Hydrogen Malonate Research Articles

Structures of a partially deuterated sodium trihydrogen dimalonate and sodium hydrogen malonate (a reinvestigation) at 120 K

Na + .C 3 (H,D)H 2 O 4 - .C 3 (H,D)H 2 O 4 cristallise sans deuterium dans Pnma avec a=8.484, b=6.859, c=14.950A, Z=4, T=120K; affinement jusqu'a R=0.031. Na + .C 3 H 3 O 4 - cristallise dans P2 1 /c avec a=6.671, b=7.390, c=9.359A, β=100.49°, Z=4, T=120K; affinement jusqu'a R=0.025. La molecule d'acide malonique contient une liaison hydrogene intramoleculaire courte de longueur 2.532A

Knoevenagel Reactions of 6,7-Dihydropyrrolo[2,3-c]azepine-4,8(1H,5H)-dione: An Approach to the Synthesis of Pyrrolic Marine Natural Products

The title compound undergoes reaction with diethyl malonate or ethyl hydrogen malonate in the presence of TiCl4 to give a mixture of endocyclic and exocyclic products, (5) and (6) or (13) and (14). The latter compounds have been decarboxylated and brominated to give the allylic bromide (18). Model experiments to substitute the bromine with amines suggest this compound would prove to be only a mediocre intermediate for the synthesis of the pyrrolic guanidine (2) found in Phakellia flabellata .

Structure of methylammonium hydrogen malonate (I) and methylammonium malonate (II)

Structure of methylammonium hydrogen malonate (I) and methylammonium malonate (II)

The hydrolysis products of cis-diamminedichloroplatinum(II) 5. The anation kinetics of cis-Pt(X)(NH 3) 2(OH 2) + (XCl, OH) with glycine, monohydrogen malonate and chloride

The spectrophotometrically determined rate constants, k obs (s −1), for the anation of cis-PtCl(NH 3) 2(OH 2) + with glycine (Nu=gly at pH=7.4), or sodium hydrogen malonate (Nu=Hmal − at pH=4.3) can be represented by the equation k obs= k o+ k Nu[Nu], where k o is an hydrolysis rate constant independent of the nucleophile concentration but dependent on pH, and k Nu is a nucleophile dependent path. With Nu=Hmal −, k o∼0 and the first step is monodentate coordination, followed by a second ( k cy), nucleophile independent path, due to ring closure. With Nu=gly, the ring closure reaction is sufficiently fast as to appear synchronous with coordination and k o is the base hydrolysis rate constant for cis- PtCl(OH)(NH 3) 2 at pH=7.4. Kinetic parameters associated with the anation are k Hmal (25.0 °C, pH=4.3, I=1.0 M)=9.90×10 −4 M −1 s −1, Δ H ≠=74.8 kJ mol −1, Δ S ≠=−52 J K −1 mol −1; k gly (25.0 °C, pH=7.4, I=1.0 M) 2.75×10 −4 M −1 s −1, Δ H ≠=62.7 kJ mol −1, Δ S≠=−103 J K −1 mol −1; k cy (25.0 °C, pH=4.3, I=1.0 M)=1.03×10 −5 s −1, Δ H ≠=88.9 kJ mol −1, Δ S ≠=−42 J K −1 mol −1. The rate ( k 3, s −1) of the chloride release from cis-PtCl(OH)(NH 3) 2to give cis-Pt(OH)NH 3) 2(OH 2) + and rate of chloride uptake (k −3, M −1 s −1) have been measured at pH=7.4. Kinetic parameters are k 3=2.39×10 −5 s −1 (25.0 °C, pH=7.4, I=1.0 M) Δ H ≠=82.4 kJ mol −1, Δ S ≠=−57 J K −1 mol −1 and k −3=9.37×10 −4 M −1 s −1 (25.0 °C, pH=7.4, I=1.0 M), Δ H ≠=61.7 kJ mol −1 Δ S ≠=−96 J K −1 mol −1. From these rate constants, K 3=( k 3[ k −3] −1) is calculated to be 2.55×10 −2 at 25.0 °C. These data have been used to comment on the nucleophilicity of cis-PtCl(NH 3) 2(OH 2) +.

