Xn:Harmful;
141-82-2Relevant articles and documents
Investigation of Radical Reactions Important in the Gyoergyi-Turanyi-Field Model of the Belousov-Zhabotinskii Reaction
Foersterling, Horst-Dieter,Stuk, Linda
, p. 7320 - 7325 (1991)
In the Gyoergyi-Turanyi-Field (GTF) model of the Belousov-Zhabotinskii (BZ) reaction, malonyl radicals (MA.) and bromomalonyl radicals (BrMA.) are assumed to be important intermediates.The hydrogen abstraction reactions MA. + BrMA -> MA + BrMA. (a) and BrMA. + MA -> BrMA + MA. (b) (MA, malonic acid; BrMa, bromomalonic acid) transfer from free-radical nature of the malonyl species to the bromomalonyl species and vice versa.The rates of these two reactions determine in part the relative importance of these radical intermediates.Another key radical reaction is BrMA. + Ce4+ + H2O -> BrTTa + Ce3+ (c) (BrTTA, bromotartronic acid), which is a source of Br- through decomposition of BrTTA in the model.It has been deduced from ESR and spectrophotometric experiments that reactions a-c do not contribute to the chemistry of the BZ reaction.Numerical integration of the GTF rate equations, omitting reactions a-c, shows no oscillation in BZ systems with high initial concentrations of BrMA.Experimentally, these systems exhibit oscillations with no induction period.
MALONATED ANTHOCYANINS IN MALVACEAE: MALONYLMALVIN FROM MALVA SYLVESTRIS
Takeda, Kosaku,Enoki, Shigeki,Harborne, Jeffrey B.,Eagles, John
, p. 499 - 500 (1989)
A new anthocyanin, malvidin 3-(6"-malonylglucoside)-5-glucoside has been characterized in both wild and cultivated forms of Malva sylvestris.Thus the classic source of the anthocyanin, malvin, actually contains the pigment in the flowers in malonated form.Malonated anthocyanins were also detected in Althaea rosea, Lavatera olbia and a Sphaeralcea sp. but they were not present in five other species in the family. - Keywords: Malva sylvestris; Malvaceae; mallow; flowers; malvidin 3-(6"-malonylglucoside)-5-glucoside; malvin.
An unusual acylated malvidin 3-glucoside from flowers of Impatiens textori Miq. (Balsaminaceae)
Tatsuzawa, Fumi,Saito, Norio,Mikanagi, Yuki,Shinoda, Koichi,Toki, Kenjiro,Shigihara, Atsushi,Honda, Toshio
, p. 672 - 674 (2009)
Acylated malvidin 3-glucoside was isolated from the purple flowers of Impatiens textori Miq. as a major anthocyanin component along with malvidin 3-(6″-malonyl-glucoside). Its structure was elucidated to be malvidin 3-O-[6-O-(3-hydroxy-3-methylglutaryl)-β
Exploring the Promiscuous Enzymatic Activation of Unnatural Polyketide Extender Units in Vitro and in Vivo for Monensin Biosynthesis
Grote, Marius,Schulz, Frank
, p. 1183 - 1189 (2019)
The incorporation of new-to-nature extender units into polyketide synthesis is an important source for diversity yet is restricted by limited availability of suitably activated building blocks in vivo. We here describe a straightforward workflow for the biogenic activation of commercially available new-to-nature extender units. Firstly, the substrate scope of a highly flexible malonyl co-enzyme A synthetase from Streptomyces cinnamonensis was characterized. The results were matched by in vivo experiments in which the said extender units were accepted by both the polyketide synthase and the accessory enzymes of the monensin biosynthetic pathway. The experiments gave rise to a series of predictable monensin derivatives by the exploitation of the innate substrate promiscuity of an acyltransferase and downstream enzyme functions.
Diverse structural assemblies of a series of ninhydrin derivatives: Quantitative analyses from experimental and theoretical studies
Hundal, Geeta,Kapoor, Kamal K.,Mahajan, Sheena,Saini, Yeshwinder,Seth, Saikat Kumar
, (2021)
Three ninhydrin derivatives (2–4) have been synthesized where the reaction of ninhydrin with Meldrum's acid yielded [3.3.3] propellanoid (2) and ethyl 2,2-bis (1,3-dioxo-2,3-dihydro-1H-inden-2-yl)acetate (3) while with malononitrile yielded a spiroindenopyran (4). The products being crystalline in nature and are characterized by single crystal X-ray diffraction in addition to other spectroscopic studies. X-ray crystallography reveals that solid-state structure of the title compounds exhibits C?H···π, π?π and lone-pair(l.p)···π interactions in building supramolecular assemblies. Indeed, compound (2) was stabilized through extended supramolecular C?H···π/π?π/π···H?C network whereas compounds (3) and (4) are stabilized through lone-pair (l.p)···π and π?π interaction respectively. The diverse intermolecular interactions via Hirshfeld surface analysis enables quantitative contributions to the crystal packing that exposes the similarities and differences in the interactions experienced by each compound. The distinctive energy frameworks have been calculated for individual molecules and the interaction energies suggest that the contacts are largely dispersive in nature. The binding energies associated with the non-covalent interactions observed in the crystal structures have been calculated using theoretical DFT calculations. Finally, the interplay between the interactions have been characterized by Bader's theory of “atoms-in-molecules” (AIM).
Kinetic modeling of malonylgenistin and malonyldaidzin conversions under alkaline conditions and elevated temperatures
Vaidya, Nirupama A.,Mathias, Kevin,Ismail, Baraem,Hayes, Kirby D.,Corvalan, Carlos M.
