Adduct Formation Reactions Research Articles

The Synergic Extraction of Rare Earth Metals with ortho-Substituted 1-Phenyl-3-methyl-4-aroyl-5-pyrazolones and Trioctylphosphine Oxide.

The synergic extractions of rare earth metals (scandium, lanthanum and lutetium, M3+) with ortho- substituted 4-aroyl derivatives of 1-phenyl-3-methyl-5-pyrazolone (HA) and a neutral ligand, trioctylphosphine oxide (TOPO, L) in benzene were studied. Eight ortho-substituted 4-aroyl derivatives of pyrazolone have been prepared. Linear relationships between the extraction constants and the acid dissociation constants of aroylpyrazolones were obtained when TOPO was not added. The metal chelates of aroylpyrazolones react with TOPO to form MA3L and MA3L2 types of adducts in the synergic extractions. Obvious steric hindrances of the terminal substituents at ortho- position of 4-aroyl group of the ligands on the adduct formation reaction were observed by the comparison of adduct formation constants.

Investigations of binding sites and stability of complexes formed in ternary Cu(II)/adenosine or cytidine/putrescine systems

In the adenosine-putrescine (1,4-diaminobutane) system, noncovalent interaction between bioligands was found to occur. The equilibrium constant of the adduct formation reaction is equal to log K = 1.51. The ligand-ligand interaction is not observed to occur in the cytidine/putrescine system. On the basis of computer analysis of potentiometric titration data for ternary systems: Cu(II)/adenosine (or cytidine)/putrescine, the stability constants of the complexes were determined and their distribution was presented. It was found that in the cytidine-containing systems, mixed-ligand complexes are not formed. Spectral studies indicate characteristic differences in the mode of coordination in the adenosine ternary systems relative to binary systems. A presence of putrescine contributes to the broadening (relative to the Cu(II)/Ado binary system) of pH range for the coordination dichotomy to occur. Differences in the coordination mode between the synthesized solid complexes and complexes in solution have been identified. Likewise in solution, cytidine does not form solid mixed-ligand complexes with Cu(II) and putrescine.

Oxidative coupling of mithramycin and hydroquinone catalyzed by copper oxidases and benzoquinone. Implications for the mechanism of action of aureolic acid antibiotics

The copper oxidases human ceruloplasmin and Polyporous anceps laccase catalyze the oxidative coupling of mithramycin ( 1) and its aglycone chromomycinone ( 2) with p-hydroquinone to form new mithramycin-hydroquinone ( 3) and chromomycinone-hydroquinone adducts ( 4), respectively. Similar adducts could be formed by the nonenzymatic mimic of this reaction using benzoquinone and these aureolic acids in buffer solutions. FABMS of 3 indicated that the hydroquinone moiety was attached to the aureolic acid aglycone. Acid hydrolysis of 3 yielded a compound with the same chromatographic and spectroscopic characteristics as 4. Structure elucidation of 4 by NMR and MS revealed that the hydroquinone was attached to the C-5 position of the aglycone. NMR evidence indicated that 4 consisted of a mixture of ortho-substituted biphenyl rotamers. The mechanism of the copper oxidase catalyzed adduct formation reaction is presumed to involve radical formation through hydrogen removal at the 8-phenolic position, radical isomerization, and coupling with semiquinone radical also formed during enzymatic and nonenzymatic incubations. Identification of the covalent-hydroquinone adduct provides evidence that aureolic acid antibiotics can be metabolically converted to reactive radical intermediates, and it establishes the C-5 position of aureolic acid as an enzymatically reactive site. Unlike mithramycin, the mithramycin-hydroquinone adduct was inactive in the in vivo P388 leukemic antitumor test system.

