Synthesis and characterization of an aliphatic monoimide-bridged polysilsesquioxane by the sol–gel route

Based on differential scanning calorimetry data, it was shown that the reaction of (3-triethoxysilylpropyl)succinic anhydride and (3-amino)propyltriethoxysilane at 110 °C resulted in the formation of polyamic acid, whereas the thermal treatment at 220 °C led to the generation of an aliphatic monoimide-bridged polysilsesquioxane as proved by FT-IR. X-ray powder diffraction studies showed a prominent reflection at 2θ = 6.66° (d = 1.32 nm) revealing that a crystalline area is formed. ²⁹Si CP-MAS-NMR and ¹³C CP-TOSS-MAS-NMR measurements proved that no cleavage of the Si–C bond occurred, and a highly condensed material was obtained.     

Oxidation of aliphatic alcohols by triethylammonium chlorochromate in non-aqueous medium – A kinetic and mechanistic study

The oxidation of some aliphatic alcohols by triethylammonium chlorochromate (TriEACC) in dimethyl sulfoxide leads to the formation of the corresponding carbonyl compounds. The reaction is first order with respect to TriEACC. The reaction exhibited Michaelis–Menten type kinetics with respect to alcohol. The reaction is catalyzed by hydrogen ions. The hydrogen-ion dependence has the form: k_obs = a + b[H⁺]. The oxidation of [1,1-²H₂] ethanol (MeCD₂OH) exhibits a substantial primary kinetic isotope effect. Oxidation of aliphatic alcohol was studied in 19 different organic solvents. The solvent effect has been analysed using Kamlet’s and Swain’s multi-parametric equation. A suitable mechanism has been proposed.     

Synthesis of azamacrocyclic compounds by cyclocondensation of aliphatic α,ω-diamines with acetone

Cyclocondensation of 1,4-diaminobutane and 1,6-diaminohexane with acetone afforded the corresponding 18- and 22-membered trans-azamacrocyclic Curtis compounds in high yield, which contain two azomethine and amine nitrogen atoms. A complex mixture of the products formed containing less than 25% of 16-membered azamacrocyclic cis- and trans-isomers when reacting 1,3-diaminopropane with acetone.     

Synthesis and characterization of biodegradable aliphatic polyesters using dibutylmagnesium as initiator

Aliphatic polyesters were synthesized via the ring opening polymerization of the corresponding lactones initiated with dibutylmagnesium both in bulk and in solution. The resulting polymers were characterized by 1H, 13C NMR, GPC and XRD. The results indicated that dibutylmagnesium is an effective initiator for the ring opening polymerization of lactones.     

Interaction between hypocrellin and aliphatic amines

The interaction of hypocrellin, including hypocrellin A (HA) and hypocrellin B (HB), with aliphatic amines in deaerated solutions has been studied by ESR and nanosecond transient absorption spectra. In polar solvents, the acid-base interaction between hypocrellin and amines was observed without irradiation. The signals of semiquinone radical anions of hypocrellm and the spin-trapping adduct of α-phenyl-N-tertbutyl-ratrone (PNB) with the aminoalkyl radicals have been detected in photoinduced ESR studies. The transient absorption of excited triplet state of HA and semiquinone radical anion of HA have been observed in laser flash photolysis studies.     

Energetics of intramolecular hydrogen bonds and conformations of ω-diphenylphosphoryl- and ω-diphenylthiophosphoryl-substituted aliphatic alcohol molecules

A series of conformationally heterogeneous and energetically multilevel -diphenylphosphoryl- and -diphenylthiophosphoryl-substituted aliphatic alcohols, whose molecules are capable of five-, six-, and seven-membered ring closure due to the OH...O=P or OH...S=P intramolecular hydrogen bond (IHB), was studied by IR spectroscopy and molecular mechanics. The data obtained confirm the previous assumption that the energy of IHB (E _IHB) differs substantially from the difference of enthalpies of conformers with and without IHB (–H ), which is experimentally determined by the temperature dependence of the intensity of IR (OH) absorption bands. The measured –H values can be positive, zero, or negative at significant IHB effects, i.e., at high (OH) and E _IHB values.     

