Study of the Lipophilicity and Retention Behavior of Some s-Triazine Derivatives on Aminoplast and Cellulose

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of four groups of s-triazine derivatives (15 compounds) has been studied on aminoplast and cellulose...     

土壤淋溶柱色谱中有机调节剂对保留的影响

 摘要：系统考察了55种非离子型化合物（包括11个氯代苯类、14个烷基苯类、22个多苯和多环芳烃类化合物、8个农药）在土壤淋溶柱色谱和较宽的淋洗剂（甲醇-水）组成范围内容量因子（k'）与甲醇体积分数（ψ）的关系。用自制加压装柱机将标准土壤干法装填成10mmi.d.×100mm的液相色谱柱,ψ=00.80的等度淋洗剂的流速1mL·min-1,柱温(25.0±0.1)℃,用UV检测器在线检测。实验表明,logk'=logkw+aψ+bψ2和logk'=logkw-Sψ两式均可以用来描述保留规律,但后者因其计算简     

反相毛细管电色谱中中性化合物的保留及有机改性剂对其保留值的影响

以硫脲作为电渗流标记物测定的死时间和以苯同系物线性回归方法测定的死时间为基础，将液相色谱中溶质保留值方程应用到电色谱中，得到了容量因子与二元流动相体系中有机改性剂含量之间的关系曲线；通过实验数据说明了一些极性的电中性化合物在电场作用下也会发生迁移而引起保留值的变化，且这种变化还受有机改性剂含量的影响。     

Partial Least-Squares Study of the Effects of Organic Modifier and Physicochemical Properties on the Retention of Some Thiazoles

JPC – Journal of Planar Chromatography – Modern TLC - Reversed-phase (RP) HPTLC with aqueous ammonia-organic modifier (acetonitrile, dioxane, acetone) mobile phases has been used to...     

The Synthesis of Some Amides of 1-Amino-l-deoxyglucitol and Correlation of Their Structures with the Tinti-Nofre Sweetness Model

Abstract

A series of amides of 1-amino-l-deoxy-D-glucitol and 1-deoxy-l-methylamino-D-glucitol was prepared as possible sweeteners. A crucial feature was direct amidation without blocking and deblocking. Several strategies to induce sweetness were considered and a study of the correlation of these compounds with the Tinti-Nofre model was conducted.     

Determination of the Lipophilicity of Some Psychotropic Drugs by RP-TLC

JPC – Journal of Planar Chromatography – Modern TLC - Psychotropic drugs have been chromatographed on RP-18-HPTLC plates with mobile phases containing water, an organic modifier...     

Correlation between the Structures of Some 2,4-Dioxotetrahydro-1,3-Thiazoles and TLC Retention Data

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic retention behavior of 3-ethyloxycarbonyl-5-substituted-2,4-dioxotetrahydro-1,3-thiazole derivatives has been...     

Evaluation of the Lipophilicity of Some 1-Arylpiperazines by Planar Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - The lipophilic character of some biologically active 1-arylpiperazines has been studied. A reversed-phase planar chromatographic...     

Lipophilicity of Some Preservatives Estimated by RP-TLC Using Stationary Phases with Different Polarity

Lipophilcity of some preservatives was determined by reversed phase high performance thin layer chromatography (RP-HPTLC) using methanol–water mixtures in different volume proportions as mobile phase on three stationary phases of different polarity: RP-18F_254s, RP-18WF_254s and CNF_254s plates. The R _M values decreased linearly with increasing methanol concentration in the mobile phase in all cases. The regression determination coefficients obtained for all stationary phases were excellent (higher than 0.98 in most cases). The chromatographic behavior of the preservatives on the RP-HPTLC plates used in this study is similar and in a very good agreement with their polarity. Good chromatographic regularities found for retention factors and by applying principal component analysis for all three types of stationary phases indicate that the same lipophilic interactions are dominants in all cases. The relationships between different RP-HPTLC retention parameters (R _M0 , b, scores of R _F -PC1/R _F and scores of R _M -PC1/R _M ) and various calculated log P values of the same preservatives show highly significant correlations for all types of stationary phases.     

Amides of the Hypophosphorous Acid: Some Properties and Application

Abstract

The interaction of 50% aqueous solution of hypophos-phorous acid (HPA) with some aromatic and aliphatic iso-cyanates (phenylisocyanate (PIC), 2,4-toluylenediisocyanate (TDI), butylisocyanate (BIC), and 1,6-hexamethylenediiso-cyanate (HMDI)) was investigated. PIC reacts only with water present in the system, yielding N,N-diphenylcarbamide. The interaction with TDI also leads to compounds possessing P-C bond. Their structure has been determined by IR- and NMR-spectroscopy. The interaction with aliphatic isocyana-tes proceeds mainly between the isocyanate groups and the acid P-OH group of HPA. Amides of HPA are obtained: N-butyk phosphamide and 1,6-N,N-hexamethylenediphosphamide. The structure of these compounds has been determined by IR-, ¹H-, and ³¹P-NMR-spectroscopy. 1,6-N,N-hexamethylenedi-phosphamide condenses with formaldehyde, yielding an olygo-meric product. The reaction proceeds mainly at the phosph-amide groups, but it has been established by ¹H- and ³¹P-NMR spectra, that the hydrogen atoms at the phosphorus also take part in the interaction. The prepared olygomer has also been characterized by gel-permeation-chromato-graphy. It possesses growth-regulating and cytokininic activity. 1,6-N,N-hexamethylenediphosphamide has also been tested as a fire retardant for rigid polyurethane foams.     

