyethers (Mn = 500–10,000), many of which cannot be made by direct polymerization. Aliphatic polysulfides and an N‐substituted aliphatic polyamine cleave by this same method to, respectively, mercapto‐ended and secondary amine‐ended polymers. The mechanism aspects of these results are discussed.

Electric Moments and Conformations of ortho-, meta-, and para-Fluorobenzaldehyde

The dipole moments of ortho-, meta-, and para-fluorobenzaldehyde were determined in dilute benzene solutions at 25 °C. The experimental data are in complete agreement with the conclusions reached by Wasylishen and Schaefer (1), viz. the O-trans conformer is the more stable conformer for ortho- and meta-fluorobenzaldehyde.

Proton spin – lattice relaxation time of aniline-d2 in deuterated benzene and deuterated aniline solution

The proton spin – lattice relaxation time of aniline-d2 in deuterated aniline solution was determined as a function of concentration and temperature over the temperature interval 260–360 °K using a pulsed nuclear magnetic resonance technique. In addition the proton spin – lattice relaxation time of aniline-d2 in deuterated benzene solution at 20 °C was also determined. It was found that the activation energies of the intra- and inter-molecular relaxation rates were of similar magnitude, viz. 4.5 and 4.4 kcal/mole, respectively. It was also found that at 20 °C the rotational correlation time, τr, of the C6H5NH2 molecule in infinitely dilute perdeutero benzene solution was approximately half that of the partially deuterated aniline molecule, viz. 3.0 × 10−12 and 6.3 × 10−12 s, respectively, and that τr of C6H5ND2 in infinitely dilute perdeutero aniline solution is much larger than in infinitely dilute perdeutero benzene solution and is equal to 19 × 10−12 s.

Dilute Solution Properties of Monodisperse Poly(α-methylstyrene). II. Hydrodynamic Properties in Good Solvents

Hydrodynamic properties of monodisperse poly(α-methylstyrene) were studied in dilute benzene solutions, both concentration and molecular weight being varied. Molecular weight determination was performed by three methods, osmometry, light scattering and sedimentation equilibrium. The intrinsic viscosity was found to be [η]=(1.034±0.05)×10−4 M0.72 dl/g at 30°C, where M is the molecular weight. The sedimentation coefficient extrapolated to zero concentration and one atmosphere was found to be s0°=(3.61±0.03)×10−15 M0.43 sec. The Scheraga-Mandelkern constant β was evaluated as (2.43±0.03)×106 which was independent of M and in agreement with the value previously obtained in theta solvent. The concentration dependence of sedimentation coefficient was found to be compatible with the recent theory by Pyun and Fixman.

Intermolecular association in structured liquids 1. Ethylene carbonate and N-methylacetamide

Association constants of ethylene carbonate and N-methylacetamide have been calculated from measurements in dilute benzene solutions using a vapor pressure osmometer. The first association constants, K 12, are 1.10 and 3.30 mol kg −1 respectively. The constants for subsequent association are 1.58 and 7.63 mol kg −1, respectively. The extension of these results to concentrated solutions using the isopiestic method indicates that pure liquid ethylene carbonate has an average of 8.3 monomer units per “cluster”. The chain length of N-methylacetamide increases to 8 or 9 units in 4 to 6 mol kg −1 solutions in benzene and then decreases due to steric interference. The average chain length appears to be about 4.8 units in the pure liquid.

Azomethine derivatives. Part X. 1,1,3,3-Tetramethylguanidine adducts of trimethylaluminium, triethylaluminium, and aluminium trichloride: dimethyl-, diethyl-, and dichloro-bis(dimethylamino)methyleneamino-aluminium

The adducts (Me2N)2C:NH,AlX3(X = Me or Et), from (Me2N)2C:NH +½(or more) Al2X6 in hexane, are monomeric in dilute benzene solution and are believed to have a structure co-ordinated through the imino-nitrogen. They lose XH when heated, forming [(Me2N)2C:NAIX2]2, for which four-membered ring structures are suggested. Although the adduct (Me2N)2C:NH,AlCl3 does not similarly afford [(Me2N)2C:NAICl2]2 when heated, the latter can be prepared from (Me2N)2C:NLi and AlCl3. I.r. spectroscopic details are given for all these new compounds. Also discussed are the 1H n.m.r. spectra of the alkylaluminium compounds and the mass spectra of (Me2N)2C:NH,AICl3 and [(Me2N)2C:NAIEt2]2.

