Abstract  Five malonanilide derivatives (M1-M5) were prepared by the reaction of ethyl malonate with aniline derivatives. These compounds were investigated as new stabilizers for double-base propellants (DBPs). The evaluation process has been performed through thermal stability tests, thermal analyses measurements (TGA and DSC) and kinetic parameters calculations (E(a)). The results of the new stabilizers were compared with the results of the classical stabilizer N, N-diethyldiphenyl urea. It has been found that o- and p-dinitromalonanilides, in particular, showed better stability effect for DBPs than the classical one.

Abstract  The gas-phase hydrogenation of diethyl malonate to 1,3-propanediol has been studied over Cu/SiO2 nanoparticles. The influence of the ammonia amount was investigated on the catalyst properties and moreover on the hydrogenation of diethyl malonate to 1,3-propanediol in the liquid hourly space velocity of 0.72-1.8 h(-1). N-2-physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and H-2-temperature-programmed reduction were used to characterize the textural and structural properties of Cu/SiO2 catalysts. The amount of ammonia played a profound effect on the morphology and the dispersion of copper species. Cu/SiO2 catalyst with the molar ratio of n(NH3 center dot H2O)/n(Cu2+) = 2 gained better dispersion, smaller particle size and less dependence to agglomerate of copper species and thus had a higher selectivity for 1,3-propanediol.

Abstract    The experiments of immiscible liquid-liquid mixing in a stirred vessel were performed in order to relate the drop size distribution with impeller revolutional speed and to examine the applicability of a new formula of the drop size distribution presented by authors. The new formula based on an information entropy concept is composed of the product of the original distribution function and the realizable probability function derived under following two assumptions. First, the break-up of a drop occurs when the external force/energy exceeds the internal force/energy of the drop. Second, there is a limitation in the drop size which can exist in actuality. In the present work, ethyl malonate and water were adopted as a dispersed phase and a continuous phase, respectively. By setting the dilute volume fraction of the dispersed phase, the break-up of drops seems to be dominant while coalescence could be negligible. Impeller revolutional speed was varied from 210 to 300 rpm. A photographic method was utilized to measure the drop size. It is clarified that the new formula can express sufficiently the experimental data. Additionally, the drop size distribution for the number density derived from the new formula is also in agreement with the experimental data. The usefulness of the newly expressed formula is confirmed by applying it to other experimental data presented by other investigators. The parameter L as a mean size in the new formula is correlated with the impeller revolutional speed and it is made clear that L is in proportion to the impeller revolutional speed to the minus 1.2 power like the case of the Sauter mean drop size and the maximum drop size. The other parameter B as a coefficient is considered to be affected only by the ratio of the viscosity of dispersed phase to that of continuous phase of the liquid-liquid system.

Abstract  The kinetics of Tl(III) perchlorate oxidation of some active methylene compounds viz. ethyl acetoacetate and diethyl malonate has been studied in acetic acid-water mixture in the presence of perchloric acid.

The reactions show first order in oxidant while the order in both the esters vary from one to zero. The order with respect to hydrogen ion is one for ethyl acetoacetate oxidation while one to zero in malonic ester oxidation. Added Cl- inhibits the rate of reactions. The effect of variation of ionic strength of the medium has been investigated. The stoichiometry of the title reaction is found to be 1:2. The activation parameters have been evaluated. Based on these finding a probable mechanism has been proposed.

Abstract  Enantiomeric cyclic, five-melnbered alcohols and tic-diols were converted into the corresponding mono- and bis(aryl-sulfanyl) derivatives with complete inversion of configuration at one or both stereogenic centers. The thus obtained chiral thioethers were tested in the Pd-catalyzed allylic alkylation of dimethyl malonate with rac-1,3-diphenyl-2-propenyl acetate. The purely S,S-donating C-2-symmetric chiral ligands showed poor to moderate enantioselectivity (up to 42%), while 1-alkyl-3,4-bis(aryl-thio)pyrrolidines afforded much higher results, 81-89% ee. When chiral pyrrolidine mono-thioethers were applied the observed enantioselectivity improved further to 86-90% ee. These results suggest that the pyrrolidine thioethers served as the N(sp(3)),S-donating chiral ligands. Examination of molecular models showed that the sense of stereoinduction, namely (R)-product from with (3R)-1-benzyl-3-(arylthio)pyrrolidine is in agreement with the nucleophilic attack being directed at the allylic carbon located trans to the sulfur atom in the intermediate eta(3)-allylpalladiuln complex. (C) 2004 Elsevier Ltd. All rights reserved.

