[show abstract][hide abstract] ABSTRACT: This report describes the synthesis of β-hydroxy esters in good yields by reaction of α-aryl substituted ketones and phenylethanal with lithium methyl acetate and derivatives as anionoid reagents. The incomplete substrate conversion is ascribed to the enolate formation of the α-aryl carbonyl compounds, which concurrent reaction is negligibly small with aliphatic carbonyl compounds. The conversion of β-tetralone with lithium methyl acetate has been examined in some detail.
Canadian Journal of Chemistry 02/2011; 62(11):2202-2205. · 0.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: The reaction of sulfur trioxide with benzene, the four halogenobenzenes, and six halogenonaphthalenes in dichloromethane as solvent, and with four chlorinated anthracenes in nitromethane as solvent, has been studied by analysis of the resulting mixture of the sulfo derivatives with 1H NMR. The sulfonation of benzene yields initially benzenesulfonic acid and subsequently the 1,3-disulfonic acid (1,3-S2). The initial sulfonation of the four halogenobenzenes yields ≥ 98% of the 4-S. Their subsequent sulfonation gives the 2,4-S2 and in the case of fluoro- and iodobenzene also the 2,4,6-S3. Monosulfonation of 1-fluoronaphthalene yields only the 4-S, whereas the three other 1-halogenonaphthalenese yield in addition some 5-S. Further sulfonation on any of the four 1-halogenonaphthalene-4-sulfonic acids yields a mixture of the 2,4-S2 and 4,7-S2, and eventually also some 2,4,7-S3, whereas the 1-halogeno-5-sulfonic acids give the corresponding 5,7-S2. Sulfonation of 2-chloro- and 2-bromonaphthalene yields initially 85% 8-S and 15% 4-S, which are subsequently converted into the 6,8-S2 and 4,7-S2, respectively. On reaction with 1.0 mol-equiv. of SO3, 2-chloroanthracene gives the 9-S, and 9-chloroanthracene gives an 18:82 mixture of the 4-S and 10-S. Both 1,5- and 1,8-dichloroanthracene yield initially the 4-S and subsequently the 4,8-S2 and 4,5-S2, respectively.
Canadian Journal of Chemistry 02/2011; 72(9):1966-1971. · 0.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: This study describes a method using 17O nmr to determine the intercarbonyl dihedral angle in a homologous series of seven 1,2-diketones. It is shown that the 17O nmr shifts of the 1,2-diketones are linearly dependent on both the electron density at the oxygen atoms and the n→π* excitation energy of the 1,2-diketo chromophore. Reduction of the overlap in the π system of the 1,2-diketo moiety leads to a gradual upfield shift of the 17O nmr signal, due to the increase in both the π-electron density at the oxygen atoms and the mean transition energy ΔE.
Canadian Journal of Chemistry 02/2011; 65(9):2234-2237. · 0.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: The sulfonation in 98.5% H2SO4 at 25.0 °C of naphthalene-1-sulfonic acid yields 58% 1,5-, 32% 1,6-, and 10% 1,7-disulfonic acids and that of the 2-sulfonic acid 4% 1,3-, 74% 1,6-, 18% 1,7-, and 4% 2,6- + 2,7-disulfonic acids. Further sulfonation of the latter disulfonic acid mixture in 105.2% H2SO4 at 25.0 °C yields 78% 1,3,6- and 12% 1,3,5- + 1,3,7-trisulfonic acids. Reaction of naphthalene-1,5-disulfonic acid with 105.2% H2SO4 at 25 °C yields 5-sulfonaphthalene-1-sulfonic anhydride.Partial rate factors for the sulfonation of naphthalene-1- and -2-sulfonate in highly concentrated aqueous sulfuric acid (where the sulfonating entity is H2S2O7) are reported. They are discussed in terms of the difference in the reactivity of the α- and β-positions of the naphthalene skeleton and the electronic and steric effects of the sulfonate substituent already present.
