Mono-Protected Diamines. N-tert-Butoxycarbonyl-α,ω-Alkanediamines from α,ω-Alkanediamines

We wish to report a convenient pathway to N-tert-butoxycarbonyl-α,ω-alkanediamines 2a-e [H₂N(CH₂)χNHBOC; χ=2, 3, 4, 5 and 6; (75–90% yields)] by treatment of the corresponding α,ω-alkanediamine with di-tert-butyl dicarbonate in dioxane as the solvent. Only small amounts of the bis-substituted N.N′-tert-butoxycarbonyl-α,ω-alkanediamines 3a-e were formed (2–9%) which were easily removed by an aqueous workup. The α,ω-alkane-aza-diamine 4 was also mono-protected (62% yield of 5) by the same methodology.     

Synthesis of N,N'-Disubstituted α,ω-Alkanediamines,Precursors of Linear bisDithiocarbamates

Linear bis dithiocarbamates are conveniently obtained from symmetrical disubstituted α,ω-alkanediamines whose preparation is reported.     

Study on Synthesis and Intercalation Behavior of Layered Zirconium Proline-N-methylphosphonate-phosphate

Zirconium proline-N-methylphosphonate-phosphate (α-ZPMPP) was prepared in the presence of HF for the first time. The α-ZPMPP sample is highly crystallized with interlayer distance of 1.52nm. The interlayer distance of complex of α-ZPMPP with n-butylamine (α-ZPMPP-BA) is in 0.45 nm larger than that of α-ZPMPP. The α-ZPMPP possesses different intercalation behavior of host-guest compound from α-ZP.     

Intercalation of Aminomethylcrowns into α-Zirconium Phosphate

The intercalation of (±)-2-aminomethylcrowns into -zirconium phosphate has been investigated by the batch method and followed by X-ray diffractometry. The reaction was dependent on the solvent, and 1-propanol was employed as a solvent. (±)-2-Aminomethyl-12-crown-4 and -15-crown-5 were taken up in two and three stages, respectively, while the uptake process of (±)-2-aminomethyl-18-crown-6 was complicated. Monolayers and bilayers of aminomethylcrowns might be formed when inserted into the interlayer space. ³¹P CPMAS-NMR and IR spectra of the intercalates suggest that the amino group is protonated by a proton of the phosphate group and/or proton transfer from the phosphate group to the amino group occurred.     

Intercalation of PM-19 into and in vitro Release of Anti-tumor Drug from Layered Double Hydroxide

Recently, controlled release ot drugs and gene delivery technology have received considerable attention due to their numerous advantages including prolonged duration of action of an active agent, improved efficacy, reduced toxicity and convenience compared to the conventional dosage forms. In this field typical systems are polymer delivery systems depending on the hydrolysis-induced degradation,     

Electrochemical oxidation of tetramethyl esters of α,α,ω,ω-alcaneteracarboxylic acids

Cyclization of esters of butane-1,1,4,4- and pentane-1,1,5,5-tetracarboxylic acids during electrolysis in methanol in the presence of Nal produces, with a yield of 95%, the esters of cyclobutane-1,1,2,2- and cyclopentane-1,1,2,2-tetracarboxylic acids. Under similar conditions, esters of the highest ,,,-alkanetetracarboxylic acids undergo iodation and hydroxymethylation due to electrical oxidation of methanol to formaldehyde. During electrolysis in methanol in the presence of NaOAc, the esters of ,,,-alkanetetracarboxylic acids undergo effective hydroxymethylation, followed by cyclization into substituted five- and six-member lactones, or tetrahydrofurans when structurally possible.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2332–2339, October, 1992.     

A facile synthesis of α,α,ω,ω-tetrahalo-α,ω-dicarboxylic esters

The synthesis of some α,α,ω,ω-tetrachloro and tetrabromo-derivatives of the hypolipidemic 3,3,14,14-tetramethylhexadecanedioic acid from α,ω-dihalo-esters, carbon tetrahalides and lithium diisopropyl amide has been described. Interaction of α,ω-dichloro esters with CBr₄ was shown to give the expected α,ω-dibromo-α,ω-dichloro compounds, but treatment of bis(l-methylethyl) 2,15-dibromo-3,3,14,14-tetramethylhexa-decanedioatewith CCl₄ was found to result in halogen exchange yielding the tetrachloro-diester as the major product.     

The rate of intramolecular end-to-end photodimerisation of α,ω-dianthrylpolystyrene in solution

To study the effect of molecular weight on the rate of the intramacromolecular end-to-end reaction of a flexible polymer, the intramolecular photodimerisation of α,ω-dianthrylpolystyrene has been carried out by successive illumination with a 337 nm pulsed nitrogen laser of a dilute solution of butanone at 30°C. The extent of dimerisation against the number of pulses (measured fluorometrically) was converted, based on several assumptions, to the apparent diffusion-controlled rate constants for polymer cyclisation. The rate constants for polymer cyclisation decrease in proportion to DP^−0·3 for the range of DP = 110–2600. The implications of this result in the chain dynamics of polymers are briefly discussed.     

