Alkyl Methyl Research Articles

Antimicrobial films obtained from latex particles functionalized with quaternized block copolymers

New amphiphilic block copolymers with antimicrobial properties were obtained by atom transfer radical polymerization (ATRP) and copper catalyzed cycloaddition following two approaches, a simultaneous strategy or a two-step synthesis, which were proven to be very effective methods. These copolymers were subsequently quaternized using two alkyl chains, methyl and butyl, to amplify their antimicrobial properties and to investigate the effect of alkyl length. Antimicrobial experiments in solution were performed with three types of bacteria, two gram-positive and one gram-negative, and a fungus. Those copolymers quaternized with methyl iodide showed better selectivities on gram-positive bacteria, Staphylococcus aureus and Staphylococcus epidermidis, against red blood cells, demonstrating the importance of the quaternizing agent chosen. Once the solution studies were performed, we prepared poly(butyl methacrylate) latex particles functionalized with the antimicrobial copolymers by emulsion polymerization of butyl methacrylate using such copolymers as surfactants. The characterization by various techniques served to test their effectiveness as surfactants. Finally, films were prepared from these emulsions, and their antimicrobial activity was studied against the gram-positive bacteria. The results indicate that the antimicrobial efficiency of the films depends not only on the copolymer activity but also on other factors such as the surface segregation of the antimicrobial agent to the interface.

Rapid Access to Polyfunctionalized 3,4‐Dihydroquinazolinones through a Sequential N‐Acyliminium Ion Mannich Reaction Cascade

AbstractA microwave‐promoted one‐pot, three‐component sequential cyclization‐Mannich reaction of unactivated ketones, o‐formyl carbamates and primary amines has been developed. Cyclic N‐acyliminium ions are generated in situ from the carbamate and amine starting materials. This metal‐free cascade protocol provides rapid access to structurally diverse 3,4‐dihydroquinazolinones in good to excellent yields with high regioselectivity for the terminal methyl group, in the case of unsymmetrical methyl alkyl ketones. Key features of the developed protocol include its operational simplicity, ease of product purification, and wide functional group tolerance.

Aldol Reactions of Ketone Donors with Aryl Trifluoromethyl Ketone Acceptors Catalyzed by 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU) for Concise Access to Aryl‐ and Trifluoromethyl‐ Substituted Tertiary Alcohols

AbstractMolecules bearing aryl‐ and trifluoromethyl‐substituted tertiary alcohol moieties are important as bioactive molecules, enantiomer‐discriminating reagents, and their synthons and building blocks. To concisely synthesize these molecules, we have developed aldol reactions of ketone donors with aryl trifluoromethyl ketone acceptors catalyzed by 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU). The reactions were relatively fast, and the products were obtained in good to high yields under mild conditions. The CC bonds of the aldol reactions formed in perfect regioselectivities at the methyl group of the alkyl methyl ketones, at the γ‐position of the β‐keto esters, and at the methyl group of the β‐methyl‐substituted cyclic enones. For the aldol products from the reactions of β‐keto esters, the enantiomerically pure forms were obtained by resolution of the enamines of the aldol products with a homochiral amine. Our methods provide a concise, fast access to molecules with tetrasubstituted carbon centers with trifluoromethyl‐substituted alcohol moieties.magnified image

Dimethyl sulfite a potential agent for methylation

The synthesis of methylated ether compounds is an important challenge. A pathway for the synthesis of methyl ethers was investigated using dimethyl sulfite (DMSi). Methylation of 1-octanol was carried out in liquid phase upon different heterogeneous organic and inorganic catalysts at 130 °C. Aluminium oxide gave the best result with high conversion and moderate selectivity for methyl 1-octyl ether. Reactions in gas phase at higher temperatures (200 °C) were also performed. Methyl 1-octyl ether was obtained in a very high level of selectivity up to 98%. Primary and secondary ethers from unsymmetrical alkyl methyl sulfite were also performed by SO2 extrusion.