Canadian Journal of Chemistry 02/2011; 61(7):1453-1455. · 0.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: The sulfonation of benzene-SO2X (X = CH3, OCH3, OH, and Cl) and of 1- and 2-naphthalene-SO2X (X = CH3, OCH3, and Cl) with sulfur trioxide in nitromethane as solvent has been studied. In the benzene series, substitution only occurs at the 3-position irrespective of X; the reaction rates, which are all within the same order of magnitude, are low. Upon sulfonation of the 1-SO2X-substituted naphthalenes, the main sulfonation product (58–80%) is the 5-sulfonic acid (5-S); in addition, 6-S and small amounts of 3-S and 7-S are formed. Also, the formation of the intermolecular sulfonic anhydride of 1-(methylsulfonyl)naphthalene-5-S is observed. The 2-SO2X-substituted naphthalenes all yield the 5-S and 8-S in a ratio of For both the benzene and naphthalene series, insertion of SO3 between the SO2 and X moieties of the chlorosulfonyl and methoxysulfonyl substituents proper takes place. In the benzene series these reactions are fast as compared with the actual ring sulfonation, whereas in the naphthalene series they are, in general, relatively slow. In the naphthalene series the mesomeric directing effect of the SO2X groups is less important than in the benzene series; the "naphthalene α-effect" also plays an important role.
Canadian Journal of Chemistry 02/2011; 71(2):210-215. · 0.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: The mono- and di-sulfonation of the 1,8-alkano- and 1,8:4,5-dialkano-naphthalenes 1–5 with SO3 in dioxane and nitromethane as solvent have been studied and the results compared with those of 1,8-di- (6) and 1,4,5,8-tetramethylnaphthalene (7). The most reactive position of 1,8-ethano- (1), 1,8-propano-naphthalene (2), and 6 is the 4-position. Sulfonation adjacent to the 1,8-ethano bridge can be effected with SO3 in dioxane as reagent, whereas sulfonation ortho to the longer alkano bridges requires the more reactive reagent SO3 in nitromethane. Disulfonation of the1,8:4,5-dialkanonaphthalenes 3–5 leads to the predominant formation of the "noncrossed" (i.e. the 2,7-) disulfonic acid due to the substituent effect of the 2-sulfonic acid group. The isomer distribution data for the sulfonation of the arenes and their monosulfonic acids show that the steric hindrance increases in the order ethano propane ≤ butano and propane < peri dimethyl.
Canadian Journal of Chemistry 02/2011; 63(8):2294-2297. · 0.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: The sulfonation of 1- and 2-naphthol with sulfur trioxide in C2H3NO2 has been studied by using 1H NMR. 1-Naphthol (1) yields, upon reaction with 1.0 mol-equiv of SO3, a mixture of 2- and 4-sulfonic acids (2- and 4-S); upon increasing the reaction temperature, the relative amount of 2-S increases. Upon reaction with 4.0 mol-equiv of SO3, the initially observed products are the hydrogen sulfate 1-O,2,4-S3, and some corresponding sulfonic anhydrides. After prolonged reaction times, some 1-O-4,7-S3, is formed.2-Naphthol (3), upon reaction with 1.0 mol-equiv of SO3, yields a 85: 15 mixture of 1-S and 8-S, whereas upon reaction with 2.0 mol-equiv of SO3, a 8: 14: 78 mixture of the 5-S, 6-S and 8-S are formed. Sulfonation of 3, either by (i) reaction with 1.2 and, subsequently, an additional 2.0 mol-equiv of SO3, or (ii) by direct addition of 4.0 mol-equiv of SO3, yields a mixture of the carbyl sulfates 5-5-S and 5-6-S and the hydrogen sulfate 3-O,6,8-S3, the relative yield depending on the method used.The results are discussed in terms of initial formation of the corresponding naphthyl hydrogen sulfates and on the basis of a comparison with the reactions of 1- and 2-naphthyl methanesulfonates, the chosen model compounds for the hydrogen sulfates, with SO3.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 112(3):210 - 215.
