Solid Phase Derivatizations in HPLC: Polymeric Permanganate Oxidations of Alcohols and Aldehydes in HPLC-SPR

Abstract

On-line or off-line oxidations of various alcohols, aldehydes, and ketones can now be performed in conjunction with high performance liquid chromatography (HPLC), utilizing a newly developed polymeric permanganate solid phase reactor (SPR). These derivatization reactions are compatible with most reversed phase and normal phase solvents for HPLC separations, and many of these oxidations can be accomplished in real-time, on-line, at or above room temperature. Such HPLC-SPR approaches for chemical modifications and derivatizations of various oxidizable analytes provide a useful and quite practical newer approach for the HPLC-ultraviolet (UV) detection of appropriate analyte species. Difference chromatography, often with improved UV detection, can be used to confirm the suspected presence of a particular oxidizable analyte in a complex sample matrix. All of these solid phase derivatizations utilize conventional, commercially available HPLC instruments and accessories. These HPLC-SPR oxidation methods for chemical derivatization have also been applied to certain real world samples, in order to demonstrate the overall value and applicability of such analytical approaches.     

硼氢阴离子交换树脂的制备及其对羰基、酰氯化合物的还原

Gibson和Bailey首次应用Cl型季铵型强碱性阴离子交换树脂与NaBH_4交换,制备了硼氢阴离子交换树脂还原剂(简称BER)。     

New Fluorous Reversed Phase Silica Gels for HPLC Separations of Perfluorinated Compounds

Two new perfluoroalkyl-modified stationary phases were prepared and compared with two commercially available perfluorinated stationary phases (Fluophase RP and Fluophase Pentafluorophenyl) and a C₁₈-RP column with respect to retention times of an array of perfluoroalkyl-tagged and untagged molecules. A few highly lipophilic compounds were also included in the study. They showed high retention times on C₁₈-RP columns, but not on perfluorinated support materials. Perfluoroalkyl-tagged compounds revealed a weak interaction with the pentafluorophenyl-modified support. The interaction between perfluoroalkyl-tagged compounds and perfluoroalkyl-modified stationary phases was strong, and dependent on the chain length of the perfluoro tags. Surprisingly, there was only a small difference between the retention times of perfluorinated compounds on C₁₈-RP and C₆F₁₃-modified support. Fluorous-fluorous interactions became prevalent only with C₈F₁₇-tagged compounds on C₈F₁₇ functionalized silica gel. Compounds with two perfluoro tags showed a drastic increase in retention time, which might be due to a cooperative effect. These results demonstrate the uniqueness of fluorous-fluorous interactions based on linear perfluoroalkyl chains and open up possibilities for the design of new perfluoro tags for purifications and noncovalent attachments of catalysts or biomolecules on perfluorinated solid supports.     

Montmorillonite Supported Borohydride: A New Reducing Agent for Reductions Under Phase Transfer Conditions

A few cyclic and acyclic ketones were reduced in dichloro-methane, using reducing agents prepared from reusable montmorillonite clay supported phase transfer catalyst. A high percentage of axial attack (76–100%) by hydrides on substituted cyclohexanones observed, has been rationalised on the basis of a four center cyclic transition state for the clay absorbed ketone.     

姜黄素键合硅胶固定相HPLC分离碱性化合物

反相高效液相色谱法;姜黄素键合硅胶固定相;碱性化合物;色谱保留机理     

A New HPLC Method to Determine Carbonyl Compounds in Air

In this paper,a new HPLC method was established to determine the earbonyl compounds in air.As the absorbent,2,4-dinitrophenylhydrazint(2,4-DNPH)reaeted with earbonyls specifieally,which form the corresponding 2,4-dinitrophenylhydrazones,then analyzed by HPLC.The chromatographic conditions,the recovery rate,stability of samples,reagent blank,sampling efficiency were all studied systematically.The results showed that this established method had high sensitivity and good selectivity compared with other analytical methods,and it can detemine ten earbonyl compounds in air in 26 min simultancously.     