Abstract  Possibilities for enhancing the performance and selectivity of malonic ester monoalkylation by optimization of phase-transfer catalysis conditions were studied. Two-phase catalyst systems containing the organic phase and a solid base are shown to be more effective in comparison with the systems consisting of the organic phase and aqueous solutions of deprotonating agents. The performance of systems composed of the organic phase and an aqueous base solution can be increased by stepwise introduction of a deprotonating agent into the system. An effective catalytic system with an organic phase consisting of reactants and solid potassium hydroxide with small admixtures of water is suggested, which makes it possible to selectively conduct the monoalkylation reaction of malonic ester under mild conditions in the presence of polyethylene glycol.

Abstract  The crystal structure of the complex [CuL(OH)(2)](ClO4)(2).H2O; L = N,N'-bis(2-pyridylmethylene)-1,3-diamino-2,2-dicarboxyethylpropane, determined for the first time, reveals a penta-coordinated copper(II) centre in a distorted square-pyramidal geometry with a weakly bonded axial water molecule, In order to assess possible routes to the putative free ligand N,N'-bis(2-pyridylmethylene)-1,3-diaminopropane-2-carboxylic acid the behaviour (stability) of the complex towards both acid and alkaline aqueous solution has been investigated. In 1.0 M acidic chloride media at 25 degreesC the complex undergoes slow decomposition in two stages giving 2-pyridylmethylammonium chloride, formaldehyde and diethylmalonate in addition to aqueous Cu2+. The initial fast stage has both H+-dependent (5.32 +/- 0.18 x 10(-5) M-2 s(-1)) and independent (1.59 +/- 0.10 x 10(-5) s(-1)) paths, the latter believed to reflect rapid chloride equilibration at the labile axial site followed by rate determining isomerisation to place a Cu-NH bond at the axial site leading to Cu-N bond cleavage. The rate constant for the H+-dependent faster stage carries a [H+](2) dependence suggesting that here protonation of both secondary NH groups occurs within the rate-determining step prior to decomposition, Assistance from the axial site is also proposed. Absorbance changes monitored as a function of [H+] for the similar to 10 x slower second stage suggest that it may involve intermediates resulting from the H+-independent initial step. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract  2,5-Dichloro-4,4-ethylenedioxy-3-phenylsulfonyl-2-cyclopentenone reacts with diethyl malonate potassium salt according to the Ad(N)E pattern with replacement of chlorine atoms at the double C=C bond, while the reaction of the same substrate with allylcuprate is not selective, and it follows several pathways.

Abstract  Reaction of the appropriate reagent Fc(CH2)(n)CHRX (1-3, 6, and 9) with sodium salt of diethyl malonate in dry xylene gave 81-91% of the corresponding diethyl (ferrocenylalkyl)malonate or diethyl ferrocenyl(phenyl)alkylmalonate (11). Using Fc(CH2)(n)CHRX (4, 7, 8 and 10) under similar reaction conditions, transesterification products - ethyl ferrocenylalkyl malonates or ethyl ferrocenyl(phenyl)alkyl malonates (12) were obtained. Reduction of condensation products 11 with lithium aluminium hydride in diethyl ether gave the corresponding diols 13 (45-66%), which will be in further studies subjected to lipase-mediated transformations with vinyl acetate to chiral monoacetates. By the action of acetic anhydride on diols 13 in a benzene solution, the corresponding mono- 14 (25-52%) and diacetates 15 (36-51%) were obtained.

Abstract  In acid media, 1,3-diketones and 1,3-ketoesters can be fluorinated in high yield and often with high conversion mainly to the corresponding 2-fluoro- compounds. Diesters such as diethyl malonate do not react with fluorine under the same reaction conditions. The mechanism of these reactions has been investigated and while the identity of the electrophilic fluorinating species is uncertain, we believe that the essential features of the reaction pathway are understood.

Abstract  Copper-catalyzed C-C coupling reaction of aryl iodides with diethylmalonate in toluene at 90 degrees C gave arylated malonates using 5 mol% of Cul with hydrazone 1a as a ligand in good yields under an aerobic atmosphere. We also found Cul/hydrazone 1b in toluene to be an efficient catalytic system for C-O Coupling reactions of aryl bromides with phenols to give aryl ethers ill good yields at 110 degrees C under an aerobic atmosphere.