Automated determination of aliphatic primary amines in wastewater by simultaneous derivatization and headspace solid-phase microextraction followed by gas chromatography–tandem mass spectrometry

This paper presents a fully automated method for determining ten primary amines in wastewater at ng/L levels. The method is based on simultaneous derivatization with pentafluorobenzaldehyde (PFBAY) and headspace solid-phase microextraction (HS-SPME) followed by gas chromatography coupled to ion trap tandem mass spectrometry (GC–IT-MS–MS). The influence of main factors on the efficiency of derivatization and of HS-SPME is described in detail and optimized by a central composite design. For all species, the highest enrichment factors were achieved using a 85 μm polyacrylate (PA) fiber exposed in the headspace of stirred water samples (750 rpm) at pH 12, containing 360 g/L of NaCl, at 40 °C for 15 min. Under optimized conditions, the proposed method achieved detection limits ranging from 10 to 100 ng/L (except for cyclohexylamine). The optimized method was then used to determine the presence of primary amines in various types of wastewater samples, such as influent and effluent wastewater from municipal and industrial wastewater treatment plants (WWTPs) and a potable water treatment plant. Although the analysis of these samples revealed the presence of up to 1500 μg/L of certain primary amines in influent industrial wastewater, the concentration of these compounds in the effluent and in municipal and potable water was substantially lower, at low μg/L levels. The new derivatization–HS-SPME–GC–IT-MS–MS method is suitable for the fast, reliable and inexpensive determination of primary amines in wastewater in an automated procedure.     

Quantum chemical interpretation of reactivities of aliphatic amines and α-amino acids in acylation

Quantum chemical calculations of geometrical, electronic, and energy characteristics for aliphatic amines, ammonia, some α-amino acids, and 4-nitrophenyl benzoate (4-NPB) have been performed. By the QSPR method, it was found that the rate constants for the reactions of amino compounds specified with 4-NPB in water—propan-2-ol solvent mixture are linearly dependent on the contribution of the 2p_z-AO of nitrogen into the HOMO, as well as on the population of the 2p_z-AO of nitrogen. Different character of the dependencies for 6h-amino acids and aliphatic amines can be explained by their involvement into formation of solvato-complexes with different reactivity.     

Copper-catalyzed α-amination of aliphatic aldehydes

A highly efficient copper-catalyzed α-amination of aliphatic aldehydes for the synthesis of α-amino acetals using secondary amines with readily removable protecting groups as a nitrogen source was developed. This reaction can be operated under very mild conditions, affording the desired products in moderate to good yields.     

Acid-base thermochemistry of gaseous aliphatic α-aminoacids

Acid-base thermochemistry of isolated aliphatic amino acids (denoted AAA): glycine, alanine, valine, leucine, isoleucine and proline has been examined theoretically by quantum chemical computations at the G3MP2B3 level. Conformational analysis on neutral, protonated and deprotonated species has been used to identify the lowest energy conformers and to estimate the population of conformers expected to be present at thermal equilibrium at 298 K. Comparison of the G3MP2B3 theoretical proton affinities, PA, and ΔH(acid) with experimental results is shown to be correct if experimental thermochemistry is re-evaluated and adapted to the most recent acidity-basicity scales. From this point of view, a set of evaluated proton affinities of 887, 902, 915, 916, 919 and 941 kJ mol(-1), and a set of evaluated ΔH(acid) of 1433, 1430, 1423, 1423, 1422 and 1426 kJ mol(-1), is proposed for glycine, alanine, valine, leucine, isoleucine and proline, respectively. Correlations with structural parameters (Taft's σ(α) polarizability parameter and molecular size) suggest that polarizability of the side chain is the major origin of the increase in PA and decrease in ΔH(acid) along the homologous series glycine, alanine, valine and leucine/isoleucine. Heats of formation of gaseous species AAA, AAAH(+) and [AAA-H](-) were computed at the G3MP2B3 level. The present study provides previously unavailable Δ(f)H°(298) for the ionized species AAAH(+) and [AAA-H](-). Comparison with Benson's estimate, and correlation with molecular size, show that several experimental Δ(f)H°(298) values of neutral or gaseous AAA might be erroneous.     

