Microstructures of 2,5-dialkyl benzene sulfonate micelles studied using H NMR

Micellization of a series of newly synthesized dialkyl benzene sulfonates was studied using proton chemical shift changes, spin-lattice and spin-spin relaxation NMR spectroscopy, and two-dimensional nuclear Overhauser enhancement spectroscopy (2D NOESY). The o-substituted chains are normal alkyl chains with varying lengths, and the m-substituted ones are branched alkyl chains. The results showed that the longer the o-substituted normal alkyl chain, the more the methylene groups participated in the formation of the rigid surface layers of the hydrophobic micellar cores. Consequently, the larger was the area per molecule adsorbed on the interface between oil and water at saturation. The branched m-substituted alkyl chains of the dialkyl benzene sulfonates were less tightly packed than the o-substituted normal alkyl chains in the hydrophobic micellar cores. The shorter the m-substituted branched alkyl chains, the looser they were packed in the hydrophobic micellar cores. The relative arrangement of the surfactant molecules in the micelles was elucidated.     

Physicochemical Characterization of Two Polysulfon-Amides in Dilute Solution

Summary: As one class of high temperature resistant aromatic polymers, polysulfonamides (PSA) are widely used in industry, physicochemical properties and conformation in solution have not been disclosed yet. In this work, the dilute solution behaviour of poly(m-diphenylsulphone terephthal amide) (m-PSA) was investigated by laser light scattering (LLS) and viscometry. The results showed that the m-PSA exists as single chains both in dimethylsulfoxide (DMSO) and dimethylformamide (DMF). The value of radius of gyration to hydrodynamic radius (s/R_h) indicats that the m-PSA has a random coil conformation in solution. Both the persistence length a and the characteristic ratio C_∞ indicate that the m-PSA chain is flexible in solution. The Mark-Houwink equation of m-PSA in DMSO was determined as [η] = 1.62 × 10⁻⁵M, and the exponent of 0.87 supports the assumption that m-PSA forms random coils in DMSO-solution at 25 °C. It was found that the flexibility of the PSA was affected when 4,4'-diphenylsulphone terephthalamide monomer was incorporated in backbone. The PSA random copolymer (r-PSA) with a comonomer ratio of 3:1 (4,4′-diaminodiphenyl- sulfone to 3,3′-diaminodiphenylsulfone) also had a random coil conformation in DMF; the rigidity increased, while the mobility of the chain was maintained.     

Synthesis of new 3-(phenoxyphenyl)sydnones marija Šindler-kulyk

The title compounds were prepared by dehydrocyclization of corresponding substituted N-nitrosoglycines obtained from isomeric o-, m- and p-aminodiphenyl ether with ethyl bromoacetate and subsequent nitrosation of the intermediate N-arylsubstituted glycines.     

Surface tensions and surface heats of mixing of mixtures containing bromobenzene at 293.15 and 303.15 K

Surface tensions of mixtures of bromobenzene with cyclohexane, benzene,o-, m-, andp-xylene have been determined by the capillary rise method at 293.15 and 303.15 K. The data have been used to check the various theories of surface tension of liquid mixtures. The surface heats of mixing have been computed at 293.15 K as a function of composition.

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Oberflächenspannungen und Oberflächen-Mischungswärmen von Mischungen mit Brombenzol als eine Komponente, bei 293,15 und 303,15 K

Zusammenfassung Die Oberflächenspannungen von Mischungen von Brombenzol mit Cyclohexan, Benzol undo-, m- undp-Xylol wurden mit der Kapillarmethode bei 293,15 und 303,15 K bestimmt. Die Daten wurden zur Überprüfung verschiedener Theorien der Oberflächenspannung herangezogen. Die Oberflächen-Mischungswärmen wurden für 293,15 K berechnet.

     

Applicability of Silicone Membrane Passive Samplers for Monitoring of Indoor Air Quality

ABSTRACT

A series of experiments were conducted to investigate the permeability of membranes made of silicone foil with respect to selected volatile organic compounds such as butanol, benzene, toluene, butyl acetate, ethylbenzene, m- xylene, styrene, m- dichlorobenzene. On the basis of model experiments the calibration constants k for 18 passive samplers were determined (with respect to each compound present in the gaseous standard mixture).

The obtained calibration constants found are characterised by good precision (except for butanol, relative standard deviation are not greater than 9%). The comparison of the calibration constants for the samplers with silicone membrane of 50 μm thick with those obtained for samplers with polyethylene membrane of 15.5 μm shows that silicone membrane samplers will give higher enrichment factors for the compounds studied.     

Synthesis of dithia- and tetrathiacyclophanes incorporating isoxazole units

The reaction of 5-bromomethyl-3-(p-bromomethylphenyl)isoxazole with o-, m-, and p-bis(mercap-tomethyl)benzenes gave the corresponding dithia- and/or tetrathiaisoxazolophanes, whose relative yields strongly depended upon the nature of the mercaptomethyl compound. The above isoxazole dibromide reacted with the bis(mercaptomethyl)isoxazole to afford a mixture of two isomeric dithiaisoxazolophanes.     

