Structure of salts of substituted 2-alkylthiotetrahydropyrimidines

The structure and ring-chain tautomerism of 2-alkylthio-3,4,6,6-tetramethyl-4-hydroxy-3,4,5,6-tetrahydropyrimidine hydrohalides (Alk = CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, iso-C₄H₉, CH₂C₆H₅ Hal = Cl, Br, I) were analyzed by means of UV, IR, and PMR spectroscopy. It is shown that the cations of the salts in the crystalline state and in solutions exist primarily in the cyclic form.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 695–698, May, 1982.     

Kinetics and mechanism of acid hydrolysis of peroxyketals

The kinetics of hydrolysis of aliphatic ketone di-tert-butylperoxyketals R¹R²C=O, R¹, R²=CH₃, CH₃; CH₃, C₂H₅; CH₃, n-C₃H₇; CH₃, n-C₆H₁₃; CH₃, i-C₅H₁₀; CH₃, i-C₄H₉; C₂H₅, i-C₃H₇; n-C₄H₉, n-C₄H₉; CH₃, C₆H₅-CH₂, in dioxane in the presence of H₂SO₄ were investigated by IR spectroscopy. It was found that the reaction is reversible and takes place according to the equation R¹R²C· (OOC(CH₃)₃)₂ + H₂O;_H+ R¹R²C=O + 2HOOC(CH₃)₃. The proposed mechanism of hydrolysis includes the fast, quasiequilibrium formation of protonated peroxyketal and subsequent formation of the alkylperoxycarbenium ion. A three-parameter correlation equation is proposed for describing the initial rates of hydrolysis of R¹R²C(oo-t-Bu)₂ peroxyketals.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2501–2506, November, 1990.     

Reactivity of peroxy radicals in the reaction with nickel bis(diisopropyldithiophosphate)

The rate constants of the reaction of peroxy radicals C₆H₅CH(00^.)R with nickel bis(diisopropyldithiophosphate) change as function of the nature of the substituent R in the order (75°C) H > CH₃ > iso-C₃H₇ > n-C₄H₉ > tert-C₄H₉; the order conforms with the decreasing order of Charton's steric constants of the substituents R.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 28, No. 3, pp. 236–238, May–June, 1992.     

Dealkylation of alkylcobalt complexes by the mercury(II) electrophile

The dealkylation of a variety of RCo(BDMBg)⁺ complexes by Hg²⁺ is discussed. (The ligand BDMBg^- is formed by the condensation of two moles of 2,3-butanedionemonoxime with one mole of 1,3-propanediamine or 1,2-ethanediamine.) The products of the dealkylation reaction are Co^III(BDMBg)(H₂O)²⁺₂ and RHg⁺. All reactions are first order in the [Hg²⁺]. The second order rate constants (k₂) vary from 5.9 M^-1 sec^-1 (R = CH₃) to 5.7 x 10^-3M^-1 sec^-1 (R = n-C₃H₇). The relative rates for R are: CH₃ ? C₂H₅ τ C₆H₅CH₂ τ n-C₄H₉ ? n-C₃H₇. This order and other evidence are indicative of an S_E2 mechanism with an attack by Hg²⁺ on the carbon bonded to the cobalt.     

Reactions of alkylcobalt complexes containing a tetradentate nitrogen-donating ligand

The reactions of RCo(BDM1,3pn)(H₂O) with light, heat, acids, electrophiles and nucleophiles were studied. (HBDM1,3pn is a mononegative, tetradentate dioxime-diimine ligand formed by condensing 2,3-butanedionemonoxime with 1,3-propanediamine in a 2/1 molar ratio; R = CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, and C₆H₃CH_2-) Pyrolysis and photolysis of the alkyl complexes result in a cobalt(II) complex (anaerobic conditions) along with alkenes and alkanes. The major organic products from solid state pyrolysis at 200°C or photolysis in water are CH₄ (R = CH₃), C₂H₄ (R = C₂H₅), C₃H₆ (R = n-C₃H₇), C₄H₈ (R = n-C₄H₉) and (C₆H₅CH₂)₂ (R = C₆H₅CH₂). No alkyl—cobalt bond cleavage occurs with acids or bases in most cases. Two exceptions are the reactions with 3 M HNO₃ at 25°C and with 1 M NaOH at 52°C. Electrophiles like I₂ cleave the alkyl—cobalt bond forming RI and Co^III (BDM1,3pn)I₂. Nucleophilic reagents (N^-) displace the H₂O trans to the alkyl group to form RCo(BDM1,3pn)(N), but do not dealkylate the alkyl complex under the reaction conditions studied.     