[show abstract][hide abstract] ABSTRACT: The reaction of neat toluene with a number of different sulfonation reagents at 25° has been studied. With sulfur trioxide vapour as reagent, the reaction leads to monosulfonation only. The o/(o + m + p) ratio varies with the degree of toluene conversion, the limiting values at zero and high conversion being 0.34 ± 0.03 and 0.11 ± 0.01, respectively. The former value is ascribed to the sulfonation of toluene with sulfur trioxide, the latter to sulfonation in the acid phase with toluenepyrosulfonic acid as the sulfonating entity.The heterogeneous reaction of toluene with a deficient amount of a matured mixture of methanesulfonic acid and sulfur trioxide - i.e. with a methanepyrosulfonic acid reagent — leads to monosulfonation only. The o/(o + m + p) ratio varies from 0.15 ± 0.01 at zero toluene and zero time conversion to 0.11 ± 0.01 at high toluene conversion. The former value is ascribed to sulfonation in the acid phase of dissolved toluene by methanepyrosylfonic acid, the latter to that by both toluene- and methane-pyrosulfonic acids.Heterogeneous sulfonation with a deficient amount of fuming sulfuric acid takes place mainly ( ∼97 %) in the acid phase. Sulfonation in the toluene phase leads to monosulfonic acids only with 41 ± 2 % of ortho-substitution. Sulfonation in the sulfuric acid phase yields monosulfonic acids and, at the higher sulfuric acid concentrations, also toluene-2,4-disulfonic acid. The degree of ortho-substitution for sulfonation in the acid phase at 25° changes from 48.5 to 40 % on varying the acid concentration from 100.0 to 106.4% H2SO4.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 90(2):193 - 206.
[show abstract][hide abstract] ABSTRACT: The photochemistry of (E)-α- and (E)-β-damascone has been studied. Upon triplet-sensitized irradiation, both compounds exclusively undergo (E)-(Z) isomerization. (E)-β-damascone, upon direct irradiation with λ 254, 300 or 350 nm in non-alcoholic solvents, exhibits only (E)-(Z) isomerization. However, in an alcoholic solvent, direct irradiation induces cyclization and subsequent solvent incorporation, with formation of exo-8-alkoxy-1,5,5-endo-9-tetramethyl-cis-bicyclo[4.3.0]nonan-7-one (12).(E)-α-damascone, upon direct irradiation, exhibits α-cleavage with subsequent formation of the 1,3-acyl shift product, and equal amounts of the dimerization products of the allylic radical, viz.9 and 10. The 1,3-acyl shift product again undergoes photo-α-cleavage and the only products, upon prolonged irradiation, are the bicyclohexenyls 9 and 10.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 102(6):307 - 311.
[show abstract][hide abstract] ABSTRACT: The photochemistry of the diphenyl β,-enones 2 and 3 and the methyl- and phenyl-substituted -phenyl ketones 4-9 has been studied, using mainly benzene as solvent. Irradiation of 2 with λ 300 nm leads to the 1,3-acyl shift (1,3-AS) product 17, relatively small amounts of the decarbonylation products 15 and 16, and the photo-oxidation products benzophenone (18) and the ,β-unsaturated aldehyde 19. Direct irradiation of the 1,3-AS product 17 yields 15, 16, 18 and 19, but no 2.Direct irradiation of 3 with λ 350 nm leads mainly to the formation of 1,3-AS products (E)- and (Z)-22, the decarbonylation products (E)- and (Z)-20 and 21 and, in addition, a small amount of the cis-di-π-methane isomer 23.Direct irradiation of the substituted -phenyl ketones 4, 5, 8 and 9 with 300 nm leads predominantly to the formation of the radical coupling products 2,3-butanedione and 24-27, respectively, whereas 6 and 7 yield 1,2-diphenyl-1,2-ethanedione and the respective 24 and 25. The acetone-sensitized irradiation of 4 leads to 4-phenyl-2-butanone (33) in addition to 2,3-butanedione and 1,2-diphenylethane (24).
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 107(12):676 - 683.
[show abstract][hide abstract] ABSTRACT: Cyclopropanecarbaldehyde has been photolysed in the gas-phase with light in the 313 nm region at temperatures from 50 to 190 °C and at various aldehyde pressures. The most important gaseous reaction products are carbon monoxide, propene and cyclopropane. The quantum yield of propene, which is practically independent of temperature, decreases with increasing aldehyde pressure. The quantum yield of cyclopropane increases with both temperature and aldehyde pressure but decreases with increasing intensity of the absorbed light.It is proposed that propene is formed by intramolecular decomposition of singlet excited cyclopropanecarbaldehyde, whereas cyclopropane ultimately results from a radical decomposition of triplet cyclopropanecarbaldehyde.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 87(1):73 - 85.