The Effect of Alkyl Substituents on Actinide and Lanthanide Extraction by Diglycolamide Compounds

The effect of the alkyl substituents on amidic N atoms in diglycolamide (DGA) compounds on solvent extraction has been investigated. The solubility in water and n-dodecane, lanthanide loading capacity, and distribution ratios (D) of lanthanides and actinides for various DGA compounds are reported. DGA derivatives with short alkyl chains, for example, methyl and ethyl groups, are very water soluble, while DGA derivatives with long alkyl chains, for example, octyl (TODGA), decyl (TDDGA), dodecyl (TDdDGA), and 2-ethylhexyl (TEHDGA) group are moderately soluble in n-dodecane. DGA derivatives with phenyl substituents have very low solubility in both aqueous and organic solvents, which suggests that these compounds will not be suitable for solvent extraction applications in the HNO3/n-dodecane systems. The lanthanide loading capacities of DGA extractants correlate with their alkyl chain lengths according to the following order: TDdDGA > TDDGA > TODGA > TEHDGA. The branched-alkyl-chain DGA derivative (TEHDGA) exhibits both lower D and loading capacity than TODGA. The results of masking-effect and solubility tests indicate that TEDGA is the best actinide masking agent among the water-soluble DGA derivatives tested. Actinide and lanthanide extractions using ten DGA compounds in six diluents (nitrobenzene, 1,2-dichloroethane, 1-octanol, chloroform, toluene, and n-dodecane) are also reported; it was observed that lipophilic DGA derivatives with shorter alkyl chains show higher D values.

Synthesis and Herbicidal Activities of Sodium Methyl(α-(Substituted Phenoxyacetoxy)Alkyl)Phosphinates

GRAPHICAL ABSTRACT

Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment

Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a method for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We also demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%.

ChemInform Abstract: Copper‐Catalyzed Regioselective Synthesis of Furan via Tandem Cycloaddition of Ketone with an Unsaturated Carboxylic Acid under Air.

AbstractThe operationally simple preparation of 2,3,5‐trisubstituted furans succeeds upon the reaction of aryl alkyl ketones, 2‐phenylacetophenone, and various cyclic ketones with cinnamic acid derivatives, but fails using alkyl methyl ketones or crotonic acid.

Molecular Orientation Analysis of Alkyl Methylene Groups from Quantitative Coherent Anti-Stokes Raman Scattering Spectroscopy.

Quantitative data analysis in coherent anti-Stokes Raman scattering (CARS) spectroscopy is important for extracting molecular structural information. We developed a method to derive molecular tilt angle with respect to the surface normal based on quantitative CARS spectral analysis. We showed that the tilt angle of methylene alkyl chains on a surface can be directly obtained from the CH2 symmetric/asymmetric peak ratio in a CARS spectrum. The lipid alkyl chain tilt angle from a lipid monolayer was measured to be ∼0° and was verified by sum frequency generation spectroscopy, which probes the orientations of the lipid methyl end groups. The tilt angle of a silane monolayer alkyl chain was derived to be ∼35°, which agrees with the theoretical prediction. This method is submonolayer sensitive and can also be used to interpret polarization-dependent signals in CARS microscopy. It can be applied to elucidate detailed molecular structure from CARS spectroscopic and microscopic measurements.

ChemInform Abstract: A Highly Enantioselective and Regioselective Organocatalytic Direct Mannich Reaction of Methyl Alkyl Ketones with Cyclic Imines Benzo[e][1,2,3]oxathiazine 2,2‐Dioxides.

AbstractThe direct Mannich reaction of the cyclic title imines with acetone or alkyl methyl ketones generates optically active N‐heterocycles bearing a sulfonamide functionality with high enantioselectivities and high yields.

2,1-Benzothiazine 2,2-Dioxides. 9*. Alkylation of Methyl 4-Hydroxy-1-Methyl-2,2-Dioxo-1Н-2λ6,1-Benzothiazine-3-Carboxylate with Ethyl Iodide

The alkylation of methyl 4-hydroxy-1-methyl-2,2-dioxo-1Н-2λ6,1-benzothiazine-3-carboxylate in DMSO or acetone with ethyl iodide at 25°С gave a mixture of 3-ethyl- and 4-ethoxy-substituted derivatives, in complete agreement with quantum-chemical calculations. The ratio of С- and О-alkylation products changed depending on the alkali metal carbonate used as a base. The reaction practically did not proceed in anhydrous THF or water due to the low nucleophilicity of the anion.

ChemInform Abstract: A Concise Account of the Chemistry of Valuable Alkyl(methyl)maleic Anhydrides

AbstractReview: [90 refs.