Manganese(III) or Cobalt(III)-Mediated Oxidative Radical Reactions of Terminal Dienes. One-Pot Synthesis of Bis(dihydrofuran)s

Abstract The reactions of terminal dienes such as 1,4-pentadienes and 1,5-hexadienes with tris(2,4-pentanedionato)-manganese(III) ([Mn(acac)3]) gave α,ω-bis(dihydrofuryl)alkanes (abbreviated bis(dihydrofuran)s, hereafter) in good yields. The reactions with tris(2,4-pentanedionato)cobalt(III) ([Co(acac)3]) instead of [Mn(acac)3] yielded the same bis(dihydrofuran)s quantitatively. The dienes also reacted with ethyl 3-oxobutanoate in the presence of manganese(III) acetate ([Mn(OAc)3]) or cobalt(III) acetate ([Co(OAc)3]) to produce the corresponding bis(dihydrofuran)s. The reactions of 1,3-butadienes with the manganese(III) or cobalt(III) complexes afforded only mono(dihydrofuran)s and oxidative rearrangement products, but the corresponding bis(dihydrofuran)s were not formed. The reaction of 1,5-hexadienes with ethyl hydrogen malonate in the presence of [Mn(OAc)3] did not give bis-annulated products, but mono(γ-lactone)s in moderate yields. The synthetic applications and limitations of the bis(dihydrofuran)s formation are discussed.

Ab initio SCF and mølleb-plesset calculations on the hydrogen bond in hydrogen malonate: effects of neighbour ions and polarizable medium

Energy calculations at the SCF level with full geometry optimization and constraint to C 2v symmetry were done on hydrogen malonate using the MINI-1, 4-31G, 4-31 (+)G, 6-31 + + G, 6-31G ∗∗ and 6–31 + + G ∗∗ basis sets. The energy differences between both forms, indicative of the adiabatic potential barrier, are in the region of 2 kcal mol −1 and thus in favour of the asymmetrically placed proton, except for the calculation using the minimal base. Correction for correlation at the MP2 level, applied to the SCF calculated geometries, lowers the potential barrier. Nonadiabatic barriers at the HF level are substantially higher. Lithium ions placed 3 Å and 5 Å from the carboxyl groups induce a difference of ca. 19 kcal mol −1 between the two proton positions. The potential barrier is raised by the effect of the solvent cavity. This effect stabilizes by 7.75 kcal mol −1 the conformation with one carboxylic group perpendicular to the other relative to one with the intramolecular hydrogen bond.

Intramolecular hydrogen bonding in acid malonates. Infrared, NMR and ab initio MO investigations

The infrared spectra of solid benzylammonium and anilinium hydrogen malonates and their solutions in DMSO suggest the existence of intramolecular hydrogen bonding in the solid phase and, with the former salt, also in DMSO solution. The latter salt readily transforms into an intermolecularly bonded form which seems to be also present in DMSO solution. From 1H and 13C NMR spectra of these and other acid malonates we conclude that interactions between the intramolecularly bonded malonate and aminic cations as well as with water take place in solution and that the bridging proton participates in rapid exchange. The proton potential in hydrogen malonate appears to be easily deformed by intermolecular effects and this is simulated by ab initio calculations. Isolated hydrogen malonate would have a symmetrical potential with vanishing barrier whereas a polarizable medium increases it. Slightly asymmetrically placed ions push the proton off-centre.

Structures of benzylammonium hydrogen malonate (I) and 4-picolinium hydrogen malonate (II)

C 7 H 10 N + •C 3 H 3 O 4 − (I) cristallise dans P1 avec a=5,455, b=8,788 et c=11,060 A, α=83,67, β=86,18 et γ=78,07°, Z=2; affinement jusqu'a R=0,039•C 6 H 8 N + •C 3 H 3 O 4 − (II) cristallise dans P2 1 /n avec a=3,955, b=21,663 et c=11,259 A, β=99,33°, Z=4; affinement jusqu'a R=0,039. Deux liaisons intramoleculaires courtes asymetriques ( 2,430 et 2,493 A respectivement pour I et II) stabilisent les ions hydrogenomalonates plans. Les groupes benzylammonium sont lies aux hydrogenomalonates par trois liaisons hydrogene intermoleculaires, tandis que les ions picolinium-4 leur sont lies par une seule liaison hydrogene courte

Ionic interactions in aqueous solutions of organic electrolytes Activity coefficients for (sodium chloride + sodium hydrogen malonate)(aq) at 298.15 K. Applications of Scatchard's and of Pitzer's equations

Activity coefficients for {NaCl( m A) + NaHMal( m B)}(aq) (where Mal stands for the malonate anion), obtained from e.m.f. measurements, are given. The measurements were carried out at stoichiometric ionic strengths of 0.5, 1.0, 2.0, 3.0, and 4.0 mol · kg −1 and at a series of ionic-strength fractions y B = m B (m A + m B ) within each of these ionic strengths. The results obtained were analysed by the Scatchard and the Pitzer equations; it was found necessary to consider higher-order mixing parameters to describe the behaviour properly throughout the molality ranges studied. From this it could be deduced that some ionic association, and especially dimerization of the HMal − anions, must take place. The mixing parameters found are discussed in terms of the ionic interactions.