CO cross-coupling of activated aryl and heteroaryl halides with aliphatic alcohols

A robust and general catalyst system facilitates the alkoxylation of activated heteroaryl halides with primary, secondary, and select tertiary alcohols without the need for an excess of either coupling partner. This catalyst system displays broad functional-group tolerance and excellent regioselectivity, and is insensitive to the order of reagent addition.     

Enantioselective addition of Et_2Zn to aldehydes catalyzed by chi-ral aliphatic β-amino alcohols

This paper describes the preparation of two new optically active aliphatic β-amino alcohols (R)-5,5-dimethyl-2-(dimethy-lamino)-1,1-diphenyl-1-hexanol (1a) and (S)-8,8-dimethyl-2-(dimethylamino)-1, 1-diphenyl-1-nonanol (1b). They were synthesized by methylation of the corresponding β-amino alcohols 2a and 2b. Compounds la and 1b catalyze the addition of diethylzinc to various aldehydes enantioselectively. The catalyst structure-enantioselectivity relationships were discussed.     

(NMCp)2TiCl2-catalyzed reduction of aliphatic,aromatic and α,β-unsaturated ketones by grignard reagent

Aliphatic, aromatic and α,β-unsaturated ketones were readily reduced to the corresponding secondary alcohols by iso-propylmagnesium bromide in the presence of a catalytic amount of bis(neomenthylcyclopentadienyl)titanium dichloride. A possible mechanism is discussed.     

The synthesis and thermal,optical and electrical properties of novel aromatic–aliphatic five- and six-membered thermotropic polyimides

Polymers have been prepared by the polycondensation of 4,4′-(butane-1,4-diylbis(oxy)) bis(butane-4,1-diyl) bis(4-aminobenzoate) and 5,10,15,20,25,30,35,40,45,50,55,60-dodecaoxatetrahexacontane-1,64-diyl bis(4-aminobenzoate) (PBBA 1200) with three dianhydrides based on naphthalene, perylene and phthalic moieties, respectively. This has resulted in five novel aliphatic–aromatic polyimides. The polyimides differed in aliphatic chain length and whether the imide ring was five- or six-membered. The chemical structure of the polyimides has been confirmed by ¹H NMR and FTIR spectroscopy and by elemental analysis. The optical and electrical properties of the polyimides have been studied using current–voltage measurements, and the effect of the polyimide structure on thermal and mesomorphic behaviour investigated by differential scanning calorimetry and polarising optical microscopy. Wide-angle X-ray diffraction at different temperatures was employed to confirm the structural properties of the polyimides. All the novel polyimides, with the sole exception of that obtained from PBBA1200 and 3,4,9,10-perylenetetracarboxylic dianhydride, showed liquid crystalline properties. As far as we are aware, this is the first time that six-membered polyimides exhibiting liquid crystalline properties have been reported.     

Ru/Me-BIPAM-catalyzed asymmetric addition of arylboronic acids to aliphatic aldehydes and α-ketoesters

A ruthenium-catalyzed asymmetric arylation of aliphatic aldehydes and α-ketoesters with arylboronic acids has been developed, giving chiral alkyl(aryl)methanols and α-hydroxy esters in good yields. The use of a chiral bidentate phosphoramidite ligand (Me-BIPAM) achieved excellent enantioselectivities.     

Simultaneous derivatization and air-assisted liquid–liquid microextraction of some aliphatic amines in different aqueous samples followed by gas chromatography-flame ionization detection