Nickel(II) chelates of unsaturated aroylhydrazones and their reactions with pyridines

The reactions of nickel(II) acetate with cinnamaldehyde- and benzalacetone- aroylhydrazones( 2) (R′ = H or CH 3) afforded green octahedral paramagnetic NiL 2·2H 2O chelates, where L refers to the mononegative bidentate ligand. Upon dehydration of these chelates, brown and yellow square-planar diamagnetic complexes (α-series) were isolated, respectively. The in situ reactions of cinnamaldehyde and aroylhydrazines in the presence of nickel(II) acetate gave diamagnetic orange complexes with the planar arrangement around the nickel(II) ion (β-series). Based on the IR and IV spectral data trans-geometry was assigned for the brown and yellow α-series and cis-geometry for the orange β-series. Both the brown or yellow and orange forms behave differently towards pyridine. Their crystallization from pyridine solutions led to the isolation of stable bis- and tetrakis- (pyridine) adducts, respectively. The stability constants and the thermodynamic parameters for the adduct formation reactions of the orange NiL 2 chelates with py, 3-Mepy and 4-Mepy have been evaluated.

陰イオン交換膜に担持された亜硫酸水素イオンによるホルムアルデヒトの促進輸送

Formaldehyde was transported efficiently across hydrogensulfite ion form anion-exchange membrane via the adduct formation reaction. The transport of formaldehyde was facilitated but onlywhen the concentration of formaldehyde in the source phase solution was low. The ion-exchange capacity of the membrane was saturated by formaldehyde distributed as its adduct in a low source phase concentration because the adduct formation constant was high. The transport of formaldehyde can be further facilitated and formaldehyde was transported against the concentration gradient with the counter-transport of hydrogensulfite ion when hydrogensulfite salt was added to the receiving phase.

Properties of trifluoromethylgermanes. Adduct formation and substitution reactions of (CF 3) nGeX 4− n ( n = 2–4) with NH 3

Crystalline adducts of compositions (CF 3) 4Ge· nRNH 2 (R = H: n = 2, 3; R = CH 3: n = 1, 2 with dissociation vapour pressures at 22°C of 70 (R = H) and 75 mbar (R = CH 3) have been isolated. From their Raman spectra both NH 3 adducts are judged to have a cis-configurated octahedral coordination at the germanium atom. Reaction of (CF 3) 3Gel with NH 3 yielded the digermazane [(CF 3) 3Ge] 2NH whereas the cyclic trimers [(CF 3) 2GeNR] 3 (R = H, CH 3) were obtained from (CF 3) 2GeI 2 and RNH 2. IR spectra show that NH 3 and [(CF 3) 3Ge] 2NH undergo equilibration to give (CF 3) 3GeNH 2 in the gas phase, with simultaneous formation of a solid phase with the composition (CF 3) 3GeNH 2·2NH 3. Addition of trimethyl- or triethyl-amine to [(CF 3) 3Ge] 2NH yields solid 1:1 adducts. The vibration spectra of [(CF 3) 3Ge] 2NH, (CF 3) 3GeNH 2 and of the NH 3 adducts of (CF 3) 4Ge and of their deuterated analogues have been analyzed. A GeNGe bond angle of 130° was deduced for [(CF 3) 3Ge] 2NH from model force constant calculations.

Chemical reactivity of iron atoms near room temperature

The reactivity of ground state iron atoms with respect to atom transfer and adduct formation reactions with a variety of simple molecules in Ar buffer gas near room temperature has been investigated. Iron atoms are produced by visible multiphoton dissociation of iron pentacarbonyl or ferrocene, and their removal by added gases under pseudo-first-order conditions is monitored by resonance fluorescence excitation at variable time delay following the photolysis pulse. Upper limits for second-order rate constants for reaction of ground state iron atoms with O2, CO, H2O, (CH3)2O, C2H2, C2H4, N2O, C2H4O, and CF3Cl at room temperature and 100 Torr total pressure are estimated to be in the range (2–10)× 10−15 cm3 molecule−1 s−1, which corresponds to reaction probabilities of less than ≂10−5 per hard sphere collision. Pseudo-second-order rate constants in the range (2–60)× 10−14 cm3 molecule−1 s−1 are found for 1:1 adduct formation reactions of ground state iron atoms with C6H6, 1,3-butadiene, NH3, and NO. The formation of such complexes at room temperature implies that the binding energies are greater than ≂7 kcal mol−1. For the complex FeNH3, the kinetic data allow measurements of dissociation equilibrium constants at 278.5 and 295 K, from which a binding energy ΔH°0 = 7.5 ± 1 kcal mol−1 is derived. Measurements of the dependence of the pseudo-second-order rate constant for formation of FeNO on the pressure of Ar buffer gas at 296 K allow estimates to be made of the limiting low- and high-pressure recombination rate constants: k0 =2.3×10−32 cm6 molecule−2 s−1 and k∞=1×10−12 cm3 molecule−1 s−1. Comparisons are made between the present results which indicate a remarkably low reactivity for iron atoms, and previously reported results for reactions of iron atoms in low temperature matrices and gas phase reactions of other transition metal atoms. An interpretation of our results is given in terms of schematic potential energy curves which are based on the results of previous ab initio calculations for the complex FeCO. The qualitative features of these curves are consistent with low reactivity of ground state iron atoms with respect to adduct formation due to repulsive ground state interactions and low probabilities for transitions from repulsive to attractive potential surfaces.