[show abstract][hide abstract] ABSTRACT: A series of α,α,ω,ω-tetramethyl-1,2-cycloalkanediones, with a ring size varying between 4 and 8 C atoms (la-e), together with 2,2,5,5-tetramethyl-3,4-hexanedione (2a), have been irradiated both in 2-propanol and in benzene in order to study the influence of the diketo conformation on the photochemical behaviour of 1,2-diketones. Irradiation of lb-d in 2-propanol leads exclusively to photoreduction with formation of the corresponding acyloins via intermolecular H abstraction, whereas le and 2 yield predominantly the 2-hydroxycyclobutanone product via intramolecular H abstraction. The irradiations of la-e in benzene lead to different products for the six homologous cyclic 1,2-diketones. Mechanisms for the formation of the various products are proposed. It is concluded that the 1,2-diketones with Φ (ground state) <90° and >90° react, upon excitation, from a conformation having a planar cisoid and transoid diketo geometry, respectively.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 102(3):173 - 181.
[show abstract][hide abstract] ABSTRACT: Reactions of methylenecycloalkanes 1a-4a and cycloalkylidenecycloalkanes 11a–14a with sulfur trioxide were studied in the temperature range −60 to 25°C using dichloromethane as solvent and 1.5 mol equiv. of dioxane relative to the amount of SO3 as reactivity moderator. Methylenecyclooctane (1a), methylenecyclohexane (2a) and methylenecylopentane (3a) react with SO3 just like simple branched alkenes yielding quantitatively the corresponding β-alkenesulfonic acids 1d-3d. Reaction of methylenecyclobutane (4a) with 1.0 equiv. of SO3 at −60°C yields the β-sultone 4b, which upon raising the temperature to 0°C, rearranges into γ-sultone 6 and subsequently, slowly into δ-sultone 9. Sulfonation of the cycloalkylidenecycloalkanes 11a-13a with 1.0 equiv. of SO3 at −60°C leads to quantitative formation of the spiro-β-sultones 11b-13b, respectively. After raising the temperature, these β-sultones are converted into the corresponding β-alkenesulfonic acids 11d-13d, which are common reaction products in sulfonation of tetraalkylethenes.Sulfonation of cyclopropylidenecyclopropane (14a) with SO3 at −60°C proceeds with rearrangement of one of the cyclopropyl groups to give quantitatively the spirocyclopropane-γ-sultone 15. Mechanisms for the formation of the various products are discussed.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 112(7‐8):457 - 461.
[show abstract][hide abstract] ABSTRACT: The kinetic isotope effect of hydrogen in the nitration of anthracene with nitronium tetrafluoroborate has been determined, using anthracene-9-d as substrate. In sulfolane as solvent at 30° and in acetonitrile at 0°, kH/kD was found to be equal to 2.6 ± 0.3 and 6.1 ± 0.6, respectively. The kinetic isotope effect of hydrogen in the nitration of naphthalene in these two solvents under similar reaction conditions, using naphthalene-1,4-d2 as substrate, were found to be 1.15 ± 0.05 and 1.08 ± 0.05, respectively.UV spectral evidence was obtained that the nitration of anthracene with nitronium tetrafluoroborate in sulfolane as solvent proceeds via an intermediate which is suggested to be the 9-nitro-9-anthracenonium ion. This intermediate is formed directly on mixing the reagents. The proton transfer from this intermediate with formation of 9-nitroanthracene is a relatively slow process.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 86(4):371 - 380.
[show abstract][hide abstract] ABSTRACT: The solubility of benzene and toluene in aqueous sulfuric acid > 75 wt-% has been determined at 5, 25 and 45°.Molar heats of solution have been calculated. The benzene to toluene activity coefficient ratio is slightly greater than unity. The relatively large difference in activation entropy for sulfonation of the para-position in toluene and a single position in benzene1 is therefore attributed mainly to differences in solvation of the transition states.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 84(5):545 - 550.
[show abstract][hide abstract] ABSTRACT: The isomer distribution in the homogeneous monosulphonation of toluene in 77.6-98.8 wt- % aqueous sulphuric acid has been determined at various temperatures between 5 and 65°. Sulphone formation and disulphonation are negligible. The isomer distribution is independent of toluene conversion. The degree of meta-substitution is low under all conditions. At 25.0° the ratio of o- to p-toluene-sulphonic acid changes from 0.276 to 1.08 on varying the concentration of sulphuric acid from 77.6 to 98.8 wt-%; the meta-isomer shows only a small increase over this acid range. The decrease in the partial rate factor ratio, fp/fm, with increasing sulphuric acid concentration results mainly from an increase in the activation enthalpy difference between para- and meta-substitution. This decrease in fp/fm, is taken as an indication of increasing reactivity of the sulphonating entity.The entropy of activation is greater for para-substitution than for ortho-substitution. On varying the sulphuric acid concentration from 77.6 to 95.8 wt-%, the entropy difference decreases from 8.8 ± 0.2 to 4.8 ± 0.7 cal · degree-1 · mole-1 probably because the solvation of the transition state leading to ortho-substitution decreases with increasing acid concentration. The difference in activation enthalpy between para- and ortho-substitution is 1.3 ± 0.2 kcal · mole-1, whatever the acid concentration. This enthalpy difference is explained by an intramolecular hyperconjugative proximity effect in the transition state leading to ortho-substitution.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 82(7):659 - 670.
