高效液相色谱法同时测定染发剂中11种氨基苯酚

建立了高效液相色谱测定直接型与氧化型染发剂中11种氨基苯酚含量的分析方法。样品在亚硫酸氢钠的保护下用甲醇提取,高速冷冻离心净化;采用Agilent Zorbax SB C18色谱柱分离,流动相为5 mmol/L庚烷磺酸钠-40 mmol/L pH 2.8磷酸盐缓冲液和乙腈,梯度洗脱,11种氨基苯酚分别于230、270和400 nm下检测。11种氨基苯酚在0.05～500 mg/L线性范围内相关系数不小于0.9992,4-氨基-3-硝基苯酚、2-氨基-5-硝基苯酚、3-硝基-4-(2-羟乙基)氨基苯酚的方法定量限为5 mg/kg,其他8种氨基苯酚包括对氨基苯酚、对甲氨基苯酚、间氨基苯酚、邻氨基苯酚、5-氨基-2-甲基苯酚、4-氨基-3-甲基苯酚、2-甲基-5-(2-羟乙基)氨基苯酚和2-氨基-4-硝基苯酚定量限为20 mg/kg,方法回收率为88.5%～109.5%,相对标准偏差为2.2%～8.3%。测定了多种市售染发剂,结果表明该方法操作简单、测定结果准确,可用于直接型与氧化型染发剂中11种氨基苯酚的测定。     

Determination of dye precursors in hair coloring products by liquid chromatography with electrochemical detection

The simultaneous determination of seven aminophenols, resorcinol and p-phenylenediamine in hair coloring products was performed by liquid chromatography (HPLC) with amperometric detection (ED). The aminophenols were separated on a ODS C18 reversed-phase column by isocratic elution with a mobile phase based on 0.1 M acetate buffer pH 4.5-methanol (90:10%, v/v) at a flow rate 0.8 mL min⁻¹. The limit of detection (S/N = 3) for the aminophenols was in the 15-40 pg (injected mass) range at an applied potential of 0.950 V versus Ag/AgCl. Peak heights for the aminophenols and the two others compounds were found to be linearly related to the amount injected, from 0.3 to 300 ng (r > 0.994-0.999).The relative standard deviation (R.S.D., n = 10) for 1 ng injected was comprised in the range from 2.5 to 6.2%, depending on the aminophenol tested. The present method minimizes troublesome and time-consuming pretreatment procedures and it was applied to the determination of aminophenols, resorcinol and phenylenediamine in hair coloring formulations.     

Self-regulating polycondensations: Ordered aromatic polyamide-esters

The polycondensation of aminophenols with diacid chlorides was examined to determine if the amide-ester polymers obtained are random or ordered. All of the evidence obtained points to the conclusion that ordered copolymers indeed are prepared and that a “self-regulating” polymerization process is operating by virtue of the considerably greater reactivity of aromatic amino groups relative to phenol groups. The first step of the reaction involves the in situ preparation of a diphenol-amide which undergoes further condensation. The diphenol-amide intermediate may be isolated or reacted in situ. In addition to the ordered polymer from a given aminophenol and a single diacid chloride, ordered copolymers from two different diacid chlorides were prepared in which the diacid moieties appear in an alternating fashion; the structure of such polymers depends on the order of addition of the diacid chlorides. Corresponding polymers also may be prepared from the preformed diphenol-amide monomers. The molecular weights of certain of the polymers were sufficient for the preparation of films which could be hot-stretched severalfold. Interfacial polycondensations gave polymers of higher inherent viscosities than did solution polymerizations when aminophenols or diphenol-amide monomers were condensed with diacid chlorides.     

A New Anionic Micellar Mobile Phase System for the Normal-Phase Thin-Layer Chromatography of Amino Compounds: Simultaneous Separation of Aminophenol Isomers

The chromatography of some amino compounds was performed on high-performance thin-layer plates (silica-gel 60 F₂₅₄, catalog no. 1.05554, Merck, Germany) using aqueous and alcoholic (MeOH) and aqueous–organic solutions of cationic, anionic, and nonionic surfactants. The results obtained with 0.01 M aqueous sodium dodecyl sulfate (SDS) have been compared with distilled water (i.e., zero SDS) as the eluent. The effects of the surfactant concentration, the nature of the alcohol, and the presence of inorganic salts (NaCl, LiCl, CaCl₂, and CoCl₂) in the mobile phase were examined in order to understand the mobility pattern of amino compounds. Among the added salts, CaCl₂ was found to be the most effective for facilitating an analytically important separation of coexisting ortho-, meta-, and para-aminophenols. The TLC system consisting of a precoated high-performance silica layer as the stationary phase and 0.01 M methanolic SDS plus 0.1 M CaCl₂ in a 3 : 7 ratio as the mobile phase was identified as the most suitable system for the separation of o-, m-, and p-APHS from their mixtures. The influence of various impurities, such as amines, phenols, and inorganic cations, on the mobility and the separation of coexisting aminophenol isomers has also been examined. The lower limits of detection of aminophenols were determined on HPTLC plates using I₂ vapors as the detection reagent.     