Abstract  A series of 16-electron Cp*Ir amide complexes with C-N chelating ligands, Cp*Ir[kappa(2)(NC)-(NHCR(2)-2-C(6)H(4))] (2a: R = C(6)H(5), 2b: R = CH(3)) and the chiral version, Cp*Ir[kappa(2)(N,C)-(R)-{NHCH(CH(3))-2-C(10)H(6)}] (2e), were obtained in good to excellent yields from reactions of 18-electron iridium amine complexes, Cp*IrCl[kappa(2)(N,C)-(NH(2)CR(2)-2-C(6)H(4))] (1a: R = C(6)H(5), 1b: R = CH(3)) and Cp*IrCl[kappa(2)(N,C)-(R)-{NH(2)CH(CH(3))-2-C(10)H(6)}] (le), with a base. The amido complexes 2 readily reacted with 2-propanol to convert into hydrido(amine) complexes 3 in almost quantitative yields. The chiral amido complex has proven to serve as an efficient catalyst for asymmetric transfer hydrogenation of acetophenone with 2-propanol, giving 1-phenylethanol with a moderate ee. The Bronsted basicity on the metal-NH moiety in the amido complexes was evaluated by deprotonation of acetic acid, dimethyl malonate, and acetone, leading to the corresponding acetato(amine) complex 4 and alkyl(amine) complexes 5 and 6, respectively, indicating that the amido-Ir complexes bearing the C-N chelate have more basic properties than those with N-sulfonylated diamine ligands.

Abstract  A macrocyclic malonic ester condensation with pyridine building blocks leads to the new bicyclic host molecule 1 with defined cavity size, the X-ray structure analysis of which reveals three convergent nitrogen donor centres; in radiotracer phase-transfer measurements 1 turns out to be remarkably selective for Ag-I cations while discriminating against Cu-I and Cu-II cations.

Abstract  We examine how the C-13 shafts of oligomers of branching polyesters made from glycerol or erythritol and the difunctional carboxylic acids malonic acid, succininc acid or glutaric acid reflect the location of the ester links on the alcohols, and whether these are influenced by a reaction of the acids at their second site. Assignments were made by observing the new shifts that appeared as the oligomers formed in reactions whose initial conditions were chosen to simplify the products; symmetry of structure was also used. Substitution parameters for each acid were obtained for each carbon in the alcohols, and found to be sensitive to whether the second function of the malonic and succinic acids had participated in ester formation. Cyclic products were discovered early in transesterification reactions of dimethyl malonate. For a fractal polyester a nomenclature is provided, an example prepared and characterized, and then shown to be modified by reactions: Fractal(G,S[-O-H]), fringed with hydroxyl groups, gave an acid-fringed fractal: Fractal(G,S[-CO-O-H]) (a hyperbranch of glycerol and succinate residues).

Abstract  BIOSIS COPYRIGHT: BIOL ABS. Retention index monitoring using thermal desorption gas chromatographic analysis was developed as a method for the verification of compounds of chemical defense interest in environmental matrices. Gas chromatography retention indices were determined by loading solid adsorbent packed sampling tubes initially with the target compounds and subsequently with a series of n-alkaline probes. The resulting chromatographic performance and gas chromatography retention indices were shown to be independent of the tube loading method. A database of gas chromatography retention indices for chemical warfare agents and simulants was compiled and, in conjunction with simultaneous flame ionizatin and flame photometric detection, applied to the identification of triethyl phosphate, tributyl phosphate and diethyl malonate in water and soil samples.

Abstract  Metal carbonate-catalyzed reactions of CH-acids (diethyl malonate, ethyl acetoacetate, ethyl cyanoacetate, and ethyl 2-acetyl- and 2-ethoxycarbonyl-5,9-dimethyldeca-4,8-dienoates) with alpha,beta-unsaturated aldehydes (acrolein, crotonaldehyde, citral) were studied in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], and in a 1-butyl-3-methylimidazolium bromide ([bmim][Br]) - benzene system. The reactions with acrolein and crotonaldehyde afforded Michael addition products, those with citral resulted in Knoevenagel addition products. Sonication increased the yields of the Michael adducts. The ionic liquid [bmim][PF6] can be recovered and repeatedly used in the reactions.