Breaking of Symmetry of Solitons in the Ion-Radicals of α,ω-Disubstituted Polyenes

Quantum-chemical calculations in the AM1 approximation were made for the optimized geometry and also the electron and spin density distributions in the ion-radicals of ,-substituted polyenes [R—(CH=CH) _n —R]^±·. It was found that a soliton (of hole or electron type) with half-integral spin forms waves for the and components of the electron density, in contrast to the wave for the charges in the ions of polymethine dyes with a closed electron shell, containing a zero-spin soliton. The introduction of terminal groups of medium electron-donating power [—NH₂,—C(CN)₂] leads to the breaking of symmetry of the soliton at n2, whereas in unsubstituted polyenes the symmetrical geometry and symmetrical distribution of the electron and spin density are retained irrespective of the length of the conjugation chain.     

Some peculiarities of hydrosilylation of α,ω-divinyloligosilanes

The stability of Si-Si bonds in linear and cyclic permethyloligosilanes and in ,-divinyloligosilanes under conditions of hydrosilylation in the presence of the Speier's catalyst was studied. Polycarbosilanes containing silylene fragments in their backbone chains were prepared by the reaction of 1,4-bis(dimethylsilyl)benzene with ,-divinyloligosilanes. It was found that the structure of these polymers is disturbed due to the side reaction involving the cleavage of the Si-Si bond in vinyloligosilanes under the action of H₂PtCl₆.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2547–2549, October, 1996.     

Analysis of {α,ω-Dichloroalkane or α,ω-Dibromoalkane] + Benzene and α,ω-Dichloroalkane + Tetrachloromethane} Mixtures in Terms of Group Contributions

Abstract

Molar excess enthalpies, H ^E _m, at 298.15K and atmospheric pressure have been determined for three binary liquid mixtures [x{1,3-dichloropropane or 1,4-dichlorobutane and 1,6-dichlorohexane} + (1 - x) tetrachloromethane]. These experimental results along with the data available in the literature on molar excess Gibbs energies, G ^E _m, activity coefficients at infinite dilution, In γ^∞ _i , and molar excess enthalpies, H ^E _m, for α,ω-dihaloalkanes + benzene or + tetrachloromethane mixtures are examined on the basis of the DISQUAC group contribution model.     

Synthesis and characterization of α,ω-dichloro-polymethylphenylsilane

The synthesis of a functional polysilane, α,ω-dichloro-polymethylphenylsilane (α,ω-dichloro-PMPS), based on the Wurtz-type reductive coupling, has been considered. A study of some reaction parameters shows that both yield and molecular weight distribution of α,ω-dichloro-PMPS can be greatly influenced by the work-up conditions, reaction time, monomer concentration and temperature during the initiation of the polymerization. By varying the synthesis conditions, different ratios of high and low molecular weight fractions were obtained. Samples of different molecular weight were isolated by fractional precipitation of the crude polymers. The chlorine-end functionalization was confirmed by ²⁹Si NMR spectroscopy and the concentration of end-groups was quantitatively determined by elemental analysis of chlorine.     

Intercalation of N, N-dimethyl-1-phenylethylamine into α-Zirconium Phosphate

The intercalation and deintercalation of N, N-dimethyl-1-phenylethylamine (N,N-amine) into -zirconium phosphate was investigated by pH titration. N,N-amine was taken up easily in one step to give a new phaseZr(HPO⁴)(HPO₄·N,N-amine) · H₂O, which was characterized by X-ray diffractometry, IR spectroscopy, and thermal analysis. Therelease of N,N-amine from the solid was found to be irreversible due to structural changes in both the intercalation and deintercalation reactions.     

Intercalation of Cyclic Amines into α-Titanium Phosphate

The intercalation of some amines (aniline, benzylamine, cyclohexylamine,piperidine, pyridine, pyrazine and piperazine) into -titaniumphosphate, Ti(HPO₄)_2×H₂O,has been investigated by the batch method and/or by exposing the host to thevapour of the amines. The changes in the interlayer distance of the solidduring the intercalation process was followed by X-ray powder diffraction.The new intercalates were characterised by chemical and thermal analysis.Materials with a monolaminar and/or bilaminar arrangement of amine moleculesin the phosphate interlayer region are obtained depending on the nature ofthe amine. Due to steric hindrance, saturated phases are not obtained forall amines studied. The thermal decomposition of the intercalates (nitrogenatmosphere), takes place in three stages: dehydration, removal of amines andcondensation of the hydrogenphosphate to pyrophosphate groups.     

Effect of Temperature on The Solubility of α-Amino Acids and α,ω-Amino Acids in Water

The aqueous solubilities of glycine, dl-α-alanine (2-aminopropanoic acid), dl-α-aminobutyric acid (2-aminobutanoic acid), dl-α-norvaline (2-aminopentanoic acid), dl-α-norleucine (2-aminohexanoic acid), β-alanine (3-aminopropanoic acid), γ-aminobutyric acid (4-aminobutanoic acid), 5-aminovaleric acid (5-aminopentanoic acid), and 6-aminocaproic acid (6-aminohexanoic acid) were determined from 293.15 to 323.15 K at intervals of 5.00 K using the gravimetric method. The temperature dependence of the solubility of α-amino acids and α,ω-amino acids in water is well described by the van’t Hoff equation. Linear van’t Hoff plots were used to determine the differential enthalpy of solution. The results obtained are compared with reported values in literature and are discussed in terms of the position of the ionic groups in the hydrocarbon chain.