Synthesis of New Functionalized Heterocyclic [4,3,3] Propellanes via Three‐component Reaction Based on Ninhydrin–Phenol Adducts

Three‐component reaction between ninhydrin–phenol adducts, dialkyl acetylenedicarboxylates, and triphenylphosphine was investigated. Utilizing this protocol, dialkyl 10‐oxo‐10H‐4b,9b‐(epoxyethanooxy)indeno[1,2‐b]benzofuran‐12,13‐dicarboxylates as functionalized heterocyclic [4,3,3] propellanes was synthesized in 6‐endo‐trig cyclization mode. 8‐hydroxyquinoline showed serendipitous reactivity and produced para substituted adduct in the reaction with ninhydrin in acetic acid media and hence produced dialkyl 8a‐(4‐(alkoxycarbonyl)‐2‐oxo‐2H‐pyrano[3,2‐h]quinolin‐6‐yl)‐8‐oxo‐8,8a‐dihydro‐2H‐indeno[2,1‐b]furan‐2,3‐dicarboxylate in the reaction with dialkyl acetylenedicarboxylates and PPh₃.     

Mass spectrometry in structural and stereochemical problems—CXCIX Contrasting fragmentations of singly- and doubly-charged o-, m- and p-hydroxyalkylphenones and their trimethylsilyl ethers

High resolution mass spectrometry, metastable defocusing and deuterium labeling of trimethylsilyl (TMS) ethers have been used to study the electron-impact induced fragmentations of o-, m- and p-hydroxyalkylphenones and their TMS ether derivatives. These derivatives have proven useful in contrasting the fragmentation patterns of singly- and doubly-charged ions because of the competing fragmentations: α-cleavage and a McLafferty rearrangement from the ketone moiety and methyl cleavage from the TMS group. A proximity effect was responsible for a markedly increased methyl radical loss from the o-TMS ether. This fragmentation was minor with the m- and p-isomers. Significantly intense doubly-charged ions were formed from ketonic cleavage and by the loss of a TMS methyl radical. The sequence of fragmentation depended on the size of the alkyl group attached to the ketone carbonyl. There was no evidence found for a McLafferty rearrangement occurring from the doubly-charged molecular ion of the TMS ethers of the hydroxyalkylphenones but the rearrangement occurred from the doubly-charge molecular ion of bis-3-(1-oxopentyl)-4-hydroxy-phenyl-methane and, of course, from the singly charged [M]^+. The bis-p-hydroxyphenylmethane derivatives were studied in an effort to increase the intensity of the doubly-charged ions as it was expected that the charges would be separated by a longer distance.     

Regioselective Reaction of N1-Benzyl-N2-(4-nitrophenyl)ethanediamide and Acetylenic Esters

The regioselective reaction of N¹-benzyl-N²-(4-nitrophenyl)ethanediamide with dialkyl acetylenedicarboxylates or alkyl propiolates in the presence of triphenylphosphine leads to dialkyl 4-benzylamino-1-(4-nitrophenyl)-5-oxo-2,5-dihydro-1H-pyrrole-2,3-dicarboxylates or alkyl 4-benzylamino-1-(4-nitrophenyl)-2-oxo-5-pyrrolidinecarboxylates in good yields.     

Chemoselective and Regiospecific Synthesis of Iminospiro‐γ‐lactones from Maleic Anhydride or Citraconic Anhydride and Alkyl Isocyanides with Dialkyl Acetylenedicarboxylates

Isocyanides, dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates), and anhydrides such as maleic anhydride (=furan‐2,3‐dione) or citraconic anhydride (=3‐methylfuran‐2,3‐dione) react in one pot to afford novel iminospiro‐γ‐lactones in fairly good yields at room temperature (Schemes 1 and 3).     

One-pot, three-component reaction of isocyanides, dialkyl acetylenedicarboxylates, and non-cyclic anhydrides: synthesis of 2,5-diaminofuran derivatives and dialkyl (E)-2-[(N-acyl-N-alkylamino)carbonyl]-2-butenedioates

Abstract  

Isocyanides, dialkyl acetylenedicarboxylates, and non-cyclic anhydrides, for example acetic anhydride or benzoic anhydride, react in one-pot to afford 2,5-diaminofuran derivatives and dialkyl (E)-2-[(N-acyl-N-alkylamino)carbonyl]-2-butenedioates in fairly good yields at room temperature.     

HIGHLY STEREOSELECTIVE SYNTHESIS OF DIALKYL 2-ALKYLIDENE GLUTARATES

Nucleophelic substitution of dialkyl (E)-2-bromomethylene glutarates 2 by magnesium dialkyl cuprates generated in situ provided a regio and highly stereoselective methodology for the synthesis of dialkyl 2-alkylidene glutarates 3 in good yields.     