Abstract  Six new manganese(II) complexes of formulas [Mn-2(Rmal)(2)(H2O)(2)(azpy)](n) (1-3), [Mn(Phmal)(H2O)-(azpy)](n) (4), [Mn-2(Et(2)mal)(2)(H2O)(4)(azpy)(2)](n) (5), and [Mn(Bzmal)(H2O)(3)(azpy)] (6) [azpy = 4,4'-azobispyridine (1-6), Rmal = methylmalonate (Memal) (1), dimethylmalonate (Me(2)mal) (2), and butylmalonate (Butmal) (3), Phmal = phenylmalonate (4), Et(2)mal = diethylmalonate (5), and Bzmal = benzylmalonate (6)] were synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1-3 are three-dimensional compounds whose structure consists of corrugated layers of manganese(II) linked through syn-anti carboxylate (Rmal) bridges, which are pillared through the bis-monodentate azpy molecule. Complex 4 has a layered structure of manganese(II) ions connected by carboxylate (Phmal) bridges in the syn-anti coordination mode as in 1-3, the azpy group acting here as a terminally bound monodentate ligand. The structure of 5 consists of Et(2)mal-Mn(II) neutral chains linked through the azpy ligand, giving rise to a complex three-dimensional network. Complex 6 is constituted by neutral [Mn(Bzmal)(H2O)(3)(azpy)] mononuclear units, which are interlinked through O-H center dot center dot center dot O, O-H center dot center dot center dot N, and pi-pi type intermolecular interactions to afford a three-dimensional supramolecular structure. The topological analysis of these crystallographic structures shows the occurrence of four different nets: a (3,4)-connected InS-type (1-3), a binodal layered hcb (4), a uninodal CdS-type (5), and a (4,5)-connected tcs topology (6). The magnetic properties of 1-5 were investigated in the 2.0-300 K temperature range. Overall antiferromagnetic behavior occurs in 1-4 with susceptibility maxima in the range 2.8-5.5 K, the exchange pathway being provided by the syn-anti carboxylate (substituted malonate) bridge [manganese-manganese separation in the range 5.4365(3)-5.5274(1) angstrom]. Very weak antiferromagnetic interactions are observed in 5 through the trans-bis-monodentate Et(2)mal ligand, the intrachain manganese-manganese separation being 7.328(3) angstrom. The much larger manganese-manganese separation through the bis-monodentate azpy ligand in 1-5 (values greater than 13.5 angstrom) accounts for the lack of any significant magnetic interaction though this extended bridge.

Abstract  (Methyl)malonyl coenzyme A was rapidly and effectively synthesized by a two-step procedure involving preparation of N-hydroxysuccinimidyl (methyl)malonate from (methyl)Meldrum's acid, and followed by transesterification with coenzyme A. The synthesized (methyl)malonyl coenzyme A could be well accepted and assembled to 4-hydroxy phenylpropionyl coenzyme A by type III polyketide synthase from Aquilaria sinensis to produce dihydrochalcone and 4-hydroxy-3,5-dimethyl-6-(4-hydroxyphenethyl)-2H-pyrone as well as 4-hydroxy-3,5-dimethyl-6-(5-(4-hydroxyphenyl)-3-oxopentan-2-yl)-2H-pyrone.

Abstract  New types of mesitylene based tri-site containing asymmetric quaternary ammonium salts 9a and 9b have been prepared and used as efficient chiral phase transfer catalysts for enantioselective Michael addition reactions between the chalcones and diethylmalonate under mild reaction conditions such as lower concentration of base, catalyst and ultrasonic conditions with very good chemical yields (up to 98%) and ee's (up to 99%).

Abstract  A convergent, stereocontrolled construction of the cis,anti,cis-tricyclo[5.3.0.0(2,6)]decane nucleus of spatane diterpenes was achieved by 2-pi + 2-pi photocycloaddition of 2-cyclopenten-1-one, as an A-ring precursor, with a carbonyl-masked derivative of 6-methylbicyclo[2.2.1]hept-5-en-2-one as a temporarily bridged C-ring precursor. By design, the temporary bridge assures the correct stereochemical relationship between the B-ring stereocenters and the C-ring hydroxyl substituent that is present in latent form in the oxoethano bridge. Serendipitously, the bridge also fosters a favorable orientation of the photocycloaddition that contrasts with the nonselective 2-pi + 2-pi-photocycloadditions of unbridged 1-methylcyclopentenes with 2-cyclopenten-1-one. Wittig methylenation of the A-ring carbonyl in photoproduct 24 followed by hydrolysis to 25 and catalytic hydrogenation introduces a methyl group at position 1 with a 10:1 preference for the requisite stereochemistry in 26. Even higher stereoselectivity was achieved by SO2-promoted isomerization of the exocyclic C=C bond in 25 to an endocyclic disposition in 29 prior to catalytic hydrogenation. Johnson's sulfoximine method is especially effective for resolution of ketone 29. The oxoethano bridge in ketone 26n is oxidized rapidly but nonregioselectively by an H2SO4-catalyzed reaction with peracetic acid, producing a 57:43 mixture of 14 and 34. Regioselective generation of the desired lactone 14 could be accomplished by a much slower oxidation with peracetic acid and no added H2SO4. The necessary configuration at position 7 in 49 was generated stereoselectively by a novel homoallylic hydroxyl-directed, pseudointramolecular delivery of hydride to the methylenemalonic ester in the precursor 48. Conversion of the malonic ester moiety in 49 into an allylic alcohol was accomplished in 92% overall yield by monosaponification, decarboxylative condensation with formaldehyde and reduction of the resulting acrylic ester with i-Bu2AlH. Selective oxidation of the allylic hydroxyl followed by acetylation delivered acetate (+)-11a, which is identical with an oxidative degradation product from spatane diterpenes.