Kinetic Evaluation of Spin Trapping Rate Constants of New CYPMPO-type Spin Traps for Superoxide and Other Free Radicals

Abstract CYPMPO (5-(2,2-dimethyl-1,3-propoxyl cyclophosphoryl)-5-methyl-1-pyrroline N-oxide) is a phosphorus containing spin trap that has been useful in aqueous media. Using a kinetic ESR spin trapping technique, we evaluated free radical trapping rate constants of two newly synthesized CYPMPO-type spin traps, including 2,2-dibutyl-substituted CYPMPO (DBCYP) and 5-phenyl-substituted CYPMPO (PhCYP). We investigated the spin trapping of five free radical species, i. e., superoxide, hydroxyl radical, alkoxyl radical, alkyl peroxyl radical and methyl radical. Other than superoxide, spin trapping rate constants of DBCYP and PhCYP are comparable to CYPMPO, ranging from 43.9% to 101% of CYPMPO's corresponding rate constants. However, PhCYP's spin-trapping rate constant against superoxide was 44% higher than that of CYPMPO. The results indicate that DBCYP and PhCYP may be the spin traps as useful as CYPMPO either in aqueous or non-aqueous medium.

Синтез и биологическая активность 2,3-<i>бис</i>-(2-оксоилиден)-1,3,4,6-тетрагидрохиноксалинов

Конденсацией алкилметилкетонов с диэтилоксалатом и 1,2-диаминобензолом получены 2,3-бис-(2-оксоилиден)-1,3,4,6-тетрагидрохиноксалины (II – V). С помощью спектральных методов анализа выявлены четыре изомерные формы, обсуждаются особенности строения синтезированных соединений. Исследована биологическая активность полученных соединений. Обнаружено, что синтезированные соединения обладают низкой токсичностью. Выявлено, что (1Z,1’Z)-1,1’-(1,4-дигидрохиноксалин-2,3-диилиден)дибутан-2-он (соединение II) обладает антиноцицептивной активностью, превышающей активность метамизола натрия. Антиоксидантная активность на модели оценки окислительной устойчивости бактерий Escherichia coli BW 25113 в присутствии 3 мМ раствора пероксида водорода также наиболее выражена у соединения II, соединение V обладает прооксидантной активностью. Соединения показали высокую антирадикальную активность в реакции связывания дифенилпикрилгидразила (ДФПГ), которая не уступает тролоксу.

Cold-surface photochemistry of selected organic nitrates.

Reflection-absorption infrared (RAIR) spectroscopy has been used to explore the low temperature condensed-phase photochemistry of atmospherically relevant organic nitrates for the first time. Three alkyl nitrates, methyl, isopropyl, and isobutyl nitrate together with a peroxyacyl nitrate, peroxyacetyl nitrate (PAN), were examined. For the alkyl nitrates, similar photolysis products were observed whether they were deposited neat to the gold substrate or codeposited with water. In addition to peaks associated with the formation of an aldehyde/ketone and NO, a peak near 2230 cm(-1) was found to emerge in the RAIR spectra upon UV photolysis of the thin films. Together with evidence obtained by thermal programmed desorption (TPD), the peak is attributed to the formation of nitrous oxide, N2O, generated as a product during the photolysis. On the basis of the known gas-phase photochemistry for the alkyl nitrates, an intermediate pathway involving the formation of nitroxyl (HNO) is proposed to lead to the observed N2O photoproduct. For peroxyacetyl nitrate, CO2 was observed as a predominant product upon photolytic decomposition. In addition, RAIR absorptions attributable to the formation of methyl nitrate were also found to appear upon photolysis. By analogy to the known gas-phase and matrix-isolated-phase photochemistry of PAN, the formation of methyl nitrate is shown to likely result from the combination of alkoxy radicals and nitrogen dioxide generated inside the thin films during photolysis.

A Concise Account of the Chemistry of Valuable Alkyl(methyl)maleic Anhydrides

A large number of significant bioactive natural and synthetic alkyl(methyl)maleic anhydrides are known in the contemporary literature. A broad range of suitably functionalized substrates have been tailored to accomplish concise and efficient syntheses of an array of alkyl(methyl)maleic anhydrides employing a variety of elegant synthetic strategies. This review presents a brief literature account of the isolation and activity of these important target compounds with a special emphasis on their synthesis. 1 Introduction 2 Recent Synthetic Strategies towards the Natural and Unnatural Alkyl(methyl)maleic Anhydrides 2.1 Dimethylmaleic Anhydride 2.2 Ethyl/hexyl/octyl(methyl)maleic Anhydrides 2.3 Chaetomellic Anhydrides A–C 2.4 Tyromycin A 2.5 Aspergillus Acids A–D 2.6 Tautomycin and Tautomycetin 2.7 Lindenanolide E, Itaconitin, Graphenone and 2,3-Didehydrotelfairic Anhydride 2.8 Synthetic Analogues of Alkyl(methyl)maleic Anhydrides 3 Summary