Microwave absorption and molecular structure in liquids. LXXVI. Relaxation behavior of several primary alcohols in dilute benzene and p-dioxane solutions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicrowave absorption and molecular structure in liquids. LXXVI. Relaxation behavior of several primary alcohols in dilute benzene and p-dioxane solutionsGyan P. Johari and Charles P. SmythCite this: J. Am. Chem. Soc. 1969, 91, 23, 6215–6220Publication Date (Print):November 1, 1969Publication History Published online1 May 2002Published inissue 1 November 1969https://doi.org/10.1021/ja01051a001RIGHTS & PERMISSIONSArticle Views54Altmetric-Citations20LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (609 KB) Get e-Alerts Get e-Alerts

Nuclear magnetic relaxation of 1,2-dichloroethane in deuterated benzene and carbon disulfide solution at 20 °C

The molecular rotational relaxation time of the 1,2-dichloroethane molecule in deuterated benzene and carbon disulfide solution was determined by pulsed nuclear magnetic resonance techniques. It was found that the rotational relaxation time, τr, in infinitely dilute deuterated benzene solution and in infinitely dilute carbon disulfide solution was 1.3 × 10−12 and 0.6 × 10−12 s, respectively. Both values are in fair agreement with the dielectric molecular relaxation time for 1,2-dichloroethane in dilute benzene, p-xylene, and n-hexane solution reported by Chitoku and Higasi (1).

Molecular rotational relaxation time of aniline in deuterated benzene solution at 20 °C

The molecular rotational relaxation time of the aniline molecule in deuterated benzene solution was determined at 20 °C by pulsed nuclear magnetic resonance (n.m.r.) techniques. It was found that the rotational relaxation time, τr, in infinitely dilute deuterated benzene solution was 3.2 × 10−12 s, a value which is in fair agreement with the dielectric molecular relaxation time reported by Grubb and Smyth for aniline in dilute benzene solution.

Electric dipole moments of ortho-, meta-, para-, and penta-fluorostyrene molecules

The dipole moments of ortho-, meta-, para-, and penta-fluorostyrene were determined in dilute benzene solution at 25 °C. It was found that the magnitude of the molecular dipole moment depends on the position of the fluorine atom in the benzene ring.

Electric moments and conformation of substituted fluoroformates in benzene solutions

The dipole moments of methyl-, ethyl-, n-propyl-, n-butyl-, n-amyl-, and phenyl-fluoroformate were determined in dilute benzene solutions at 25 °C. The experimental results suggest that the conformation of the fiuoro-esters is similar to the conformation of the chloro-esters and differs from the conformation of the normal esters; viz. the ester hydrocarbon group and the fluorine atom are cis to each other. Results of fluorine and proton n.m.r. measurements on these molecules support the conclusions based on the dipole moment data if a "through-space" coupling mechanism is assumed for the long range spin–spin coupling JH–F1−5.

Dipole moments of some molecules in dilute benzene solutions

The dipole moments of bromochloromethane, bromodichloromethane, bromotrichloromethane, dimethylcarbamyl chloride, dimethylcarbamyl fluoride, vinyl formate, phenyl chlorothiolformate, γ-valerolactone, and 2-iodopropene were determined in dilute benzene solutions at 25 °C. The observed magnitudes of the dipole moments are rationalized in terms of molecular electronic charge distributions.

The Molar Kerr constants and anisotropic polarisabilities of certain sterically hindered aromatic nitro-compounds

The Molar Kerr constants and dipole moments, measured at infinite dilution in benzene, of the polar substances 1,4-dibromo-2-nitrobenzene, 1,3,5-tribromo-2-nitrobenzene, 1,3,5-trichloro-2-nitrobenzene, 1,2,4,5-tetramethyl-3,6-dinitrobenzene, 4-acetyl-1-t-butyl-3,5-dimethyl-2,6-dinitrobenzene, 1-t-butyl-3,5-dimethyl-2,4,6-trinitrobenzene, 1-nitronaphthalene, and 1,8-dinitronaphthalene are recorded. Molar Kerr constants and dielectric polarisations in benzene solution are also reported for the non-polar molecules p-dibromobenzene, 1,3,5-tribromo-benzene, 1,3,5-trichlorobenzene, and naphthalene. The anisotropic polarisabilities of the C–NO2 group derived from aliphatic and aromatic environments are used in conjunction with the polarisability tensor specifications of certain basic structural units in a discussion of the conformation of the aromatic nitro-compounds mentioned. The results are in general agreement with predicted steric and electromeric effects.