Versatile rare earth hexanuclear clusters for the design and synthesis of highly-connected ftw-MOFs

A series of highly porous MOFs were deliberately targeted to contain a 12-connected rare earth hexanuclear cluster and quadrangular tetracarboxylate ligands. The resultant MOFs have an underlying topology of ftw, and are thus (4,12)-c ftw-MOFs. This targeted rare earth ftw-MOF platform offers the potential to assess the effect of pore functionality and size, via ligand functionalization and/or expansion, on the adsorption properties of relevant gases. Examination of the gas adsorption properties of these compounds showed that the ftw-MOF-2 analogues, constructed from rigid ligands with a phenyl, naphthyl, or anthracene core exhibited a relatively high degree of porosity. The specific surface areas and pore volumes of these analogs are amongst the highest reported for RE-based MOFs. Further studies revealed that the Y-ftw-MOF-2 shows promise as a storage medium for methane (CH₄) at high pressures. Furthermore, Y-ftw-MOF-2 shows potential as a separation agent for the selective removal of normal butane (n-C₄H₁₀) and propane (C₃H₈) from natural gas (NG) as well as interesting properties for the selective separation of n-C₄H₁₀ from C₃H₈ or isobutane (iso-C₄H₁₀).     

Effect of N-alkyl and N-aralkyl substituents on nucleophilic substitution in the benzimidazole series

It is shown in the case of the Chichibabin reaction and exchange of chlorine in 2-chlorobenzimidazoles by a piperidine residue that N-alkyl and N-aralkyl groups are arranged in the following order with respect to their effect on the rate of the process (in the order of decreasing rates): CH₃>C₆H₅CH₂, C₂H₅>iso-C₃H₇, (C₆H₅)₂CH>n-C₉H₁₉>tert-C₄H₉. The overall decrease in the rate on passing to compounds with branched N-substituents is low. It follows from this that steric hindrance to nucleophilic substitution in the 2 position is only of small significance.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1120–1125, August, 1977.     

Studies on organophosphorus compounds XLVIII Synthesis of Dithioesters from P,S-Containing Reagents and Carboxylic Acids and Their Derivatives

2,4-Bismethylthio-1,3,2,4-dithiadiphosphetane 2,4- disulfide, IIa, is prepared from 0,0-dimethyldithiophosphoric acid, Ia, and P₄S₁₀ at 160°C. 2,4-Bis(4-phenoxyphenyl)-1,3,2,4- dithiadiphsophetane 2,4-disulfide, IIc, and 2,4-bis(4-phenylthiolophenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, IId, are prepared at l60°C from P₄ S₁₀ and diphenylether and diphenylsulfides, respectively. Carboxylic acids RCOOH(R = CH₃ C₂H₅, n-C₃H₇, n-C₄H₉, C₆H₅CH₂, C₆H₈) react with compound Ia at 130°C to give the corresponding methyl dithioesters. Carboxylic acids RCOOH (R = C₆H₈-CH₂, C₆H₈) react with compound Ib at 200°C for 15 min to give the corresponding ethyl dithioesters, while low boiling acids (R = CH₃, C₂H₈, n-C₃H₇) yielded mixtures of the corresponding ethyl dithioester and ethyl carboxylate. Carboxylic acid chlorides RCOCl (R = ClCH₂, C₂H₅, t-C₄H₅ C₆H₅CH₂, C₆H₅, P-NO₂C₆H₄) react with compound IIa at 80°C to give the corresponding methyl dithioesters in good yields. S-Substituted thioesters react with IIC at 85°C to give the corresponding dithioesters in good yields. Dihydro2(3H)-furanone, VI, and 5-methyl-2(3H)-furanone, VII, react with IIa at 80°C; to dihydro-2(3H)-thiophenethione, VIII and 2,2'-dithiobis(5-methyl thiophene),IX, respectively. Also XI reacts with IIa,IIc, and IId to give VIII in nearly quantitative yields.     

