Excess Molar Volumes of Binary Mixtures of Propyl Ethanoate with some n-Alkanes at 298.15 K and 308.15 K

Abstract

Excess molar volumes v^E have been measured for the binary liquid mixtures of propyl ethanoate with five n-alkanes (n-hexane, n-heptane, n-octane, n-nonane and n-decane) at 298.15 and 308.15 K, using an Anton Paar densimeter. All the mixtures studied present positive v^E values that increase with the length of the chain of the alkane and with the temperature. The experimental results are compared with the predictions of the Nitta—Chao model.     

Synthesis and reactivity of bis(cycloamidinium-2-yl)alkane bromide tribromides,brominating agents and tectons for molecular engineering

Bis(cycloamidine-2-yl)alkanes easily form bromide tribromide salts in the reduction-oxidation processes with bromine. Bis(tetrahydroimidazolium-2-yl)ethane and bis(hexahydropyrimidinium-2-yl)-ethane bromide tribromides are such new convenient brominating agents for aromatic amides in chemo- and regioselective electrophilic substitutions and α-bromination reactions. Correspondence: Katarzyna Ostrowska, Department of Organic Chemistry, Jagiellonian University, R. Ingardena 3, PL-30060 Kraków, Poland.     

改性纳米HZSM-5沸石催化剂上C5～C8混合烷烃的芳构化反应

在小型固定床反应器上研究了水蒸气钝化及过渡金属(Ni,Co,Cu,Zn)改性对调变纳米HZSM-5沸石催化剂上C5~C8混合烷烃芳构化反应的作用.采用NH3-TPD和Py-FT-IR方法表征了改性催化剂的表面酸性质,并与其催化芳构化性能进行了关联.结果表明,在450℃下进行水蒸气钝化能显著提高催化剂的芳构化选择性,减少甲烷和乙烷等低碳烷烃的生成;催化剂进一步用锌盐或铜盐溶液浸渍改性,可以显著提高催化剂的抗积炭失活能力.这是由于水蒸气钝化能适当减少沸石表面的酸量,降低酸强度,而铜、锌改性可进一步减少B酸中心,增加L酸中心,并与B酸中心协同作用形成具有脱氢活性的催化中心,从而影响混合烷烃的活化方式与芳构化路径.     

Diamonds are a chemist's best friend: diamondoid chemistry beyond adamantane

Marilyn Monroe knew that "diamonds are a girl's best friend" but, in the meantime, many chemists have realized that they are also extremely attractive objects in contemporary chemistry. The chemist's diamonds are usually quite small (herein: nanometer-sized "diamondoids") and as a result of their unique structure are unusual chemical building blocks. Since lower diamondoids (up to triamantane) have recently become available in large amounts from petroleum and higher diamondoids (starting from tetramantane) are now also accessible from crude oil new research involving them has begun to emerge. Having well-defined structures makes these cage compounds so special compared to other nanometer-scale diamonds. Selective and high-yielding synthetic approaches to the functionalization of diamondoids gives derivatives that can find applications in, for example, polymers, coating materials, drugs, and molecular electronics.     

Cu（BF4）2，Cu（C3H7C00）2与双（二苯膦基）烷烃配体形成配位化合物的红外光谱

用红外光谱法对二苯基膦系列配体及其分别与Cu(BF4)2和Cu(C3H7C00)2形成的系列配位化合物进行了研究，讨论了谱带的归属和Cu(I)配合物形成前后相关谱带的变化规律，并参照元素分析、X—射线粉末衍射分析和热重分析的结果，讨论了所形成配位化合物的可能的结构模式。     

2-Cyclopropyliden-1,3-cycloalkandione als Zwischenstufen einer nukleophilen Substitution am Dreiring

Reaction of morpholinobicycloalkyl-dimedone4 C with various CH-acids3 leads to a substitution of theexo-dimedone unit as a consequence of a strong preference of theexo-leaving group in a bicyclic compound of type4 and5, respectively. Dimedone (3 C) as a nucleophile, however, makes theexo substitution unproductive in4 C and allows the displacement of the morpholino moiety leading to12 C. Thus compounds12 C–12 F could be obtained directly from the N,O-acetal1 and the CH-acids3 C–3 F by a twofold substitution, the isolation of the monoalkylated compounds4 not being necessary. Formation of12 C–12 F involves aMichael addition of3 C–3 F to the unstable 2-Cyclopropylidene-1,3-cycloalkanedione intermediates7 C–7 F. Cyclopentanedione3 F as a CH-acid and1 gave the enamine17 F besides12 F. The Hexahydroazepino-N,O-acetal19 in this special case was superior leading exclusively to12 F.

     

Additive Schemes for Calculating the Properties of Alkane Conformers Including Interdependent Bond Rotation. I. Enthalpy

A technique is suggested for evaluating the properties of alkane conformers using the parameters of internal rotation of interdependent C-C bonds. To determine the mean conformational composition of a rotational equilibrium mixture of alkane conformers, one need not exhaust the latter because the contribution of the conformation energy to alkane enthalpy can be expressed in terms of the product of tensors with further convolution over indices.     

Microcalorimetric determination of enthalpies of solution of methyl alkanes in glacial acetic acid

An empirical equation H _{s, m}=0.84n gives the enthalpy of solution of 30 branched, linear and cyclic alkanes in glacial acetic acid. The parametern is an effective carbon number which expresses the number of carbon atoms in the longest chain plus one half of the pendant methyl groups.