[show abstract][hide abstract] ABSTRACT: The (E)- and (Z)-isomers of the 3,3,n,n-tetramethyl-2-(methoxyimino)-1-cycloalkanones (n = 5 to 7) (3a-c) and their acyclic analogue (Z)-4-(methoxyimino)-2,2,5,5-tetramethyl-3-hexanone [(Z)-4] have been irradiated at λ 254 nm in acetonitrile as solvent in order to study the influence of ring size on product formation. The dependence of product composition on irradiation time revealed that the (E)-isomers of 3a-c undergo both E-Z isomerization and photodecomposition, whereas the (Z)-isomers undergo only Z-E isomerization. The primary step in photodecomposition is homolysis of the NO bond. The observed products result from the various possible reactions of initially formed methoxy and cyclic iminyl radicals 17, cyanoacyl radicals 18 formed by ring opening of 17, cyanoalkyl radicals 19 formed from 18 by decarbonylation and cyclopentaniminyl radical 20b, formed by cyclization of the 5-cyano-2-hexyl radical 19b. Mechanisms for the formation of the various products are proposed and the relative importance of the various steps is discussed, also in relation to the results obtained using carbon tetrachloride as radical scavenger.Irradiation of (Z)-4 at λ 254 nm leads to decomposition with formation of 2,2-dimethylpropanenitrile, methanol, isobutane and isobutene.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 109(10):491 - 501.
[show abstract][hide abstract] ABSTRACT: With the objective of understanding the photodissociation of cyclic s-cisoid α-oxo oxime ethers upon irradiation at λ 254 nm, an ab-initio study has been performed using s-cis-ethanedial monooxime as model compound. In accordance with previously presented experimental observations, the calculations demonstrated (i) that the initial step in the photodissociation is NO homolysis and (ii) that NO scission takes place with the (E), but not with the (Z) isomer, due to the presence of a relatively low-lying doubly excited (nπ*)(nπ*) state with the (Z) isomer, causing this isomer to decay via Z-E isomerization.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 109(10):502 - 508.
[show abstract][hide abstract] ABSTRACT: The degree of ortho-substitution in the sulfonation of toluene, ethylbenzene and isopropylbenzene with sulfuric acid varying in concentration from 80.6 to 98.5% H2SO4 at 25° was determined. For a given sulfuric acid concentration the ratio of ortho- to (para- + meta-) substitution decreases with increasing size of the alkyl group, whereas for a given alkyl group this ratio decreases with decreasing sulfuric acid concentration.Partial rate factors for the homogeneous sulfonation of toluene, ethylbenzene, isopropylbenzene and t-butylbenzene in 86.3% sulfuric acid at 25° were calculated. The partial rate factors for ortho-substitution decrease with increasing size of the alkyl group, while those for para-substitution follow the Baker-Nathan order.Introduction of a sulfonic acid group ortho to the alkyl group of an alkylbenzene can be effected with weak oleum (∼ 16%) as reagent under conditions of disulfonation with toluene, ethylbenzene and isopropylbenzene, but not with t-butylbenzene.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 86(8):873 - 878.
[show abstract][hide abstract] ABSTRACT: The dependence of the sulfonation rates and isomer distributions of several aromatic compounds on the sulfuric acid concentration is explained in terms of two reaction mechanisms. One involves H2S2O7 as the sulfonating entity and predominates at high sulfuric acid concentrations; the other, with H3SO4+ as the sulfonating entity, predominates at lower acid concentrations. The latter mechanism is more selective than the former.
Recueil des Travaux Chimiques des Pays-Bas. 09/2010; 87(1):24 - 32.