Formation Constant of Dialkyltin(IV)-N-(Alkyl)-2/3-mercaptoacetamide Systems

The thermodynamic formation constants of N-(alkyl)-2- and/or 3-mercaptoacetamides complexes with dimethyl-, diethyl-, and n-dibutyltin(IV) cations have been determined potentiometrically in a dioxane-water mixture (75% v/v) at 30 ± 0.1°C in μ = 0.1 M NaCl using the Irving-Rossotti method and refined by the least-squares method. The basicity of the ligands follows the order C₂H₅NHCOCH₂SH > n-C₃H₇NHCOCH₂SH > n-C₄H_gNHCOCH₂SH > C₂H₅NHCOCH₂CH₂SH > n-C₃H₇NHCOCH₂CH₂SH > n-C₄H_g- NHCOCH CH SH. For each ligand the stability order of dialkytin(IV) complexes decreases as follows: [Me₂Sn(IV)]²⁺ >[Et Sn(IV)]²⁺ > [n-Bu₂Sn(IV)]^2+. This order is consistent with the group electronegativities of [R₂Sn(IV)]²⁺ cations calculated from Sanderson's electronegativity scale.     

Hydrogen purification using a SAPO-34 membrane

A SAPO-34 membrane separated CO₂/H₂ and H₂/CH₄ mixtures at feed pressures up to 1.7 MPa. Strong CO₂ adsorption inhibited H₂ adsorption and decreased H₂ permeances significantly, especially at low temperatures, so that CO₂ preferentially permeated and CO₂/H₂ selectivities were higher at low temperatures. At 253 K, CO₂/H₂ separation selectivities were greater than 100 with CO₂ permeances of 3 × 10⁻⁸ mol m⁻² s⁻¹ Pa⁻¹. The CO₂/H₂ separation exceeded the upper bounds (selectivity–permeability plot) for polymer membranes. The SAPO-34 membrane separated H₂ from CH₄ because CH₄ is close to the SAPO-34 pore size and has a lower diffusivity than H₂. The H₂/CH₄ separation selectivity had a small maximum with temperature, and decreased slightly with feed pressure and CH₄ feed concentration.     

Ligand effects on the Pt(II) → Pt(0) reduction of dichlorobis(tertiary phosphine)platinum(II) complexes: Correlations between electrochemical data,spectroscopic data,and electronic ligand parameters

Cyclic voltammetry has been employed to study the diffusive, irreversible platinum(II) → platinum(0) reduction of three sets of structurally related complexes: cis-[PtCl₂P{p-C₆H₄X}₃)₂] (X = H, CH₃, Cl, F, OCH₃, N(CH₃)₂); cis-[PtCl₂(PPh₂R)₂] (R = CH₃, n-C₃H₇, n-C₅H₁₁, n-C₆H₁₃, n-C₁₂H₂₅) and cis-[PtCl₂(PR₃)₂] (R = CH₃, C₂H₅, CH₂ch₂CN). Relationships between the peak potentials for the Pt(II) → Pt(0) reduction and thermodynamic parameters which measure the electronic properties of the ligands are shown to exist for complexes of P{p-C₆H₄X}₃ ligands, implying a thermodynamic origin for the sensitivity of the peak potentials to structural change. Complexes of both P{p-C₆H₄X}₃ and PPh₂R ligands show correlations between peak potentials for reduction and the ³¹P{¹H} NMR spectroscopic parameter, ¹J(¹⁹⁵Pt, ³¹P). Correlations with values of δ(³¹P) exist in both cases, but a correlation with the coordination chemical shift, Δδ(³¹P), exists for complexes of PPh₂R, and not for complexes of P{C₆H₄X}₃. Complexes of PR₃ ligands show no correlation between the peak potentials measured for the Pt(II) → Pt(0) reduction and electronic or spectroscopic parameters, except possibly ¹J(¹⁹⁵Pt, ³¹P).     