Unexpected Formation of Thioglycolurils Precursors

Unexpectedly, nitrosation of 5,7‐dialkyl‐3‐thioxoperhydroimidazo[4,5‐e]‐1,2,4‐triazine‐6‐ones(thiones) with sodium nitrite in glacial AcOH led to 3,3′‐bis(5,7‐dialkyl‐1‐nitroso‐6‐oxo(thioxo)‐1,4,4a,5,7,7a‐hexahydroimidazo[4,5‐e]‐1,2,4‐triazinyl)disulfides that decomposed spontaneously into 1,3‐dialkyl‐5‐thioxohexahydroimidazo[4,5‐d]imidazol‐2(1H)‐ones(thiones) in DMSO‐d₆ in the presence of water.     

Dipotassium Hydrogen Phosphate Powder-Catalyzed Stereoselective Synthesis of N-Vinyl Pyrazoles in Solvent-Free Conditions

Protonation of the highly reactive 1:1 intermediates, which are produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by 3,5-dimethylpyrazol leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce dialkyl 2-(3,5-dimethyl1H-pyrazol-1-yl)-3-(triphenylphosphoranylidene)butanedioates. Dipotassium hydrogen phosphate powder was found to catalyze the stereoselective conversion of dialkyl 2-(3,5-dimethyl-1H-pyrazol-1-yl)-3-(triphenylphosphoranylidene) butanedioates to dialkyl 2-(3,5-dimethyl-1H-pyrazol-1-yl)-2-butenedioates in solvent-free conditions under microwave (0.6 KW, 3 min) and thermal (90°C, 60 min) conditions.     

Synthesis and spectral properties of 2,3-dihydro-4-(paramethylphenyl)-7-[(o,m-, and p-substituted)phenoxy]-1H-1,5-benzodiazepine-2-thiones

A series of twelve new 2,3-dihydro-4-(para-methylphenyl)-7-[(o-, m-, and p-substituted)phenoxy]-1H-1,5-benzodiazepine-2-thiones. which have potentially useful pharmacological properties, has been synthesized by condensing the 3,3-dimercapto-1-(p-methylphenyl)-2-propen-1-one with 3,4-diaminophenyl-R-phenyl ethers. The structure of all products was corroborated by ir; ¹H-nmr; ¹³C-nmr and ms.     

Synthesis of fluorine-containing quinoline-2,3-dicarboxylates from products of vicarious nucleophilic substitution of hydrogen in 3-fluoronitroarenes

The reactions of 3-fluoro-4-R-6-phenylsulfonylmethylnitrobenzenes with dimethyl fumarate or diethyl maleate in acetonitrile in the presence of an excess of K₂CO³ and a catalytic amount of 18-crown-6 afforded mixtures of dialkyl 6-R-7-fluoro- and dialkyl 6-R-7-phenylsulfonylquinoline-2,3-carboxylate N-oxides, as well as dialkyl 6-R-7-fiuoro- quinoline-2,3-carboxylates (alkyl is methyl or ethyl), which were resolved by column chromatography and identified by ¹H NMR spectroscopy and X-ray diffraction.     

Synthesis and physicochemical studies on Ni(II) complex of 2-hydroxy-acetophenonethiosemicarbazone and its square-planar adducts with nitrogen donors

NiL₂X₂ complex and its adducts of the type NiL (base), where L is a 2-hydroxy-acetophenonethiosemicarbazone, X=C1 and base (ammonia, pyridine, aniline,o-, m-, p-toluidine and water) have been synthesized and characterised by analysis, magnetic moments, electronic and infrared spectra.     

Synthesis of New Substituted Thioglycolurils via a Tandem Hydrazone Formation‐ Ring Contraction Reaction

A series of new (E)‐1,3‐dialkyl‐4‐((hetarylmethylidene)amino)‐5‐thioxohexahydroimidazo[4,5‐d]imidazole‐2(1H)‐ones (thioglycolurils) was synthesized via tandem hydrazone formation—ring contraction reaction of 5,7‐dialkyl‐3‐thioxoperhydroimidazo[4,5‐e]‐1,2,4‐triazin‐6‐ones with heteroaromatic aldehydes.     

A Facile One‐Pot Synthesis of Functionalized 1,5‐Dihydro‐2H‐[1]benzopyrano[2,3‐b]pyridin‐5‐ones

The highly reactive 1 : 1 intermediate generated in the reaction between dialkyl acetylenedicarboxylate (=but‐2‐ynedioic acid dialkyl ester) 4 and triphenylphosphine was trapped by 2‐amino‐4‐oxo‐4H‐1‐benzopyran‐3‐carboxaldehydes 5 to yield highly functionalized dialkyl‐1,5‐dihydro‐5‐oxo‐1‐phenyl‐2H‐[1]benzopyrano[2,3‐b]pyridine‐2,3‐dicarboxylates in high yield.     

Reactions of N,N-(dialkyl)arylthioacetamides with dialkyl acetylenedicarboxylates

2-(Alkoxycarbonylmethylidene)-4-aryl-5-(dialkylamino)thiophen-3(2H)-ones were synthesized by condensation of N,N-(dialkyl)arylthioacetamides with dialkyl acetylenedicarboxylates. Intermediate substituted vinylic sulfides were isolated. When heated or in the presence of an acid or a base, they undergo cyclization into thiophenes.