Spectroscopic and kinetic characterization of nonenzymic and aldose reductase mediated covalent NADP-glycolaldehyde adduct formation

Reaction of glycolaldehyde with the binary E-NADP complex of bovine kidney aldose reductase (ALR2) produces an enzyme-bound chromophore whose absorbance (lambd max 341 nm) and fluorescence (lambda ex max 341 nm; lambda emit max 421 nm) properties are distinct from those of NADPH or E.NADPH yet are consistent with the proposed covalent adduct structure [1,4-dihydro-4-(1-hydroxy-2-oxoethyl)nicotinamide adenine dinucleotide phosphate]. The kinetics of adduct formation, both in solution and at the enzyme active site, support a mechanism involving rate-determining enolization of glycolaldehyde at high [NADP+] or [E.NADP]. At low [NADP+] or [E.NADP] the reaction is second-order overall, but the ALR2-mediated reaction displays saturation by glycolaldehyde due to competition of the aldehyde (plus hydrate) and enol for E.NADP. Measurement of the pre-steady-state burst of E-adduct formation confirms that glycolaldehyde enol is the reactive species and gives a value of 1.3 x 10(-6) for Kenol = [enol]/[( aldehyde] + [hydrate]), similar to that determined by trapping the enol with I3-. At the ALR2 active site, the rate of adduct formation is enhanced 79,000-fold and the adduct is stabilized greater than or equal to 13,000-fold relative to the reaction with NADP+ in solution. A portion of this enhancement is ascribed to specific interaction of NADP+ with the enzyme since the 3-acetylpyridine analogue, (AP)ADP+, gives values that are 15-200-fold lower. Additional evidence for strong interaction of ALR2 with both NADP+ and NADPH is reported. Yet, because dissociation of adduct is slow, catalysis of the overall adduct formation reaction by ALR2 is less than or equal to 67-fold.

Nuclear magnetic resonance studies and structural investigations of the chemistry of organotin compounds: Part I. 119Sn NMR studies of the pyrazine adducts of some organotin compounds

A procedure is described for the analysis of the concentration dependence of NMR chemical shift data on the chemical equilibria present in solution. This procedure has been used to study the equilibrium between SnMe 3Cl and 4-methylpyridine in benzene, and the values obtained for the thermodynamic parameters are in good agreement with those previously determined by a calorimetric method. The equilibria of the adduct formation reactions of SnPh 2Cl 2, SnPh 2Br 2 and SnPh 2I 2 with pyrazine in chloroform and acetonitrile have also been investigated. In chloroform solution, both 1:1 and 1:2 (M:L) adducts are formed, whereas only 1:1 adducts are formed in acetonitrile under the experimental conditions used. For all three organotin compounds the interactions are relatively weak. The Lewis acidity of the SnPh 2X 2 organotin species decreases in the order Cl > Br > I.

Steric effect of ortho-substituents of 1-phenyl-3-methyl-4-aroyl-5-pyrazolones on the synergic extraction of lutetium with trioctylphosphine oxide

The substituent effect of ortho-substituted 4-aroyl derivatives of 1-phenyl-3-methyl-5-pyrazolones (HA) on the adduct formation reaction between their lutetium chelates and a neutral ligand, trioctylphosphine oxide (TOPO, L), in benzene was studied using a liquid-liquid extraction system. The lutetium 4-aroyl-5-pyrazolonates react with TOPO to form LuA 3L and LuA 3L 2 types of adducts. An obvious steric hindrance of the terminal group on the adduct formation reaction was observed. Linear relationships between the acid dissociation constant of the ortho-substituted 4-aroyl-5-pyrazolone derivatives and those of the corresponding benzoic acids, between the extraction constants of lutetium and the acid dissociation constants of pyrazolones and between the adduct formation constants of TOPO and the acid dissociation constants of pyrazolones could be obtained.