The paper presents a new method based on simultaneous derivatization and air-assisted liquid–liquid microextraction (AALLME) for the extraction and preconcentration of some aliphatic amines prior to gas chromatography-flame ionization detection (GC-FID). Primary aliphatic amines are derivatized and extracted simultaneously by a fast reaction with butylchloroformate (derivatization agent/extraction solvent) under mild conditions. The mixture of butylchloroformate and aqueous sample solution is rapidly sucked into a 10-mL glass syringe and then is injected into a test tube with conical bottom and the procedure is repeated seven times. After centrifuging the resulted cloudy solution, the derivatized analytes in the sedimented phase are determined by GC-FID. The influence of main factors on the efficiency of derivatization/extraction procedure is studied. Under the optimal conditions, the enrichment factors (EFs) for aliphatic amines are obtained in the range of 248–360 and limits of detection (LODs) are between 0.30 and 2.6 μg L⁻¹. The obtained extraction recoveries ranged from 50 to 72% and the relative standard deviation (RSD) was less than 4.8% for intra-day (n = 6) and inter-days (n = 4) precision. The method is successfully applied to determine some aliphatic amines in environmental water samples.     

Determination of aliphatic amines by gas chromatography–mass spectrometry after in-syringe derivatization with pentafluorobenzoyl chloride

A simple and highly sensitive gas chromatographic method has been developed for the determination of low molecular weight short-chain aliphatic amines (SCAAs) after their simultaneous extraction and in-syringe derivatization with pentafluorobenzoyl chloride (PFBOC). Derivatization of the low molecular weight aliphatic amines in bicarbonate buffer of pH 10.5 with PFBOC was followed by immersed solvent microextraction. Derivatization conditions, including reagent concentration, reaction pH, ionic concentration of buffer, reaction time, stirring rate, reaction temperature and extraction solvent, have been investigated for method optimization. Linearity was studied within range of 0.15 pg ml⁻¹–50 ng ml⁻¹. The correlation coefficients were between 0.9934 and 0.9999. Detection limit of derivatized amines proved to be in the range of 0.117–1.527 pg ml⁻¹, and the intraday and interday relative standard deviation (RSD) values were less than 8% with respect to peak area. The method was applied for analysis of lake, river and industrial waste water. The recoveries of extraction from lake, river and industrial waste water samples, which have been spiked with different levels of aliphatic amines, were in the range of 68–99%, 63–102% and 62–105%, respectively.     

Synthesis and properties of novel aliphatic polycarbonate from carbon dioxide with 1,2-butylene oxide and ε-caprolactone

A new degradable aliphatic poly(butylene-co-e-caprolactone carbonate) (PBCL) was synthesized through the terpolymerization of carbon dioxide, 1,2-butylene oxide (BO) and e-caprolactone (CL), a polymer supported bimetallic complex (PBM) was used as a catalyst. The terpolymers prepared were characterized by FT-IR,1H NMR, 13C NMR, WXRD and DSC. The hydrolysis tests were carried out to appraise the degradability of the copolymers.     

Synthesis of new β-hydroxy amide ligands and their Ti(IV) complex-catalyzed enantioselective alkynylation of aliphatic and vinyl aldehydes

Three new chiral β-hydroxy amide ligands were synthesized via the reaction of benzyl chloride and amino alcohols derived from l-tyrosine. The titanium(IV) complex of chiral ligand 8b was found to be an effective catalyst for the asymmetric alkynylation of aliphatic, vinyl and aromatic aldehydes. The propargyl alcohols were obtained in highly enantiomeric excesses (up to 96% ee) under optimized conditions.     

Segregated self-assembly and pillaring action of aliphatic dicarboxylic acids in the super structure of Cu–picolinate complexes

Three new supramolecular assemblies of co-crystallized metal complexes and aliphatic dicarboxylic acids, {[Cu(pic)₂(H₂O)₂](H₂mal)}_n (1), {[Cu(pic)₂(H₂O)₂](H₂mal)₂(H₂O)₂}_n (2) and {[Cu(pic)₂(MeOH)](H₂succ)}_n (3) {Hpic = 2-picolinic acid, H₂mal = malonic acid and H₂succ = succinic acid} have been synthesized and characterized by X-ray single-crystal structure determination. The crystal packings of the complexes reveal that supramolecular associations of the monomeric complex units lead to the formation of layers through hydrogen bonding. In all the complexes, the dicarboxylic acid units connect the 2-D layers to act as pillars. The interaction between water molecules and the dicarboxylic acid plays an important role in the overall supramolecular assembly.