首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到14条相似文献,搜索用时 78 毫秒
1.
采用半经验量子化学方法(MNDO,AM1和PM3)、从头算(采用STO-3G,3-21G,6-31G,6-31G^*,^6-31G^**,6-311G,6-311G^*和6-311G^**基组)HF方法计算羟基和6种脂肪醇盐离子以获得电子结构数据。通过相关分析发现脂肪醇盐离子中的氧原子净电荷,HOMO能级与质子亲和能之间具有良好的线性的相关性。  相似文献   

2.
曹晨忠 《有机化学》1995,15(6):642-646
脂肪族胺、醇和醚的气相质子亲合能(PA)与N, O原子所带电荷(qx)以及烷基的极化效应指数(PEI)的关系可表示为其中a、b、c为系数。回归分析结果表明, 上式较好地表达了脂肪族胺、醇和醚的气相碱性变化规律。  相似文献   

3.
脂肪胺的脂水分配系数与结构参数的关系   总被引:1,自引:1,他引:1  
李宝宗 《化学研究》2003,14(4):57-59
研究了脂肪胺的脂水分配系数实验值与半经验量子化学计算获得的理论计算参数值间的相关关系,结果表明:实验测定值与分子范德华体积及碳氮键长之间有良好的多元线性关系.  相似文献   

4.
有机物的气相碱性是指有机物分子在气相条件下与质子的亲合能力,通常用化合物的气相质子亲合能(PA)来表示,由于受到分子中不同取代基甚至不同空间构象的影响往往不同,因而很难测定。长期以来人们都是在溶液中测定有机物的碱性,高压质谱(HPMS)和离子回旋共振(ICR)等高新技术的发展和应用,使得人们在气相条件下测定分子本身固有的相对碱性成为可能。气相碱性比溶液中的碱性更能直接反映出化合物的分子结构特征,有利于有机化合物结构-性能/活性(QSPR/QSAR)关系的研究。  相似文献   

5.
脂肪族胺、醇和醚气相碱性的通用表达式   总被引:9,自引:0,他引:9  
曹晨忠 《有机化学》2000,20(2):258-262
脂肪族胺、醇和醚气相质子亲合能(PA)与N、O原子所带电荷(qx)、烷基的极化效应指数(PEI)以及N、O原子的sp^3杂化轨道能量[Ex(sp^3)]的并系可以表示为:PA(kj/mol)=2383.5547-1060.3351qx+59.4247∑PEI-117.0142Ex(sp^3)。上式较好地表达了脂肪族胺、醇和醚气相碱性的共同规律。  相似文献   

6.
莫凤奎 《有机化学》1983,3(2):120-122
本文给出计算脂肪族胺、醇和醚气相碱性的经验公式。由公式得出的PA值与ICR实验值接近。  相似文献   

7.
8.
诱导效应指数与脂肪族胺、醇和醚的气相碱性   总被引:4,自引:0,他引:4  
用烷基诱导效应指数I和RX分子中质子亲合原子X所带电荷qx及元素电负性XN与 脂肪胺,醇、醚的气相质子亲合PA进行关联,结果表明,脂肪胺,醇、醚的气相碱 性可以用下式定量描述:PA(kJ.mol^-1)-2732.0333-2457.1510∑I-1492.2351qx- 732.6277XN利用上式对64种化合物的气相碱性进行预测,平均相对误差为0.34% ,预测值和实验值的偏差均在实验误差范围内。  相似文献   

9.
Primary aliphatic amines were introduced into most of (>95%) carboxyl groups densely present on the TEMPO-oxidized cellulose nanofibril (TOCN) surfaces via carboxyl/amine salt formation in a water-isopropyl alcohol mixture. The carbon number of alkyl chain lengths introduced into TOCN varied using n-decyl-, n-dodecyl, n-tetradecyl-, n-hexadecyl- and n-octadecyl-amines. When n-dodecyl-, n-tetradecyl- and n-hexadecyl-amines were used for neutralization of carboxyl groups, the TOCN-COOH/amine salts were dispersed at the individual nanofibril level in pure isopropyl alcohol (IPA) by ultrasonication treatment, and gave stable and transparent IPA dispersions with birefringence when observed between cross polarizers. Flexible, highly transparent and surface-hydrophobic self-standing films of n-dodecylamine-treated TOCN-COOH (TOCN-COOH/C12-amine salt) were prepared by casting and drying of the dispersion. However, the introduction of abundant long-alkyl chains on the TOCN surfaces via the amine salt formation resulted in clearly lower mechanical and oxygen barrier properties of the films than those of TOCN-COONa films.  相似文献   

10.
Density functional methods have been employed to characterize the gas phase conformations of selenocysteine. The 33 stable conformers of selenocysteine have been located on the potential energy surface using density functional B3LYP/6‐31+G* method. The conformers are analyzed in terms of intramolecular hydrogen bonding interactions. The proton affinity, gas phase acidities, and bond dissociation energies have also been evaluated for different reactive sites of selenocysteine for the five lowest energy conformers at B3LYP/6‐311++G*//B3LYP/6‐31+G* level. Evaluation of these intrinsic properties reflects the antioxidant activity of selenium in selenocysteine. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008  相似文献   

11.
Structural Chemistry - Sulfinamides, as an asymmetric synthesizer, especially in drug synthesis, play critical roles in organic chemistry. In this study, the gas phase ion energetics data including...  相似文献   

12.
脂肪族胺、醇、醚气相碱性的模型研究   总被引:6,自引:0,他引:6  
以烷基极化效应指数(PEI)和分子中亲合原子的平衡电负性(XE)及亲合原子的Pauling电负性(X)为基本参数,研究了脂肪族胺、醇、醚的气相碱性(PA)的共同变化规律。结果表明,脂肪族胺、醇、醚的气相碱性可用下列通式来定量描述:PA(KJ/mol)=2468.6730+557.3172∑PEI-551.4261XE-1230.5770(∑PEI/XE)-111.5537X用上式预测了64种化合物的气相碱性,平均绝对相对误差仅为0.34%,预测值与文献值的偏差完全落在实验误差的范围内。  相似文献   

13.
The proton affinities of benzene, chlorobenzene and polychlorobenzenes with the common formula C6Cl n H6–n (n=0–6) have been calculated by the AM1 method. The proton affinity averaged over the protonated isomers increases monotonically asn growing from 0 to 5, and then decreases when passing from pentato hexachlorobenzene. The energies of proton addition to the different positions in the polychlorobenzene molecules have been estimated. It has been found that unsubstituted carbon atoms are preferred for proton attack. The positions with the highest proton affinity are the carbon atoms with the largest negative charges. The activation energies of 1,2-hydrogen shifts in arenonium ions of the polychlorobenzenes have been calculated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1213–1217, July, 1993.  相似文献   

14.
Isolated polyfluorobenzene (PFB) molecules and their protonated forms are investigated by the AM1 method with full geometry optimization. The proton affinities of PFB are estimated for different protonated positions. The proton affinity of PFB averaged over all isomers is shown to decrease monotonically as the number of fluorine atoms in the molecule increases. The relative populations of different isomers of arenonium ions (AI) formed by PFB protonation are determined. From the calculated data, the value of + for the F atom in theipso-position is estimated as 1.00. The activation energies of the 1,2-hydrogen shifts in AI are calculated. The dependences of the proton affinity and the activation energies of 1,2-hydrogen shifts on the number of halogen atoms are found to have distinct characters for PFB and polychlorobenzenes. The physical reasons for these difference are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1878–1882, November, 1993.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号