Silica Phenyl Sulfonic Acid as a Solid Acid Heterogeneous Catalyst for Chemoselective Thioacetalization of Carbonyl Compounds and Dethioacetalization under Mild Conditions

Silica phenyl sulfonic acid (SPSA) is an effective catalyst for chemoselective thioacetalization of aldehydes in the presence of ketones under neutral conditions. In addition, a simple and an efficient procedure for deprotection of 1,3‐dithianes and 1,3‐dithiolanes of aromatic, aliphatic, and α,β‐unsaturated aldehydes and ketones in the solvent‐free to the corresponding parent carbonyl compounds was successfully carried out with SPSA in excellent yields.     

简单芳香族醛、酮化合物相转移催化Kishner-Wolff反应

Kishner-wolff反应(简称K-W反应)是1911-1912年发现的,它是还原醛和酮的腙或缩氨脲为烃的著名方法。黄鸣龙、Cram、Grundon等人曾研究过此反应。1979年,我们用冠醚作相转移催化剂实现了相转移催化K-W反应。本文探讨了相转移催化K-W反应的适用范围。研究了八个芳香族醛、酮化合物的还原,其结果列于表1。     

硅胶硫酸催化肟转化为羰基化合物的有效方法

在硅胶硫酸催化和十二烷基磺酸钠存在下,肟与多聚甲醛在90℃的水溶液中搅拌反应15～120 min生成相应的羰基化合物,收率68%～98%.     

广州市住宅室内外大气羰基化合物的监测分析

选择代表性住宅,在其室内、外同步开展大气羰基化合物的监测分析,准确评价大气羰基化合物的污染状况,揭示其来源。用涂覆2,4-硝基苯肼(DNPH)的硅胶采样管收集羰基化合物,借助高效液相色谱完成样品分析,共检测了13种羰基化合物,其中甲醛、乙醛两种物质的平均浓度最高,占被测物质总浓度的30%~67%。甲醛、乙醛的浓度,夏季室内平均为53.47μg/m3、17.81μg/m3,室外平均为15.00μg/m3、10.97μg/m3;冬季室内平均为37.97μg/m3、11.49μg/m3,室外平均为10.44μg/m3、8.15μg/m3。大气羰基化合物呈现夏季高于冬季、室内大于室外的浓度变化规律。甲醛/乙醛和乙醛/丙醛比值结果反映城市大气羰基化合物的人为污染。     

固相萃取/高效液相色谱法对肝癌细胞中多西紫杉醇的测定

建立了固相萃取/高效液相色谱法测定肝癌细胞中多西紫杉醇浓度的方法。细胞样品经三氯乙酸沉淀蛋白,Bond-elut C18固相萃取柱提取,采用Agilent TC-C18(5μm,4.6 mm×150 mm)色谱柱分析,以乙腈-0.02 mol/L醋酸铵缓冲液(体积比50∶50,醋酸调至pH5.0)为流动相,流速为1 mL/min,检测波长为230nm,进样体积为20μL。多西紫杉醇的质量浓度在0.05~2.25 mg/L范围内线性关系良好,相关系数r=0.999 3,检出限为0.03 mg/L,提取回收率为93%~95%,其日内、日间精密度(n=5)不大于6.9%,且稳定性良好。方法简便、快速、灵敏度高、干扰小,可用于生物样品中低浓度多西紫杉醇的测定。     

Chemoselective Protection of Carbonyl Compounds as Dithioacetals Using Silica Gel Supported Aluminium Chloride

Abstract

Silica gel supported aluminium chloride is shown to be a mild chemoselective catalyst for dithioacetalization of carbonyl compounds.     

Ceric Ammonium Nitrate on Silica Gel for Solid–Solid Phase N-Dearylation of β -Lactams

Silica gel–supported ceric ammonium nitrate (CAN-SiO ₂ ) has been found to be an effective reagent for the solid–solid phase and solvent-free N-dearylation of β-lactams. The results have been compared with CAN alone in solution and solid–solid phase.     

Borohydride Reductions in Dichloromethane: A Convenient,Environmentally Compatible Procedure for the Methylation of Amines

The combination of zinc chloride and sodium borohydride in dichloromethane is used to effect reductive aminations of formaldehyde with a variety of primary and secondary amines containing potentially acid-sensitive functional groups in good to excellent yields.     