Diorganotin(IV) complexes of N-protected dipeptides

Eight new diorganotin(IV) complexes of general formula R₂Sn(DP)₂ and [R₂Sn(DP)]₂O (DP = anion of N-benzoyl-dl-alanylglycine; R = CH₃, C₂H₅, n-C₄H₉, n-C₈H₁₇) have been prepared and characterised by IR, and ^119mSn Mössbauer spectroscopy. However, only two complexes, (DP)₂Sn(n-C₄H₉)₂ and (DP)₂Sn(n-C₈H₁₇)₂ were sufficiently soluble for NMR (¹H and ¹³C) studies. The 2 : 1 complexes are monomeric with distorted trans-octahedral structures. The 1 : 1 complexes are dinuclear with Sn-O-Sn bridges and trigonal bipyramidal geometry about tin. In both cases the dipeptide acts as an O,O-bidentate ligand.     

Adsorption of natural gas and its whole components on adsorbents

Adsorption of each component of natural gas on adsorbent prepared from petroleum coke was studied. At 25 °C and 3.5 MPa, adsorption capacity of the components of natural gas are as follows: C₃H₈, H₂S(0.980) > CO₂(0.691) > C₂H₆(0.160) > CH₄(0.136) > N₂(0.096) (g/g). For natural gas, adsorption capacity is 145.2 (mL/mL) and delivery capacity is 105.7 (mL/mL). One equation between adsorption capacity and boiling point of adsorbed gas was firstly generalized. The adsorption capacity of different component like O₂, N₂, CH₄, C₂H₆, CO₂, H₂S on adsorbents were predicted using the equation. The results fit well with the experimental data. The equation has significance in predicting the adsorption capacity for any component of natural gas. Charge-discharge tests were conducted 10 times, the result indicates that natural gas has significantly worse reversibility in adsorption and desorption in the adsorbent than that of CH₄. The contents of the components after 10 charge-discharge show that the adsorption capacity drop of natural gas is due to the irreversible adsorption of heavy or polar components like C₃H₈, H₂S.     

Spektroskopische Untersuchungen an Trialkyl- und Triarylfluorgermanen

The RAMAN and IR spectra (400–4000 cm^?1) of (CH₃)₃GeF, (C₂H₅)₃GeF, (n-C₃H₇)₃GeF, (n-C₄H₉)₃GeF in the solid, liquid and gaseous state, and of (C₆H₅)₃GeF in the solid and dissolved state are recorded and the frequencies almost completely assigned. The spectra show in the region 500–700 cm^?1 a relatively high shift of the frequencies, due to intermolecular interaction.     

The role of chelate substituent steric effects in reactions between hydroperoxyl radicals and copper bis(salicylalalkyliminates)

Rate constants for the reactions between HOO radicals and [2-(R-N= CH)C₆H₄O]₂Cu decreased according to the nature of the R substituent in the order (70°C): CH₃ > n-C₄H₉ > iso-C₃H₇ > cyclo-C₆H₁₁ > tert-C₄H₉; this followed the same sequence as the Charton steric constants of the R substituents.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 29, No. 1, pp. 70–73, January–February, 1993.The authors would like to express their gratitude to the Ukrainian Basic Reaearch Fund for financing the current work.     

Characterization of five [C4H7O]+ Ion structures. Fragmentation of the 2-pentanone molecular ion