Controlled separation of low temperature coal tar based on solvent extraction–column chromatography

The heavy tar (H-tar) of low temperature coal tar was collected from a low temperature carbonization plant in Shanbei. H-tar was separated into eight fractions by silica-gel column chromatography (SGCC) with a binary eluent of n-hexane and ethyl acetate (EA). A series of alkanes (C14–C28), phenolic compounds and aromatic nitrogen species were fractionated from H-tar by SGCC and analyzed by gas chromatography–mass spectrometry (GC–MS). Most of the GC–MS detectable phenolic compounds are phenol, cresol, xylenol, C3–C4 alkyl phenols, indanols, naphthalenols, methyl naphthalenols, benzenediols, fluorenols, phenanthrols and pyrenol, among which cresol is the most abundant one and pyrenol is the largest molecular weight one. According to the change rule of phenolic compounds with the polarity of eluting solvents, the solvent extraction–column chromatography (SECC) device and crude phenol recovery processing have been designed and developed, which could realize the separation of neutral oil, pitch and crude phenol from low temperature coal tar.

Diglycolamide-functionalized task specific ionic liquids for nuclear waste remediation: extraction, luminescence, theoretical and EPR investigations

A 3.6 × 10−2 M solution of a diglycolamide-functionalized task specific ionic liquid (DGA-TSIL) in [C4mim][NTf2] was used for the extraction of actinides (mainly Am) and other elements present in high level nuclear waste. The extraction of Eu3+ was relatively higher than that of Am3+ conforming to the mechanism displayed by other diglycolamide extractants such as TODGA (tetraoctyl diglycolamide). The distribution ratio values decreased in the presence of simulated high level waste (SHLW) as compared to those obtained with pure tracers. The nature of the extracted species was established by the slope analysis method which suggested 1 : 2 species for the extraction of Am3+ and Eu3+. Calculation of the Judd–Ofelt parameters from the luminescence data of the Eu3+ complexes indicated that the structure of the extracted complexes exhibits S4 symmetry. Theoretical calculations showed virtually no difference between the structures of the complexes of Am3+ and Eu3+. The nature of the radiolytic degradation products was analyzed by electron paramagnetic resonance (EPR) spectroscopic measurements revealing the presence of alkyl imidazolium and methyl radicals.

Theoretical studies on the pyrolysis of (Thion)carbonates

MP2/6-31G(d) was employed to investigate the theoretical calculations on the pyrolysis of alkyl methyl (thion)carbonates, where alkyl groups referred to ethyl, isopropyl and t-butyl groups. Nine possible pathways were considered for the pyrolysis of alkyl methyl thioncarbonates, while only seven possible pathways were found to pyrolyze alkyl methyl carbonates. Both of them had three pathways to generate the desired alkene products. Not only thermal elimination pathways were calculated, other possible mechanisms, such as rearrangements and nucleophilic substitutions, were also considered. The progress of the reactions was also investigated by the calculation of Wiberg bond indices at MP2/6-31G(d) level.

Effect of the cation on the interactions between alkyl methyl imidazolium chloride ionic liquids and water.

A systematic study of the interactions between water and alkyl methyl imidazolium chloride ionic liquids at 298.2 K, based on activity coefficients estimated from water activity measurements in the entire solubility range, is presented. The results show that the activity coefficients of water in the studied ILs are controlled by the hydrophilicity of the cation and the cation-anion interaction. To achieve a deeper understanding on the interactions between water and the ILs, COSMO-RS and FTIR spectroscopy were also applied. COSMO-RS was used to predict the activity coefficient of water in the studied ionic liquids along with the excess enthalpies, suggesting the formation of complexes between three molecules of water and one IL molecule. On the basis of quantum-chemical calculations, it is found that cation-anion interaction plays an important role upon the ability of the IL anion to interact with water. The changes in the peak positions/band areas of OH vibrational modes of water as a function of IL concentration were investigated, and the impact of the cation on the hydrogen-bonding network of water is identified and discussed.