Microwave-Assisted Chemoselective Regeneration of Carbonyl Compounds from Oximes by Silica Chromate/WET SiO2 Under Solvent-Free Conditions

The regeneration of carbonyl compounds from oximes were performed by using silica chromate and wet SiO ₂ (w/w 50%) under microwave irradiation and solvent-free conditions with excellent yields.     

The Forgotten Carbonyl Reaction: Chloroacetylation and Bromoacetylation of Carbonyl Compounds

Halomethyl acetates ( 3 ) could be prepared from aliphatic, α,β‐unsaturated and aromatic aldehydes, as well as from alicyclic ketones with high yields in simple one‐pot reactions. Very often, the products didn't have to be purified and could directly be used for synthetic purposes after evaporation of the solvent. Obviously, the ‘bad reputation’ of the reaction in the literature stemed from the fact that the reactions didn't take place under the best conditions. Carbonyl compounds ( 1 ) and acyl halides ( 2 ) form equilibria which are completely on the side of the halomethyl acetates ( 3 ) at room temperature (starting with aliphatic and most aromatic aldehydes) and which can be strongly influenced by the reaction parameters. It is crucial to work at low temperature in apolar solvents and to remove (or deactivate) the catalyst before workup. Reactions may be realized with or without solvents. Side reactions were observed with formaldehyde and acetaldehyde but, with exception of formaldehyde, could be reduced close to zero (see Fig. 5). By‐products were essentially avoided if the reaction took place in apolar solvents and with a local excess of acetyl chloride. In many cases clean products were available which could directly be used for synthetic purposes. Halomethyl acetates ( 3 ) are bifunctional carbonyl derivatives with two different leaving groups, whose preparative advantages have been useful for the synthesis of various pentafulvenes, but were especially important for preparing unstable parent fulvenes and fulvalenes.     

Silica Gel Supported Chromium Trioxide: An Efficient Reagent for Oxidative Cleavage of Oximes to Carbonyl Compounds under Mild Condition

A facile, efficient oxidative deblocking of aldoximes and ketoximes to their corresponding aldehydes and ketones have been achieved by using silica gel supported chromium trioxide.     

Preparation and Evaluation of 3,5-Dinitrobenzoyl-Bonded Silica Gel Stationary Phase for HPLC

Column packing materials are always a key factor influencing the development of high-performance liquid chromatography (HPLC). In this paper, a new preparation method of 3,5-dinitrobenzoyl-bonded silica gel stationary phase (DNB) for HPLC was developed by using N-(β-aminoethyl)-γ-aminopropyl-methyldimethoxy silane as coupling reagent. Its structure was characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy, and thermal analysis. The surface concentration of 3,5-dinitrobenzoyl ligand is 2.082 μmol m⁻², according to the carbon content of elemental analysis. The chromatographic performance of new packing was evaluated by using different solute probes, such as alkylbenzenes, polycyclic hydrocarbons (PAHs), phenols, naphthalene derivatives, nitrophenol positional isomers, and sulfonamides. The results show that DNB was of the reversed-phase packing kind with weak hydrophobicity and versatile chromatographic property compared with octadecyl silane. The charge transfer between the dinitrobenzoyl ligand and the analytes plays a significant role in the separation of phenols and naphthalene derivatives. In addition, electrostatic, hydrogen-bonding, and dipole-dipole interactions are responsible for the above separations, which improve the selectivity of DNB for solutes. An advantage of DNB is that it is suitable for the separation of the basic compounds containing nitrogen atoms without a capped process because the spacer containing nitrogen atoms can shield the residual silanols from DNB. Translated from Chinese Journal of Chromatography, 2005, 23(3) (in Chinese)     

Selective Reductions with Sodium Borohydride in Dimethyl Sulphoxide with Added Metal Salts

Sodium borohydride in Dimethyl Sulphoxide in the presence of added metal salts selectively reduces aldehydes in the presence of ketones and converts α,β -unsaturated ketones to the corresponding unsaturated alcohols.