Abstract  Reactions of 3-phenylsulfonyl-2-trifluoromethyl-1,3-butadiene (1) with heteroatom nucleophiles such as pri-amines, pri-alcohols, and thiols afforded the addition products 2, 3, and 5 regioselectively formed via addition of nucleophiles toward double bond attaching phenylsulfonyl group. Cyclization of 2a in 2,2,2-trifluoroethanol at 60 degrees C for 2 h gave pyrrolidine 4a in good yield. Similarly, compound 1 was also reacted with diethylmalonate in the presence of NaH to give addition product 7 in good yield. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Palladium(II)-exchanged hydroxyapatite (PdHAP: for example, PdHAP-B has a Pd/Ca ratio = ca 1/200) was prepared by ion-exchanging with Ca(2+) from calcined hydroxyapatite and Pd(NO(3))(2) in water at 70 degrees C for 24 h. The ion-exchange was revealed by inductively coupled plasma analysis; Pd(2+) was almost absent in any filtrate that included over 1.6 equimolar amounts of Ca(2+) relative to the amount of Pd(2+) consumed. The PdHAP (1 mol% Pd) functioned as a catalyst for the allylic alkylation of allyl methyl carbonate with active methylene compounds such as diethyl malonate, 2-ethoxycarbonylcyclopentanone, 2-ethoxycarbonylcyclohexanone, and 2,2-dimethy1-1,3-dioxane-4,6-dione at 50 degrees C in water under air. Over 97% of the PdHAP was recovered by centrifugation followed by decantation, and the material could be reused. The catalytic activity of PdHAP accompanied by satisfactory yields of monoallylated products was maintained in ten repetitive uses for the allylic alkylation of allyl methyl carbonate with diethyl malonate at 50 degrees C for 24h in water under air. From the standpoints of yield and handling, using water as a solvent was superior to using an organic medium such as ethanol. THF or DMF. Thus, this heterogeneous PdHAP-catalyzed allylic alkylation will be one of the environmentally-benign organic syntheses. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  Decontamination of chemical agents from the skin uses both dry and wet decontamination processes. Recent studies have shown that wet decontamination frequently results in stratum corneum hydration. To evaluate the hydration effect of wet decontamination on the skin barrier function and hence on the decontamination efficiency, a series of comparative studies were carried out on human skin contaminated with the nerve agent simulant diethylmalonate, using decontamination media having different salinity and surfactants. The results showed that, compared to non-decontaminated skin, remnant diethylmalonate on decontaminated skin penetrated at an accelerated rate in the immediate 2 h following decontamination. This transient enhancement effect, ranging from 20 to 98%, was depended on the nature of the decontamination media used and was more obvious in skin samples that were decontaminated 1 h postexposure. All decontamination media exhibited this effect, with the greatest enhancement observed in the following order: anionic surfactant > cationic surfactant > non-ionic surfactant > deionized water > 0.9% saline > 9% saline.

Abstract  In the gas phase, the unimolecular isomerization of the H3COC(O)CH2CO+ cation 1 (m/z 101) into the H3CO(HO)CCHCO+ enol ion 2 by a 1,3-H shift possesses a high energy barrier and is therefore not observed. In contrast, in the cell of a FT-ICR mass spectrometer, interaction with gaseous methanol catalyzes the isomerization of 1 into its more stable isomer 2, which can be characterized by low energy collision with argon. This exothermic reaction is irreversible. Reaction with labeled methanol and ligand exchange experiments indicate the existence of two distinct reactions. By formation of a covalent bond, one reaction yields protonated dimethyl malonate while the second one leads to ion 2 by a 1,3-H transfer catalyzed by methanol. Conversely, loss of methanol from collisionally activated long-lived mit 133 cations formed by protonation of dimethyl malonate yields some mit 101 ions with structure 2, which shows that methanol catalyzes the isomerization of ion 1 within a [1, CH3OH] complex. The efficiency of different catalysts is studied in order to probe the mechanism of the isomerization processes. (C) 1998 Elsevier Science B.V.