The [C₄H₇0]⁺ ions [CH₂?CH? C(?OH)CH₃]⁺ (1), [CH₃CH?CH? C(?OH)H]⁺ (2), [CH₂?C(CH₃)C(?OH)H]⁺ (3), [Ch₃CH₂CH₂C?O]⁺ (4) and [(CH₃)₂CHC?O]⁺ (5) have been characterized by their collision-induced dissociation (CID) mass spectra and charge stripping mass spectra. The ions 1–3 were prepared by gas phase protonation of the relevant carbonyl compounds while 4 and 5 were prepared by dissociative electron impact ionization of the appropriate carbonyl compounds. Only 2 and 3 give similar spectra and are difficult to distinguish from each other; the remaining ions can be readily characterized by either their CID mass spectra or their charge stripping mass spectra. The 2-pentanone molecular ion fragments by loss of the C(1) methyl and the C(5) methyl in the ratio 60:40 for metastable ions; at higher internal energies loss of the C(1) methyl becomes more favoured. Metastable ion characteristics, CID mass spectra and charge stripping mass spectra all show that loss of the C(1) methyl leads to formation of the acyl ion 4, while loss of the C(5) methyl leads to formation of protonated vinyl methyl ketone (1). These results are in agreement with the previously proposed potential energy diagram for the [C₅H₁₀O]⁺˙ system.     

Chlor(methyl)(organylthio)gallane,die ersten vertreter dieser gallium(III)-verbindungen

The reactions between dichloromethylgallane and the silyl sulfides (CH₃)₃SiSR (R = CH₃, C₂H₅, n-C₃H₇, i-C₃H₇, Ph and CH₂Ph) in benzene result in the formation of the hitherto unknown, extremely moisture-sensitive chloro(methyl)(organylthio)gallanes. Reactions of these thiogallanes with the donor compounds N(CH₃)₃ and O(CH₃)₂ are reported. Spectra as well as some physical and chemical properties of the new compounds are given.     

DIPHENYLANTIMONY(III) DERIVATIVES OF ALKYL XANTHATES

Abstract

A few diorganoantimony(III) derivatives, Ph₂SbS₂COR, have been prepared by the interaction of Ph₂SbCl/Ph₂SbOAc with ROCS₂ K (where R ? CH₃, C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉, i-C₄H₉). These derivatives have been characterized by elemental analyses, molecular weight determinations, IR and NMR (¹H and ¹³C) spectral data. The monodentate nature of the ligand in these derivatives has been proposed.     

An investigation of the decomposition of the common intermediate ions produced by electron impact. IV—[C6H5CO]+ ions from several alkyl benzoates

The decomposition of the [C₆H₅CO]⁺ ions produced from eight alkyl benzoates by electron impact has been studied. By calculating the heat of formation of [C₆H₅CO]⁺ ions from the appearance potential value, it is shown that the ions from C₆H₅COOR when R?H, CH₃, C₂H₅ have some excess energy, and those where R = n-C₃H₇, iso-C₃H₇, n-C₄H₉, iso-C₄H₉, iso-C₅H₁₁ are produced with more excess energy. It is also shown that by taking this excess energy into account, there is a linear relationship between the heat of formation of the activated complex produced in the reaction [C₆H₅CO]⁺→[C₆H₅]⁺ + CO and the vibrational degree of freedom of the neutral fragment ? OR.     

Fluoraustauschreaktionen an Metalltrifluorphosphin-Komplexen. IX. Zum Reaktionsverhalten von Tetrakis(trifluorphosphin)nickel(0) gegenüber Alkyl(trimethylsilyl)aminen und -amiden

Fluorine Exchange in Trifluorophosphine Metal Complexes. IX¹. (Reactions of Tetrakis(trifluorophosphine)nickel(0) with Alkyl(trimethylsilyl)amines and Amides²) Alkylaminodifluorophosphine complexes Ni(PF₃)_4-n(PF₂NHR)_n (n = 1, 2, 3) 8–11 and Me₃SiF are obtained, if alkyl(trimethylsilyl)amines NHR(SiMe₃) (R?CH₃ and n-C₄H₉) are reacted with Ni(PF₃)₄ ( 1 ). The mechanism of these peripheric reactions is discussed by assuming a four centered type intermediate. However reactions of 1 with the lithium amides LiNR(SiMe₃) (R = CH₃, C₂H₅, n-C₄H₉, and C₆H₅) yield LiF and the difluorotrimethylsilylaminophosphine complexes Ni(PF₃)_4-n[PF₂NR(SiMe₃)]_n (n = 1, 3, 4) 12–18 .