Crystal and molecular structure of cesium hydrogen malonate

The title compound is C3H3O4Cs, CsHM, monoclinic,P21/c,a=8.393 (3),b=7.960(2),c=9.023(2) A,β=92.11(2)°. The structure was solved by the heavy-atom method and refined by least-squares techniques to anR factor of 0.023 for 760 observed reflections. The CsHM has no internal symmetry and one carboxy group, but not the other, is twisted almost at right angles (96°) to the plane of the three central carbon atoms. The hydrogen malonate anions are linked together by two short and symmetrical O-H⋯O hydrogen bonds [2.468(4) and 2.482(4) A]. The structure consists of hydrogen malonate chains cross-linked by the Cs+ ion. The IR spectrum of CsHM has been analyzed.

Reaction of Olefins with Malonic Acid Derivatives in the Presence of Manganese(III) Acetate

Abstract The reaction of methylmalonic acid with mono- and disubstituted olefins in the presence of manganese(III) acetate yielded 2-carboxy-2-methyl-4-butanolides in moderate to good yields. The reactions of bromomalonic acid and chloromalonic acid with a variety of olefins gave 2-halo-4-butanolides and/or 2-buten-4-olides. The reaction of ethyl hydrogen malonate with olefins in the presence of manganese(III) acetate yielded 2-ethoxycarbonyl-2-buten-4-olides, 2-ethoxycarbonyl-2-ethenyl-4-butanolide, 2,7-dioxaspiro[4.4]nonane-1,6-diones, 2-ethoxycarbonyl-4-butanolide, and ethyl 3-butenoate. These reactions can be accounted for in terms of a free-radical mechanism involving substituted dicarboxymethyl radicals.

Synthesis, characterization and 1H NMR studies of [Co(en) 2(malH) 2]ClO 4·H 2O

The trans-[Co(en) 2(malH) 2]ClO 4·H 2O complex was prepared by the reaction of sodium hydrogen malonate with [Co(en) 2(H 2O 2](ClO 4) 3 in the presence of a large concentration of perchlorate ion. It showed a three-band visible spectrum (γγ max 357, 448 and 542.6 nm), diagnostic of a trans-MA 4B 2 system and gave characteristic IR bands as expected for a trans-bisethylenediamine cobalt(III) complex. The 1H NMR spectrum in DMSO- d 6 revealed a broad band at 5.8 ppm assignable to the amino hydrogen and a single band at 2.68 for the ethylene group of the chelate ring. The ▪ group of the hydrogen malonate ion appeared as a sharp singlet at 2.95 ppm and integration showed the presence of two bimalonate groups. The reactive methylene protons were found to be exchangeable. Ion association by counter ions of the complex ion in DMSO- d 6 showed no preference among amino protons. This is as expected for trans complexes with D 2 h -symmetry.

A single crystal and polycrystalline study of potassium hydrogen malonate using inelastic neutron scattering

The incoherent ineleastic neutron scattering spectra of single and polycrystal samples of potassium hydrogen (deuterium) malonate have been obtained. These spectra have been assigned in concordance with optical spectra except for the location of the antisymmetric hydrogen bond stretch ν as (OHO) which we observe at 470 cm −1. The corresponding band in the spectrum of the deuterated sample occurs at 411 cm −1. The CO 2 scissoring mode was also observed with significant intensity. These results are interpreted as a mixing of the two modes. This explains the rotation of ν as (OHO) displacement vector. This vector lies, not along an O ⋯ O direction, but along a C ⋯ C direction.

Alkaline hydrolysis of methyl hydrogen malonate in water-organic solvents

Kinetics of alkaline hydrolysis of methyl hydrogen malonate in water-methanol, water-dioxane, water-tert-butyl alcohol and water-ethylene glycol mixtures was examined. The valuse of the transfer functions of the activated complex δmμ≠ from water to the first two mixed media were calculated from the measured solubilities of tetrabutylammonium hydrogen malonate, the activation Gibbs energies and the known values of transfer functions for tetrabutylammonium and hydroxide ions. Some conclusions concerning the effect of a nonaqueous component of the solvent on solvation of the reactants and the activated complex have been drawn from the experimental data obtained.

