Cyclohexanone Solution Research Articles

Surface complexes of cyclohexanone and aqueous solution of NH3 on Ti-silicalite in liquid phase

On the surface of the SiO2 catalyst used in the ammoximation of cyclohexanone to cyclohexanone oxime in the gaseous phase the formation of the imine group (supposed precursor in the reaction) was found previously. The authors investigated the possibilities of the occurence of the imine group on Ti-silicalite used as catalyst in the same reaction when performed in liquid phase. The technique using Ti-silicalite (previously treated with H2O2) suspension in cyclohexanone, NH4OH or their 1∶1 mixture dried on an irtran disc gave the possibility of indicating the formation of surface adsorption complexes by IR spectroscopy. The appearance of a band at 1654 cm−1 corresponding to υ(C=N) after the adsorption of cyclohexanone together with NH4OH indicates the formation of the imine group, whereas the simultaneous lowering of the intensity of the band 970 cm−1 (Ti-O vibration) indicates that the Ti centres take part in this process.

Solution process of suspension poly(vinyl chloride) in cyclohexanone by means of a viscometer

AbstractTo study the structure of grains of suspension poly(vinyl chloride) (PVC), the authors applied a capillary viscometer for cyclic measurements of viscosity of the PVC–cyclohexanone solution during dissolution of the polymer. Final concentration of the solution was 0.5–1.0 g/100 cm3 and the measurements were made at temperatures of 313, 333, 353, and 373 K. It was found that at 353 K, a temperature close to the glass transition temperature of PVC, the curve describing changes of viscosity vs. the dissolution time has a pronounced maximum. It follows from a preliminary analysis of the obtained results that this maximum corresponds to the viscosity of a PVC solution in which average apparent mass is many times larger than true average molecular mass of the studied sample. It mans that into the solution enter single chains and some formations, called microdomains in the literature, that are composed of tens of macromolecules. The microdomains disintegrate later to single macromolecules.

Orientation of poly(3-alkylthiophene) on polyethylene crystals

Poly(3-alkylthiophene)s (P3ATs) are conductive polymers soluble in many organic solvents. The number of carbon atoms (n) in the linear side chain in P3ATs used in this study was 6, 8, and 12. We concentrate on the result of P3HT (n=6), since similar results were obtained for the other two cases. In this paper we will report the molecular packing in P3HT whisker, and also the morphology and orientation of P3HT epitaxial growth on polyethylene (PE) crystals.P3HT whiskers were grown from a dilute solution of cyclohexanone while cooling the solution to room temperature. The color of the solution changed to red from yellow as the whiskers were formed. P3HT whiskers were also grown in cyclohexanone solution on PE single crystals mounted on a Cu grid supported by carbon film. Ultra-high molecular weight (UHMW) PE (Mw=4x106) gel film was uniaxially stretched (draw ratio=100). The drawn gel film was dipped into a xylene solution of P3HT at room temperature in order to crystallize the P3HT molecules onto the PE crystal. The samples were examined by a transmission electron microscope (TEM) at 80 kV.

Effect of an external magnetic field on photolysis of aqueous solutions of cyclohexanone

The effect of an external magnetic field on the ratio of the yields of the basic products of photolysis of aqueous solutions of cyclohexanone was investigated by high-resolution NMR spectroscopy. It was shown that the magnetic field does not significantly affect the yield of the products of the reaction with a 0.2 M concentration of the starting ketone, the yield of 5-hexenal decreases, and the yield of caproic acid and the rate of photolysis increase below 0.02 M. The observed effects are explained by association of cyclohexan-one with involvement of the HFI mechanism from the theory of “radical pairs.”

Isotope effect in the gas-phase photolysis of cyclohexanone

An isotope effect was found for the carbonyl and α-carbon atom in the gasphase photolysis of cyclohexanone, which is apparently magnetic in nature. This finding additionally indicates that the chemically induced dynamic nuclear polarization in the gas phase in the photolysis of cyclohexanone arises predominantly in biradicals and not in triplet molecules. The separation of isotopes occurs more efficiently in the photolysis of aqueous solutions of cyclohexanone than in the gas phase.

