Synthesis,characterization, and degradation of poly(anhydride‐co‐amide)s and their blends with polylactide

In attempt to improve the properties of polyanhydrides based on aliphatic anhydrides, we synthesized novel polyanhydrides containing amide groups in the main chains. In this work, N,N′‐bis(L ‐alanine)‐sebacoylamide (BSAM) was prepared from natural amino acid and sebacic acid (SA) and characterized by IR and ¹H NMR. In addition, polymers of PBSAM, P[1,6‐bis(P‐carboxyphenoxy) hexane (CPH)‐BSAM], and P(CPH‐SA), blends of P(CPH‐SA)/polylactide (PLA), P(CPH‐BSAM)/PLA were also prepared and characterized by IR, gel permeation chromatography, and differential scanning calorimetry. The hydrolytic degradation of polyanhydrides and their blends with PLA (number‐average molecular weight = 2.90 × 10⁵) was evaluated in 0.1 M phosphate buffer pH 7.4 at 37 °C. The results indicate that the existence of amide, aromatic, and ester bonds in the main chain of polymers slows down the degradation rate, and the tendency becomes clearer with the increasing amount of them, and the copolymers and their blends with PLA possess excellent physical and mechanical properties. These can make them more widely used in drug delivery and nerve regeneration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4311–4317, 2004     

Synthesis,crystal structure,and characterizations of a 3-D Cu(I) complex with 1,6-bi(benzotriazole)hexane

Solvothermal reaction of the flexible ligand 1,6-bi(benzotriazole)hexane (BBTH) with CuCl generated a 3-D hybrid solid, {[CuCl]₂(BBTH)} _n (1), which was investigated by elemental analysis, FT-IR, X-ray powder diffraction (XRPD), X-ray single-crystal diffraction, TG/DTA, and photoluminescence measurements. Compound 1 crystallizes in the tetragonal system, space group I4(1)/a, a = b = 17.636(2) Å, c = 13.5345(15) Å, V = 4209.6(9) ų, Z = 8. The distorted tetrahedral geometry of Cu(I) is defined by two chlorides and two N donors from different BBTH ligands. Adjacent copper atoms are connected by μ₂-Cl to give a 1-D zigzag inorganic chain, and further linked by BBTH ligands via μ₄-bridging, forming the 3-D hybrid structure of 1. Cu(I) atoms and BBTH ligands can be regarded as two kinds of non-equivalent 4-connected nodes, which lead to an unusual topological network with Schläfli symbol of (3².8.9².10)₂(3².8².9²). Compound 1 exhibits high thermal stability and shows strong red fluorescence emission at 538 nm in the solid state at ambient temperature.     

Model for alkanol + alkane mixtures: Extension and experimental verification

A recently developed model for 1-alkanol+alkane mixtures is extended to methanol mixtures and to the non-polar mixing partners tetrachloromethane and benzene. The model contains chemical and physical terms, which are combined in a thermodynamically consistent way. For our calculations on methanol mixtures, we have measured g ^E of methanol+ hexane via static vapor pressure measurements. In order to check the model predictions for systems with higher alkanols and alkanes, we have also determined g ^E of 1-octanol+tetradecane by measuring the melting curve. The reproduction of the excess properties of methanol+hexane, the agreement between predicted and measured values of g ^E for 1-octanol+ tetradecane, and the capability to deal also with other non-polar mixing partners demonstrate the power and reliability of the model.Communicated at the Festsymposium celebrating Dr. Henry V. Kehiaian's 60^th birthday, Clermont-Ferrand, France, 17–18 May 1990.     

Isobaric thermal expansion and isothermal compressibility of ethylbenzene + n-hexane,and + n-octane at 25 and 45°C

Isobaric thermal expansion _p, and isothermal compressibility _p have been determined for binary mixtures of ethylbenzene + n-hexane, and + n-octane in the complete range of composition at 25 and 45°C. The corresponding excess quantities obtained at each measured mole fraction are negative for both systems and show minima at or around equimolecular composition. Absolute values of those excess functions decrease with the chain length of the n-alkane and increase with temperature. Combining these experimental results with data for the heat capacity at constant pressure the isentropic compressibility and the heat capacity at constant volume were calculated at 25°C. The corresponding excess quantities are negative, showing maxima around mole fraction 0.5 and their absolute values decrease for _S ^E and increase for C _V with increasing chain length.     

Bioreduction of quinone derivatives by immobilized Baker''''s yeast in hexane

Immobilization techniques and biocatalytic transformations performed in organic media are new developing methods for organic reactions. Baker's yeast was immobilized on the alginate supports. This preparation contained about 20% of dry yeast cells. The immobilized Baker's yeast were found to be very effective in the reduction of o-benzoquinone, p-benzoquinones, naphthoquinones, and anthraquinones in hexane.     

沸石负载的钒络合物催化剂对烷烃氧化反应的催化性能

 将钒氧吡啶甲基络合物VO（pic）2负载于Y及ZSM－5沸石分子筛\r\n中，制备出沸石负载的钒络合物催化剂．用X射线衍射、电子自旋共振\r\n、红外光谱和元素分析等方法对催化剂进行了表征．结果表明，VO（p\r\nic）2络合物确实负载于分子筛孔道内，负载后的络合物仍保持着原来\r\n的结构．考察了催化剂对正己烷和环己烷氧化反应的催化性能，发现沸\r\n石分子筛负载的VO（pic）2络合物催化剂保留有络合物原有的催化性能\r\n，虽然催化活性有所下降，但显示出较好的形状选择性．与未负载的络\r\n合物相比，NaY和ZSM－5沸石负载的VO（pic）2络合物催化剂对正己烷\r\n氧化反应的伯醇选择性分别提高了2～3倍和5～6倍．     