A synthesis of 2-deoxy-3-0-methyl-1,4-aldonolactones

A practical synthetic route to 2-deoxy-3-0-methyl-1,4-aldonolactones is achieved. Isopropylidene derivatives of aldehyde sugars 1, (free or in lactol form), reacted with methyl hydrogen malonate to give α,β-unsaturated esters 2. In the case of lactols, the R group in 2 is not identical to the R in 1 (epimerisation occurs). Base-catalysed addition of methanol to the esters 2, afforded the epimeric ethers 3, acid hydrolisis of which yielded the 2-deoxy-3-0-methyl-1,4-aldonolactones 4. Degradation of the sugar chain permitted the assignment of the absolute configuration on C-3.

ENDOR Enhancements and relaxation properties of the −OOCĊHCOO − radical in a KH malonate single crystal

ENDOR enhancements and linewidths of the a proton in the −OOCĊHCOO − radical included in a potassium hydrogen malonate single crystal were determined in the three principal planes of the hyperfine tensor. In two planes the ENDOR intensities are very anisotropic, whereas in the third a nearly constant intensity is found. Very strong ENDOR signals (up to 15% of the EPR intensity) are detected near the crossing points of the “ββ” and “βα” energy levels. ENDOR enhancements were calculated by the method developed by Freed and co-workers, taking into account the anisotropies of transition moments and spin-lattice transition probabilities. Calculated intensities are in good agreement with the experimental ones. The dependence of ENDOR intensities on transition moments is very small, whereas they are strongly dependent on spin-lattice transition probabilities. Orientationally dependent W N values must be introduced in the calculations. A strong contribution to W N by the modulation of the dipolar hyperfine field due to the electron relaxation must be assumed. The electron spin-lattice relaxation mechanism is isotropic, being the phonon modulation of the spin-orbit coupling. The W E values giving the best agreement between experimental and calculated enhancements are in the range 10 2 to 5 × 10 2 s −1.

ChemInform Abstract: Acylation Reaction of mß‐Unsaturated β‐Keto Esters and of Ethyl Hydrogen Malonate. Synthesis of γ‐Alkenyl‐5‐ethoxycarbonyl‐2,3‐dihydro‐4H‐pyran‐4‐ones and 4,5‐Dioxo‐2,3,7,8‐tetrahydro‐4H,5H‐pyrano[4,3‐b]pyran Derivatives. Synthesis of 3‐Alkenyl‐4‐oxo‐6,7‐dihydro‐1H‐pyrano[4,3‐c]pyrazole Derivatives.

AbstractAcylbrenztraubensäureester (I) reagiert mit Magnesium‐ethylat und Säurechloriden (II) zu den Enolketonen (III), die zu (IV) und mit Schwefelsäure weiter zu (Va) kondensiert werden.

An ab initio study of intramolecular hydrogen bonding in malonic acid and its monoanion

Ab initio calculations have been performed on malonic and hydrogen malonate acids. The studied conformations were optimized at the STO-3G level and the STO-3G optimal geometries used for single point 4-31G calculations. For malonic acid the most stable conformation occurs in the absence of hydrogen bonding. In hydrogen malonate acid a symmetrical C 2V hydrogen-bonded structure is found to be the most stable and a barrier height of 4.0 kcal mol −1 is obtained with the 4-31G basis set for the single-minimum hydrogen potential energy curve.

Acylation reaction of γ,β‐unsaturated β‐keto esters and of ethyl hydrogen malonate. Synthesis of 6‐alkenyl‐5‐ethoxycarbonyl‐2,3‐dihydro‐4H‐pyran‐4‐ones and 4,5‐dioxo‐2,3,7,8‐tetrahydro‐4H,5H‐pyrano[4,3‐b]pyran derivatives

AbstractThe syntheses of 6‐alkenyl‐5‐ethoxycarbonyl‐2,3‐dihydro‐4H‐pyran‐4‐one derivatives by acylation of γ,β‐unsaturated β‐keto esters or by diacylation of ethyl hydrogen malonate with α,β‐unsaturated acyl chlorides are described. These compounds were converted to 4,5‐dioxo‐2,3,7,8‐tetrahydro‐4H,5H‐pyrano[4,3‐b]pyran derivatives.

Studies of radical pairs in potassium hydrogen malonate

The cause of irreversible temperature changes in the fine structure of radical pairs in potassium hydrogen malonate previously observed by E.S.R. has been examined in detail by ENDOR. The results show that these changes can be attributed to structural relaxations of the stressed molecules following the abstraction of hydrogens by X-rays at 77 K from the methylene carbons. The appearance of different modifications of pairs is then explicable on the basis of symmetry conditions, which change during annealing of the radicals. In addition the ENDOR results demonstrate that the hyperfine interaction in radical pairs differs from the appropriate coupling constant of the corresponding monoradical in virtue of the transferred hyperfine interaction. It is shown that the transferred hyperfine interaction could be a measure for the direct overlap of the unpaired electrons in radical pairs.