Mechanism of the Carboxylation of Cyclohexanone with Carbon Dioxide Catalyzed by 1,8-Diazabicyclo[5.4.0]undec-7-ene

Abstract The dependence of the rate of carboxylation upon the concentration of the reactant was investigated in dimethyl sulfoxide. The reaction rate depended upon the concentration of cyclohexanone and 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU) in the first order, respectively. The reaction also followed first-order kinetics regarding the CO2 pressure in the range 50–400 Torr. From these reaction characteristics, it is suggested that carboxylation proceeds via a reaction between CO2 dissolved in dimethyl sulfoxide and the anion of cyclohexanone, rather than between the CO2 adduct with DBU and cyclohexanone. The results of carboxylation by the CO2 adduct with DBU and by CO2 dissolved in dimethyl sulfoxide also support the above conclusion. The formation of the cyclohexanone anion by a reaction of cyclohexanone with DBU was verified by the UV spectrum of a solution of concentrated DBU and cyclohexanone.

Infrared spectroscopic studies of hydrogen-bonded complexes of water with oxygen bases—V. The effect of temperature on the OH-stretching bands of water molecules dissolved in some ketones

The infrared spectra, in the OH-stretching region, of H 2O molecules in dilute solution in cyclohexanone and in di- n-propyl ketone have been recorded at a series of temperatures between 15 and 85°C. The observed bands have been resolved into their component absorptions, based on the assignments established earlier, and the effects of temperature on the wavenumbers and their separations, the half-widths and the component intensities have been noted. The results have been interpreted in terms of a shift in the equilibrium between the 1 : 1 and 2 : 1 hydrogen-bonded solvent: water complexes which exist in such solutions.

Effect of Some Solvents on the Radical Polymerization of Methyl Methacrylate Studied by Differential Scanning Calorimetry

Abstract The course of the isothermal polymerization of methyl methacrylate in different concentrated solutions in toluene, n-butyl acetate, cyclohexanone, and dimethylformamide was measured at four temperatures by differential scanning calorimetry. The conversions at the sharp increase of the reaction rate were found to increase with dilution of the reaction mixture. The polymerization enthalpies and the composite rate constants were calculated. The polymerization enthalpies seem to be solvent independent. The composite rate constants for polymerization in butyl acetate are lower and those for polymerization in toluene are equal to the constants for bulk polymerization. They are independent of the concentration of the reaction system. The constants for polymerization in cyclohexanone and dimethylformamide are, however, concentration dependent. An interrelation between the composite rate constants and solubility parameters of the solvents and methyl methacrylate was found. The relative molecular weight av...

Coated wire ion-selective electrodes and their application to environmental problems

Abstract

Studies on the kinetics of dehydrochlorination of poly(vinyl chloride) in solution induced by a weak base

Kinetics of dehydrochlorination of poly(vinyl chloride) (PVC), induced by a weak base such as ammonium hydroxide or n-butylamine ( n.BA) in cyclohexanone solution, were studied by following the disappearance of NH 4OH or n.BA on reacting with the HCl liberated. An overall kinetic scheme was considered and the rate constants of dehydrochlorination under various sets of conditions determined. The initial rate constants ( k 1) of dehydrochlorination at 40°C induced by NH 4OH or n.BA are very close (3.10 × 10 −3 l mol −1 min −1) indicating that NH 4OH and n.BA are comparable in their capacity to induce dehydrochlorination of PVC in solution.

Solution properties of ultra-high molecular weight polymers—13. Viscosity-molecular weight relationships and unperturbed dimensions of poly(butyl methacrylate) in various solvents

The behaviour of ultra-high molecular weight poly(butyl methacrylate) ( M w = 9.59 × 10 6–24.50 × 10 6 ) in dilute solution in methyl ethyl ketone, benzene, dioxane, and cyclohexanone, at 25°C, has been investigated by viscometry. Mark-Houwink relations have been established, and the unperturbed dimensions have been determined and compared with those previously obtained in a θ-solvent.

A visual manifestation of the Norrish Type I reaction: The cyclohexanone sunburn dosimeter

Irradiation of aqueous cyclohexanone solutions produces hex-5-enal and butylketene; the latter reacts with water to form caproic acid, which lowers the pH of the solution and thus can be used to measure the progress of the reaction.