直链烷烃对Ti-HMS分子筛合成的影响

以十二胺为模板剂,正硅酸乙酯为硅源,钛酸四丁酯为钛源,直链烷烃正己烷或正辛烷为有机添加剂,在室温下合成出具有较大孔径的Ti-HMS分子筛.研究了烷烃对Ti-HMS分子筛的扩孔作用及对分子筛结晶度和催化性能的影响.结果表明,加入的烷烃越多,分子筛的孔径越大;烷烃链长越长,对Ti-HMS的扩孔作用越显著.与不加烷烃的Ti-HMS相比,加入烷烃后,分子筛的结晶度及四配位骨架钛的含量均有所降低,而且加入的烷烃量越多,影响越明显.将加入烷烃所得的Ti-HMS用于模拟燃料中4,6-二甲基二苯并噻吩的氧化脱除反应,结果发现,Ti-HMS的催化氧化活性有所提高,对4,6-二甲基二苯并噻吩的脱除速率增大.     

The enthalpies of mixing of organophosphate esters with hydrocarbons

Heats of mixing were obtained calorimetrically at 298°K for each of the phosphate esters tri-n-butylphosphate (TBP), bis(2-ethylhexyl)phosphate [(H)DE-HP], and di-n-butylphosphate [(H)DBP] withn-dodecane and with 1,3-diethylbenzene. These data and data from the literature on Gibbs free energies and heats of mixing of the phosphate esters with decane, hexane, and benzene are interpreted according to a nonideal associated mixture model. This takes into account the size effect, nonspecific (regular-type) interactions, and association to dimers, which is partial for TBP and complete for the acidic esters, which in turn associate further to trimers and possibly higher oligomers. The enthalpies of mixing with the aliphatic hydrocarbons involve two parameters, one describing the association and the other the nonspecific interaction, and independently obtained quantities. The enthalpies of mixing with the aromatic hydrocarbons require further parameters, involving the mutual interactions, which could not be calculated.     

Solubility of inert gases and liquid hydrocarbons in water

The thermodynamic statistical model based on the distribution of molecular populations among energy levels has been employed for the analysis of the solubility of hydrocarbons and other inert gases or liquids in water at different temperatures. The statistical distribution is described by a convoluted partition function Z_G·_s. The product of a grand canonical partition function Z_G represents the distribution of the species in the reaction while the canonical partition function Z_G represents the properties of the solvent. The first derivative of the logarithm of the partition function with respect to 1/T is the apparent enthalpy which is the result of the contributions of the separate partition functions, {H_aap}_T=H^o+n_wC_p,wT, where {H_app}_T refers to Z_G, n_wC_p,wT=–H_w to _s, and H^o is the change in enthalpy of hydrocarbon-water reaction. The plot {H_app}_T vs/ T results in a straight line with slope n_w at constant C_p,w. The apparent enthalpy is obtained from the coefficients of the polynomial fitting of the solubility data, as a function of 1/T. Alternatively, the apparent enthalpy can be determined calorimetrically. The enthalpy thus obtained is a linear function of the Kelvin temperature. The values of n_w range from 1.6, 1.9, 5.6 to 5.8 for helium, hydorgen, butane and hexane, respectively. For fluorocompounds the range of n_w is 10.1 to 11.1 indicating that n_w is a function of the number of water molecules expelled from the cage of solvent to form a cavity to host the solute molecule. The analysis of several sets of calorimetric or solubility data with the present molecular thermodynamic model yields values of H^o and n_w consistent with the size of the dissolved molecules.List of Symbols p pressure - H _ij average enthalpy - H _i level enthalpy (=H) - H _i enthalpy difference - H _ij intersublevel energy difference - i index of level - j index of sublevel - Z_G grand canonical partition function - _S canonical partition function - Z_G- convoluted partition function - –G ^o/RT standard Gibbs energy normalized toRT - –H ^o/RT standard enthalpy normalized toRT - S ^o/R standard entropy normalized toR - C _p molar heat capacity - T absolute temperature - H _G- enthalpy of the convoluted ensemble - H _G enthalpy of the solute - H enthalpy of the solvent - H _app apparent enthalpy - H _w enthalpy of water - C_yH_z hydrocarbon - W water - K _s solubility equilibrium constant - x ₂ molar fraction of solute - C_yH_zW_(x-nw) hydrocarbon molecule trapped in a cavity - K _H Henry constant - P _s solubility product - [W] concentration of water - reference temperature - a, b, c, d coefficients of the fitting polynomial - {H _app}_T apparent enthalpy at temperatureT - {H }_T standard enthalpy at temperatureT - {H _w}_T water contribution to enthalpy at temperatureT - C _p,w isobaric molar heat capacity of water - L Ostwald coefficient - C _p isobaric heat capacity difference - Bunsen coefficient - C _p,app apparent isobaric heat capacity difference - n _C number of carbon atoms in the chain - h _w interaction enthalpy of one water molecule - H ₀ intercept for the extrapolated enthalpy     

Volumes of mixing and theP * effect: Part II. Mixtures of alkanes with liquids of different internal pressures

The Flory theory of solution thermodynamics is used to predict exess volumes for systems containing a series of n-alkanes mixed with liquids of higher P^* parameter and internal pressure, i.e., cyclopentane, cyclohexane, carbon tetrachloride, benzene and dioxane as well as of lower P^*, i.e., decamethyltetrasiloxane. Trends of V ^E , e.g. changes of sign with alkane carbon number are well predicted and indicate the importance of the P^* contribution in V ^E . Mixtures of hexane isomers with liquids of much higher P^* typically have large excess enthalpies through zero as an S-shaped curve against composition which is negative on the side of the high P^* component. This behaviour is interpreted as arising from increasingly large negative P^* contributions in V ^E .