, p. 3408 - 3413 (2007)
The conversion and degradation of malonylglucosides were kinetically characterized under elevated pH/heat conditions. Malonylgenistin and malonyldaidzin were heated at 60, 80, and 100°C and pH values of 8.5, 9, and 9.5. A simple kinetic model was developed, which adequately predicted the conversion and degradation reactions. The conversion and degradation rates increased as temperature and pH increased. The rates of conversion of both malonylglucosides into their respective β-glucosides were comparable under all pH/heat treatments. However, at 100°C, the rates of degradation of malonyldaidzin were approximately double those of malonylgenistin, under all pH treatments. When malonlydaidzin was heated at 100°C and pH 9.5, degradation of the produced daidzin occurred. Therefore, an alternative kinetic model was developed to better predict the conversion and degradation of malonyldaidzin occurring at 100°C and pH 9.5. The models developed provide soy food manufacturers with guidelines for better control of the profile and level of isoflavones.
Enols derived from malonic acids as intermediates in nitrosation and halogenation
Williams,Graham
, p. 7973 - 7978 (1992)
Malonic acid, methylmalonic acid, ethylmalonic acid and phenylmalonic acid react with electropholic nitrosating agents and also with bromine and iodine via their corresponding enol or enolate forms. In most cases it is possible to make either the enolisation or reaction of the enol rate-limiting by a suitable choic of reactant concentrations and reactivity. The enolisation rate constants agree resonably well with literature values where they exist. We propose minimum figures of 1.0 x 10-8 and 1.6 x 10-8 respectively for K(E) the enolisation equilibrium constant for malonic acid and methylmalonic acid. The kinetic term second order in [malonic acid] or its derivatives (when enolisation is rate limiting) has been shown to arise from a base catalysed component to the reaction brought about by the malonate ion, which dominates at pH values greater than ca. 3.
Design of bisquinolinyl malonamides as Zn2+ ion-selective fluoroionophores based on the substituent effect
Moriuchi-Kawakami, Takayo,Kawata, Keita,Nakamura, Sho,Koyama, Yoshiaki,Shibutani, Yasuhiko
, p. 9805 - 9813 (2014)
A series of malonamides possessing two quinoline moieties were synthesized and characterized as fluoroionophores for the Zn2+ ion. We focused on the relationship between the substituents introduced to the C2-position of the malonamides and their Zn2+ ion-selectivity, exploiting the structural effect of the substituents in the design of the fluoroionophores with high selectivity. The substituents introduced to the malonamides were the methyl, benzyl and naphthalenylmethyl groups. In dimethyl sulfoxide solvent, all substituted bisquinolinyl malonamides showed excellent fluorescence sensing for the Zn2+ ion, while unsubstituted bisquinolinyl malonamide 1 displayed ratiometric sensing for the Co2+ ion. N,N′-Bis(8-quinolyl)-2-methyl-2-naphthalenylmethyl malonamide 4 exhibited the highest Zn2+ ion-selectivity against the Cd2+ ion. Although the substituents introduced into the C2-position are spatially distant from the quinoline recognition moiety, this study indicated that they greatly influenced the ion selectivities of the bisquinolinyl malonamides. Furthermore, it was demonstrated that visible fluorescence analyses could be performed on malonamide 4.
Photo-Induced Disproportionation of Iodomalonic Acid
Rabai, Gyula,Hanazaki, Ichiro
, p. 431 - 442 (1995)
The stoichiometry, equilibrium, and kinetics of the photo-induced disproportionation of iodomalonic acid to I-, I2, and tartronic acid have been studied by means of spectrophotometry and iodide selective electrode at 20.0 +/- 0.2 deg C, pH 2.0 - 4.0.At pH > 2.9, only I- and HOCH(COOH)2 are detected as major products and the reaction reaches 100percent conversion.At pH I. + .CH(COOH)2, (M2) I2 + hν 2I..While both reactions are sensitive to UV light, only M2 can be affected by visible light. (M1) and (M2) are considered to initiate a chain reaction sequence in which I. radicals oxidize iodomalonic acid.Dual effects of reaction products on the reaction rate have been observed: while iodine increases the efficiency of visible light and accelerates the reaction, malonic acid inhibits the photo-decomposition by mediating the recombination of I. radicals to I2.
Experimental and mechanistic investigation of an iodomalonic acid-based Briggs-Rauscher oscillator and its perturbations by resorcinol
Cervellati, Rinaldo,Greco, Emanuela,Furrow, Stanley D.
, p. 12888 - 12892 (2010)
Classic Briggs-Rauscher oscillators use malonic acid (MA) as a substrate. The first organic product is iodomalonic acid. Iodomalonic acid (IMA) can serve as a substrate also; thus, the first product in that case is diiodomalonic acid (I2MA). Nonoscillating iodination kinetics can be followed by absorbance at 462 nm in acidic KIO3 so long as IMA is in substantial excess over [I2]. At 25 °C, simulations lead to the two most important rate laws, and related rate constant estimates are reported. I 2MA eventually decomposes by unknown processes, but I2, O2, H2O2, and Mn2+ speed up that decomposition, liberating most of the iodine back to the solution. Resorcinol is an effective inhibitor of oscillations both in MA oscillators and in IMA oscillators. Response of an IMA oscillator to varying amounts of resorcinol is shown herein and is similar to that for MA-based oscillators. The inhibitory effect of resorcinol is diminished by addition of IMA to a MA-based oscillator. The iodination reaction between IMA and resorcinol is too slow (0.043 M -1 s-1) to account for the decreased inhibitory effectiveness of resorcinol. Rather, the decomposition of I2MA is responsible for the inhibition decrease.