Chronic Toxicity Study of Cyclohexanone in Rats and Mice<xref ref-type="fn" rid="FN2">2</xref><xref ref-type="fn" rid="FN3">3</xref>

A 2-year chronic toxicity assay of cyclohexanone (CAS: 108-94-1) was conducted in F344 rats and (C57BL/6 X C3H)F1 mice by administering a solution of cyclohexanone in drinking water. Two concentrations were given to rats, 6,500 and 3,300 ppm (wt/vol). Male mice received 13,000 and 6,500 ppm, while female mice were given three concentrations, 25,000, 13,000, and 6,500 ppm. Each treatment group consisted of 50 or 52 male and 50 or 52 female rats or mice, except 47 male mice treated with the highest dose and 41 female mice treated with the highest dose, and there was a group of untreated controls of each species. Survival and weight gain were similar to those of controls at the lowest cyclohexanone dose in both sexes of both species, but weight gain was depressed at all of the higher doses. Survival was good (greater than 80% at 90 wk) in all groups except in female mice at the 2 highest doses; at 25,000 ppm of cyclohexanone, only 50% of mice lived beyond 1 year. Most of the neoplasms in the treated groups did not differ significantly in number from those in the controls. Male rats receiving 3,300 ppm cyclohexanone had a 13% incidence of adrenal cortex adenomas (7 animals) compared with an incidence of 2% in controls; the incidence of this neoplasm did not increase in the male rats receiving 6,500 ppm or in the female rats given either dose. The mice had a statistically significant increase in incidence of lymphomas-leukemias among the females given 6,500 ppm, but not among the groups given higher doses of cyclohexanone. Male mice given 6,500 ppm cyclohexanone showed an increased incidence of hepatocellular adenomas and carcinomas, 50% versus 32.5% in controls, but the incidence of these neoplasms was only 37% in the male mice given 13,000 ppm cyclohexanone. The incidence of lymphomas in male mice and of hepatocellular neoplasms in female mice given cyclohexanone did not differ from that in the controls. The evidence for carcinogenic activity of cyclohexanone is marginal and the effect, if any, is weak.

Configurational stereoselectivity in the nucleophilic substitution of poly(vinyl chloride) with sodium thiophenate: NMR study and Monte‐Carlo simulation of the reaction

AbstractThe nucleophilic substitution of the chlorine atoms of poly(vinyl chloride) with sodium thiophenate is assumed to obey an SN2 mechanism with inversion of configuration and a steric control according to which reactivities R of the triads follow the order Rmm > Rmr ≫ Rrr. Such a reaction cannot be described by simple differential equations, but a Monte Carlo simulation, first generating a random Bernouillian chain and then simulating random attack of the chain by the reactant according to the triad reactivities, allows a good agreement with the experimental results of both the kinetics of a reaction carried out in cyclohexanone solution at 40°C and the evolution of the 13C and 1H NMR spectra of the tertiary carbon atoms, assuming the following parameters: Bernouillian probability for a meso placement in the initial chain: 0.431; relative reactivities of the mm, mr and rm, rr triads: 1, 0.5, and 0., respectively. The agreement is excellent until the reaction is about three‐quarters complete; this shows a limiting level of about 60% substitution. Better agreement can be obtained up to the limit, if a secondary process of steric control by the substituant in a partially substituted mr triad is assumed. Other possibilities for that secondary process are discussed.

Stereoselectivity in substitution reactions of PVC with sodium isooctylthioglycolate and sodium isooctylthiosalicylate

The nucleophilic substitution reactions of a commercial poly(vinylchloride) with sodium isooctylthioglycolate and sodium isooctylthiosalicylate have been studied in solutions in cyclohexanone. The kinetic results show that only a fraction of polymer is capable of reacting even if severe experimental conditions such as high temperature and concentration of nucleophile are used. The reactive parts, as quantitatively estimated according to earlier results, is shown to be higher for sodium isooctylthiosalicylate than for sodium isooctylthioglycolate probably because of the higher nucleophility of the former species despite its higher steric hindrance. 13C-NMR measurements for all the modified samples demonstrate the content of unreacted isotactic and heterotactic triads to be lower as the degree of substitution increases, this effect being more important for triads of the former type during the first stages of the reaction. It is inferred that the stereoselectivity of substitution on PVC is independent of the nucleophile, while both the total reactive parts and the rate of substitution depend on the type of nucleophile. Degrees of substitution of 1–1.3% enhance the thermal stability of the polymer and cause pronounced changes in the u.v.-visible spectrum of the polymer after degradation. Both features are explained on the basis of earlier results with sodium thiophenate. The results indicate a useful pathway for controlled grafting of suitable functions on PVC.