Oxidative Addition and Adduct Formation Reaction of Carbonyl Compounds of Rhodium(I)

Oxidative Addition and Adduct Formation Reaction of Carbonyl Compounds of Rhodium(I)

The extraction of iron(III) from aqueous sulphate solutions by primene sulphate

A study of the extraction of iron(III) from aqueous sulphate media by the primary amine Primene 81R at 50°C has been made. The compound extracted from the organic phase with Primene 81R sulphate in kerosene has been isolated and recrystallized from a methanol-acetone mixture and has been shown to have the stoichiometric formula 3(RNH 3) 2SO 4·(Fe(OH)SO 4) 2 represents the alkyl groups associated with the amine. It has been shown that the extraction of iron(III) occurs by an adduct formation reaction between primary amine sulphate molecules and the species IFe(OH)SO 4I 2 from the aqueous phase. On the basis of the experimental data and spectral studies a dimeric structure is suggested for the extracted complex.

Reactions of the molybdenum(II) dicarbonyl complexes with mercury(II) halides and pseudohalides

The reactions of the molybdenum(II) dicarbonyl complexes, [MoBr(π-allyl)(CO) 2(L) 2] (L = CH 3CN, py) and (MoBr(π-allyl)(CO) 2(L,L)] (L,L = bipy, phen, dppe) with HgX 2 (X = Cl, CN, SCN) give several new complexes via a displacement reaction involving Br or/and L ligands or a simple adduct formation reaction.

Reactivity of metal chelates of sulphur containing ligands towards Lewis bases. Part III. Reaction of bis(1,2-dimethyl-and 1-phenyl-1,2-ethanediylidene)bis(S-methylhydrazinecarbodithioate)NN′SS′(−2)dizinc(II) with pyridines

The reaction of the dimeric zinc(II) chelates of the type I (R 1 = R 2 = CH 3, R 1 = H, R 2 = Ph) with pyridine, 2-methylpyridine, 3-methylpyridine and 4-methylpyridine afforded the monomeric monobase adducts. The isolated adducts were characterized by their electronic and 1H NMR spectra, and a five coordinate square pyramidal structure was tentatively assigned for these adducts. The adduct formation reaction was followed spectrophotometrically and the reaction kinetics were studied using a stopped flow technique. From the available kinetic data, as well as the measured activated parameters (Δ H #, Δ S #), a mechanism for the adduct formation reaction is proposed.

Studies on synergic extraction of uranium/VI/ by combination of 8-hydroxyquinoline and neutral donors

Extraction of U/VI/ by mixtures of 8-hydroxy quinoline /Oxine/ and neutral donors was studied from 0.1M NaCl at a pH ∼4.5. The presence of a neutral donor enhanced the extraction of U/VI/ and the species responsible for synergism was established to be 1∶1 adduct UO2Ox2S. From the data, the equilibrium constants for the adduct formation reaction were calculated and was found to be the lowest with TBP and the highest with TOPO.

Growth and characterization of Ga1−xInxAs by low pressure metalorganic chemical vapor deposition

Conditions for growth at 550°C of high structural quality GaInAs by LPMOCVD are presented. The sensitivity of compositional grading to changes in the V/III molar ratio, growth rate and inclusion of InP buffer layers is discussed. Crystalline uniformity is indicated by double crystal x-ray rocking curves with FWHM (GaInAs) = 0.017°. By careful control of the V/III molar ratio, epitaxial GaInAs/InP heterostructures with δa/a ≤ 10−4 can be grown. Quantitative data for the TEIn-AsH3 elimination reaction rate is presented. The composition of Ga1−xInxAs which is expected in the presence of this reaction is calculated; evaluation of the corresponding rate constant shows that the adduct formation reaction proceeds at a modest but detectable rate. The problems associated with the purity of electronic grade triethylindium (TEIn) are addressed. Impurities in commercial TEIn have been determined by low resolution mass spectroscopy.