The Influence of Structure and Lipophilicity of Hydantoin Derivatives on Anticonvulsant Activity

The lipophilicity of a representative number of hydantoin derivatives was experimentally determined by RP-HPLC. The stationary phase of RP-HPLC proved a good model to simulate effects of membrane transport. These experimental values were correlated to theoretically estimated lipophilicity values on the basis of global minima structures of the compounds studied. Both these lipophilicity and structure similarities within a proposed pharmacological model for binding the hydantoin derivatives along the sodium channel were classified with respect to their biological activity.     

Effect of Temperature on the Variation of Retention Time of Unretained Compound and Retention Indices of Some Explosives and Related Compounds Calculated Using a Multiparametric Method in RP-LC

In reversed phase liquid chromatography (RP-LC), a multiparametric non-linear least-squares regression iterative method has been evaluated at different column temperatures (ranging from 30 to 60 °C in 5 °C steps) for calculating the retention time of the unretained compound t _M and the regression parameter (slope b), based on the use of alkan-2-ones, alkyl aryl ketones and 1-nitroalkanes homologous series on two different columns: Spherisorb-ODS2 C₁₈ and Nucleosil C₈. The calculated parameters t _M and b by the multiparametric method (MP) were compared with those obtained by using the iterative method of Guardino’s. The influence of the number of subsets of homologues used for the calculation of t _M and b values was investigated. The retention indices (RI) of some neutral and acidic explosives and related compounds (nitramines, nitroaromatics, aminonitroaromatics and nitrophenols) based on the alkan-2-ones retention index standards have been determined and compared at various temperatures by the MP method. Good agreement was observed between retention data calculated by the MP and GU methods.     

Reaction of Some Amides and Thioamides with Diazomethane Catalyzed by Silica Gel

Certain amides and thioamides can easily be methylated with diazomethane in the presence of silica gel.     

反相离子对色谱中有机溶剂浓度和溶质电荷数对保留值的影响

本文应用热力学的方法,导出了反相离子对色谱中有机溶剂浓度与保留值间的关系为: 1nk′_(ip)=1nk_(ip)~W+C_(ip)C_b 此关系式能很好地描述有机溶剂浓度对具有一、二和三价与离子对试剂反电荷溶质的保留值的影响。通过与溶质在反相色谱中保留行为的比较,确定静电力和分子作用力对参数1nk_(ip)~w和C_(ip)的贡献,而静电作用力与溶质的电荷数直接相关。通过对溶质电荷数对反相离子色谱中保留值贡献的修正,可估算溶质在反相色谱中的保留值。     

Retention of Th234 on Some Metal Sulphides

About 99% of active thorium and almost entire inactive thorium is retained on precipitates of tin disulphide and antimony sulphide. The absorption of inactive thorium is slightly faster than active thorium. The retention of active thorium decreases in presence of inactive thorium. Analysis of retention data confirms the heterogeneous distribution of thorium over the precipitate of Sn(IV) and Sb(III) sulphides. Retention takes place by absorption when precipitate is less. In presence of greater amount of precipitate inhomogeneous distribution and diffusion of thorium ions takes place.     

Cross‐Coupling of Secondary Amides with Tertiary Amides: The Use of Tertiary Amides as Surrogates of Alkyl Carbanions for Ketone Synthesis

In recent years, exciting progress has been made in the field of direct transformation of amides, nevertheless, the condensation between two amides remains rare and restricted to homo‐coupling reactions. Herein, we report the cross‐coupling of secondary amides with tertiary amides, which provides a synthesis of ketones under mild conditions, and features the use of tertiary amides as surrogates of alkyl carbanions. The method relies on the coupling of enamines, generated from tertiary amides by catalytic partial reduction of tertiary amides with Vaska's catalyst, with nitrilium ions, formed in situ from secondary amides via activation with trifluoromethanesulfonic anhydride, and on the subsequent deformylation.     

RP-TLC Determination of the Lipophilicity of Some New Derivatives of 1,2,4-Triazole and Thiosemicarbazide with Potential Antituberculosis Activity

JPC – Journal of Planar Chromatography – Modern TLC - The reversed-phase thin layer chromatographic retention behavior of some new derivatives of 1,2,4-triazole and thiosemicarbazide...     

Influence of Physicochemical Parameters of Some Ring-Substituted Phenol Derivatives on Their Retention on a Porous Graphitized Carbon Column

Abstract

The retention characteristics of 29 phenol derivatives were determined on a porous graphitized carbon column in unbuffered acetonitrile—water and methanol—water eluent mixtures at various organic phase concentrations. Each phenol derivative showed symmetric peaks in each eluent without buffers. Good linear correlations were found between the log k' value and the organic mobile phase concentration in the eluent. Principal component analysis indicated that methanol and acetonitrile expose different selectivities. Stepwise regression analysis proved that the retention of ring—substituted phenol derivatives is mainly governed by the sterical parameters, electron-withdrawing power and hydrogen donor capacity of substituents. According to the results of Free-Wilson analysis, the substituents with large steric parameters, strong electron-withdrawing power and hydrogen donor capacity have the highest impact on the retention. The lipophilicity of phenol derivatives did not affect significantly the retention, although the eluents were typical reversed-phase eluents.     

Effect of Type and Concentration of Organic Modifier in Aqueous Eluents on Retention in Reversed Phase Systems

Abstract

Retention - eluent composition relationships were determined for 18 compounds (phenols, quinoline bases, anilines) in chromatographic systems of water + organic modifier - oleyl alcohol (fixed on cellulose). Six organic modifiers were investigated: methanol, acetone, acetonitrile, 1,4-dioxane, dimethyl sulphoxide, acetic acid. Different eluotropic series were obtained depending upon the donor-acceptor properties of the solutes; for instance, dimethyl sulphoxide exhibited high eluent strength relative to phenols and anilines and acetic acid - to quinolines and anilines.