The Kerr effect in cellulose nitrate solutions

Electrical birefringence values have been measured in pulsed fields for cellulose nitrate solutions in cyclohexanone by a compensation method based on sinusoidal modulation of elliptical light polarization. The specific Kerr constants K have been determined for nitrocellulose (NC) samples with nitrogen contents of 11·0, 12·1, 13· and 13·4%. This was done by extrapolation of concentration dependences of K to zero concentration. For the fractionated samples with N contents of 12·1 and 13·4% it was found that the experimental plots of K vs. MW of fractions are described by the theory of Kerr's effect in solutions of vermicular chains. The magnitude and the angle slope of the dipole moments of units relative to contour lengths of the NC chains have been evaluated. Birefringence relaxation has been investigated for NC solutions when the electrical pulse has ended, and the orientational relaxation times τ have been determined. On comparing τ values (obtained by extrapolation to zero concentration) with the intrinsic viscosity and MW of the fractions it is deduced that the NC chains have now acquired kinetic flexibility.

Fast and loose covalent binding of ketones as a molecular mechanism in vertebrate olfactory receptors: Chemical production of selective anosmia

Olfactory receptors undoubtedly have fast rates of association with odorant molecules. If the dissociation rate is also fast, the dissociation constant, K d, will be comparatively large (≥10 -6M). With such fast and loose binding, a receptor will recover function rapidly. If, on the other hand, the dissociation rate is slow, odorant binding will be tight, and the receptor will have slow recorvery. Previous investigators have explored tight binding ( K d≤10 -8M). The present study is the first to probe the possibility of fast and loose binding in the olfactory epithelium of air-breathing vertebrates. Our approach is based on the conjecture that ketones are bound as Schiff bases (just as retinal is bound in visual pigment). As a model system, the Schiff base-forming bacterial enzyme acetoacetate decarboxylase ( AAD) has been studied. Nucleophilic attack (e.g. BH 4- reduction) of reversible AAD-carbonyl complexes produces irreversible binding to the active site in a fraction, φ, of the enzyme molecules. Kinetics are discussed and interpreted using the derived expression φ=1-[ K d/( K d+S 0)] m, where S 0 is the initial concentration of carbonyl substrate and the exponent m is the ratio of the rate constant for attack of the protein-substrate complex to the rate constant for removal of substrate (e.g. by hypothesize attack of the free carbonyl). We hypothesize a similar pathway when the olfactory epithelium of experimental animals is treated with solutions of cyclohexanone or ethyl acetoacetate, in which Schiff base linkages are attacked in vivo by some endogenous nucleophile. We have developed a behavioral assay for olfactory receptor inactivation and report the first example of a chemically produced selective anosmia (odor blindness).

Free‐radical copolymerizations of N‐arylmaleimides. II

AbstractFree‐radical copolymerization of methyl acrylate (MA) with N‐p‐chlorophenylmaleimide (NPCMI) and N‐p‐bromophenylmaleimide (NPBMI) initiated by AIBN in cyclohexanone solution at 75°C was studied. The copolymer composition has been determined from the nitrogen content and NMR spectra of the copolymers. The reactivity ratios have been calculated by ML, FR, KT, and JJ methods. Q and e values of NPCMI and NPBMI have also been calculated by the Alfrey–Price Q‐e scheme.

Photoinduced dark reactions of some cationic dyes

The poor lightfastness of many cationic dyes restricts the range of application which their otherwise attractive spectral properties would predict. Fading mechanisms are varied and complex. The present preliminary account of the photolysis of aerated cyclohexanone solutions of malachite Green, Rosaniline or Rhodamine B for relatively short periods (up to 120 seconds) followed by a longer-term (up to 60 minutes) photoinduced dark bleaching reaction presents a further complication. Some mechanistic possibilities are suggested.

Free Radical Copolymerizations of N-Arylmaleimides

Abstract The free radical copolymerization of methyl acrylate (MA) with N-phenylmaleimide (NPMI) and N-p-tolylmaleimide (NPTMI) at 75° C in cyclohexanone solution initiated by AZBN was studied. The copolymer composition has been calculated from the nitrogen content estimated by the micro-Kjeldahl's method and by NMR spectral studies. The reactivity ratios have been calculated by Mayo and Lewis, Fineman and Ross, Glen and Tüdös, and Joshi and Joshi methods. Q and e values of NPMI and NPTMI were also calculated. Since the reactivity ratios are the measure of distribution of monomer units in a copolymer chain, the values obtained are compared and discussed.