Adduct formation and exchange reactions of DI (tertiary aminophosphine) with PF5. Preparation of F2P[B10H10C2]PF2 and the novel [Me2NP(B10H10C2)PNMe2] (PF6)2

Abstract Phosphorus pentafluoride reacts with the di(tertiary aminophosphines) of the type RR′P[B 10 H 10 C 2 ]PR″R‴[RR′C 6 H 5 or NMe 2 ,R″R‴NMe 2 : RR″NMe 2 , R′R‴F: RR′C 6 H 5 ,R″NMe 2 ,R‴F] to give adducts containing P(III)->P(V) bonds. Thermal decomposition of the adducts leads to products where an amino group is exchanged by fluorine. The adduct Me 2 N(F)P[B 10 H 10 C 2 ]P(F)NMe 2 .2PF 5 in CH 3 CN solution exists in the ionic form [Me 2 NP(B 10 H 10 C 2 )PNMe 2 ] (PF 6 ) 2 containing dicoordinate phosphorus. Thermal decomposition of this adduct gives the novel F 2 P [B 10 H 10 C 2 ] PF 2 .

Spectroscopic study of adduct-formation reactions in several copper(II) porphyrins

Spectroscopic study of adduct-formation reactions in several copper(II) porphyrins

Synthesis and structure of (.eta.-C5H5)W(PPh3)(CO)(CSPh): transformation of a thiocarbonyl ligand into a carbyne ligand

The arylation reaction (eta-C/sub 5/H/sub 5/)W(PPh/sub 3/)(CO)(CS)I + LiPh ..-->.. (eta-C/sub 5/H/sub 5/)W(PPh/sub 3/)(CO)(CSPh) + LiI (5) reduces the multiple bonding in the terminal CS ligand of (eta-C/sub 5/H/sub 5/)W(PPh/sub 3/)(CO)(CS)I to a C-S single bond in the carbyne product. The previously reported alkylation (Ph/sub 2/PCH/sub 2/CH/sub 2/PPh/sub 2/)/sub 2/W(CO)(CS) + MeOSO/sub 2/F ..-->.. (Ph/sub 2/PCH/sub 2/CH/sub 2/PPh/sub 2/)/sub 2/W(CO)(CSMe)/sup +/SO/sub 3/F/sup -/ (1), and Lewis adduct formation reactions of terminal CS groups in electron-rich complexes presumably also yield CSR carbyne complexes. These results suggest that similar adducts of terminal CO ligands could be reasonable intermediates in catalytic reactions of carbon monoxide which lead to the cleavage of the carbon-oxygen triple bond. A single crystal of (eta-C/sub 5/H/sub 5/)W(PPh/sub 3/)(CO)(CSPh) approx. 0.2 x 0.15 x 0.4 mm was chosen for the x-ray diffraction study. The average distance from the tungsten to the cyclopentadienyl carbon atoms is 2.366 A. Data were given for the other ligands. 1 figure. (DP)

Thermodynamics of 1:1 Adduct-formation of Bis(trifluoroacetyl-acetonato)copper(II) with Lewis Bases

Abstract Formation constants and thermodynamic parameters for the 1: 1 adduct-formation reactions of bis(trifluoroacetylacetonato)copper(II), Cu(tfac)2, with alkylamines, α-picoline, 2,6-lutidine, and THF have been determined spectrophotometrically. The ΔH°–ΔS° plots for primary and secondary alkylamines gave a linear relationship for the thermodynamic parameters of the Cu(tfac)2-heterocyclic base systems. The plots for the 2,6-lutidine, THF and tertiary alkylamine systems have been found consistent with a correlation between ΔH° and ΔS° values for bis(acetylacetonato)copper(II)–heterocyclic base systems. It has been subsequently deduced that the 1: 1 adducts of Cu(tfac)2 with Lewis bases possess a square-pyramidal structure on the basis of the ESR data for the 63Cu(tfac)2–Lewis base systems.