Dipole moments of substituted chloroformates in dilute benzene solutions

The dipole moments of methyl, ethyl, n-propyl, n-butyl, amyl, and phenyl chloroformate as well as n-butyl formate in dilute benzene solution at 25 °C were determined. The experimental results suggest that the configuration of the chloro-esters differs from the configuration of the unchloroinated esters, viz. the ester hydrocarbon group and the chlorine atom are cis to each other.

Configuration of methyl formate in benzene and carbon disulfide solutions

The dipole moment of methyl formate in dilute benzene and carbon disulfide solution at 25 °C was determined. The obtained value for the dipole moment was compared with the measured value of β-butyrolactone derived from dilute benzene solution. It is concluded that the preferred configuration of methyl formate in CS2 solution does not correspond to that assumed by Pendred et al. in their calculations of spin-lattice proton relaxation times in methyl formate dissolved in CS2, but to that postulated by Curl, Jr. from microwave data.

Studies on dialkyltin diacetate derivatives

A series of dialkyltin diacetates and their derivatives, R 2Sn(OAc) 2, [(AcO)R 2Sn] 2O and (AcO)R 2SnOSnR 2(OH) (RCH 3, C 2H 5, n-C 3H 7, n-C 4H 9), have been prepared. Dialkyltin diacetates are monomeric in benzene,having a nonsymmetrically chelated octahedral configuration; bridging of acetoxy groups seems to occur in the neat liquid or in the crystalline state. The compounds [AcO)R 2Sn] 2O are dimeric at moderate concentrations and dissociate to monomers in dilute benzene and chloroform solutions. This change is reflected in changes of the CO 2 and SnO infrared bands. The dimeric methyl compound showed two tin-methyl proton chemical shifts with a small difference. Molecular weight of (AcO)(C 4H 9) 2SnOSn(C 4H 9) 2(OH) increases with concentration from that of dimer. This seems to be caused by the bridging of the acetoxy groups among dimers.

Crystallized state, thickening process, and crystal transformation of single crystal of trans-1,4-polybutadiene

Abstract The effect of heat treatment of trans-1,4-polybutadiene single crystals prepared from dilute benzene solution was studied by dilatometry, X-ray diffraction, and dynamic viscoelastic measurement. The crystal transformation temperature of the single crystal is 55.5[ddot]C, 20[ddot]C lower than that of the bulk crystallized sample. After heat treatment of the single crystal above 55.5[ddot]C, their crystal transformation temperature increases to 69.5[ddot]C. At the same time, thickening of the lamellae suddenly occurs and the viscoelastic primary absorption observed in the single crystal mat disappears. It is suggested that this means that the amorphous region attached to the single crystal rapidly crystallized above this temperature, in particular the loose loops attached to the end surface of the crystal are dragged into the crystalline phase to form tight loops as a result of the sliding diffusion of molecules along their axes. This is accompanied by the sudden thickening of the lamellae at the c...

Dipole moments of some ethylene derivatives

The dipole moments of the ethylene derivatives acrylonitrile, chloroacrylonitrile, methyl vinyl ketone, vinyl bromide, 1,1-dichloroethylene, and tribromoethylene were determined in benzene solution at 20 °C. The measured dipole moments were corrected for the solvent effect by the method of Looyenga. In addition the applicability of the Looyenga equation for the solvent effect was tested on earlier reported data for 20 different molecules, whose dipole moments were derived from dilute benzene and carbon tetrachloride solutions, respectively. The corrected dipole moment values were compared with earlier corrected values calculated according to the method of Le Fevre and Le Fevre and with reported gas values. It was found that for most compounds both methods of correction yielded dipole moment values which differed by 0–10% from the gas values.

Applications of limiting conversion free‐radical polymerizations. II. Azobisisobutyronitrile‐initiated polymerization of methyl methacrylate in benzene

AbstractData for the azobisisobutyronitrile‐initiated polymerization of methyl methacrylate in dilute benzene solution is presented at 80, 100, and 126°C. in terms of Tobolsky's limiting conversion kinetics. Number‐average molecular weights were obtained viscometrically. Attempts to evaluate the relative amounts of combination and disproportionation in the chain‐terminating reaction were foiled by the discovery that under the conditions reported the initiator efficiency is temperature‐dependent decreasing markedly with increasing temperature.