Characterization of aminophenol isomer adsorption on silver nanostructures

Surface-enhanced infrared absorption (SEIRA), temperature-programmed desorption, and density functional theory calculations were used to explore the adsorption of aminophenol isomers on vacuum deposited silver films and silver powder. Salts of the aminophenolate ions were synthesized to aid in vibrational spectral interpretation. No evidence for dissociation of any of the aminophenols into aminophenolate ions in the monolayer or multilayer was found when adsorbed on silver nanostructures (SNS). SEIRA demonstrated additional hydrogen-bonding interactions in a multilayer of 2-aminophenol and 3-aminophenol adsorbed on SNS beyond what is present in the aminophenol powders. Surface-enhanced Raman spectroscopy (SERS) experiments also showed that a 2-aminophenol monolayer adsorbed on SNS is photolytically oxidized to either 3-aminophenoxazone or 2,2′-dihydroxyazobenzene, while neither 3-aminophenol nor 4-aminophenol showed any SERS activity. This work is expected to have a significant impact in a range of environmental, biochemical, and industrial applications where phenol chemistry is important.     

超高效液相色谱-串联质谱法测定染发剂中7种酚类化合物

提出了应用超高效液相色谱-串联质谱法同时测定染发剂中4-氨基-2-硝基苯酚、3-二乙氨基酚、2-氨基-4-氯苯酚、2-氨基-5-硝基苯酚、2-氨基-3-硝基苯酚、1,7-二羟基萘酚和2,3-二羟基萘酚等7种酚类化合物的方法。采用甲醇萃取染发剂中酚类成分,经WatersAcquityUPLCTMBEHC18色谱柱分离,外标法定量,多反应监测模式采集质谱数据。7种酚类化合物的检出限(3S/N)均低于50.0μg.L-1。在10,20,50μg.g-1三个添加水平下,7种酚类化合物的回收率在68.8%～112.5%之间,相对标准偏差(n=6)在1.58%～12.61%之间。     

Chloroform-soluble schiff-base Zn(II) or Cd(II) complexes from a dynamic combinatorial library

A dynamic combinatorial library of metal ion Schiff-base complexes have been studied for the extraction of Zn(II) or Cd(II) from aqueous solution into chloroform. Library components consist of different aminophenols and 2-pyridinecarboxaldehyde. Extraction of both Zn(II) and Cd(II) into chloroform was observed from aqueous solutions containing 0.0500 mM M(NO3)2, 0.100 M aminophenol, 0.100 M 2-pyridinecarboxaldehyde, 0.100 M NaCl, and 5.00 mM buffer at pH 8.5. Extraction was dependent on pH but not on counterions including Cl-, Br-, or NO3-. Studies showed that equilibrium was attained between the Schiff-base complexes across the two-phase chloroform-water system after 24 h of stirring. Analysis of the extracted species by use of 1H NMR spectroscopy and mass spectrometry as well as solubility studies on characterized complexes suggested that the major extracted species is the neutral bis-Schiff-base metal ion complex. In libraries containing mixtures of two different aminophenols and 2-pyridinecarboxaldehyde, an enhanced extent of extraction of Zn(II) into chloroform is observed. Studies suggest that a Zn(II) complex, which is likely the mixed Schiff-base complex, has superior extraction properties compared to simple libraries with a single aminophenol component. The structures of two bis-Schiff-base complexes of Zn(II) and one of Cd(II) have been determined by X-ray crystallography. The geometries of the two Zn(II) complexes, which differ only by a methyl substituent on the Schiff-base ligand, are markedly different, supporting the use of combinatorial methods in coordination chemistry. Zn(SB14)2 crystallized as the sesquihydrate (C24H18N4O2Zn.1.5 H2O) in the space group C2/c, with cell dimensions a = 23.219(15) A, b = 11.299(7) A, c = 16.822(11) A, beta = 102.91(5) degrees, V = 4302(5) A3, and Z = 8. Zn(SB15)2 crystallized as a 1:1 methanol solvate (C26H22N4O2Zn.CH3OH) in the space group P2(1)/c with cell dimensions a = 13.981(5) A, b = 7.978(3) A, c = 22.568(8) A, beta = 104.53(3) degrees, V = 2436.8(15) A3, and Z = 4. Cd(SB14)2 crystallized as a 1:1 ethanol solvate (C24H18N4O2Cd.CH3CH2OH) in the space group R3 with unit cell dimensions of a = 36.423(2) A, c = 9.2930(10) A, V = 10678(2) A3, and Z = 18.     

Cyclodextrin-based artificial oxidases with high rate accelerations and selectivity

Three cyclodextrin derivatives with one to four 2-O-formylmethyl groups attached to the secondary rim were prepared and investigated as catalysts for the oxidation of aminophenols in buffered dilute hydrogen peroxide. The derivatives were found to be Michaelis–Menten catalysts and to give rate accelerations of up to 20,000 for the oxidation of 2-aminophenol to 2-amino-phenoxazin-3-one, and 12,000 for the oxidation of 2-amino-p-cresol to 2-nitro-p-cresol. While a range of differently substituted substrates was oxidized the success of the reaction was highly dependent on the substituent pattern. The ability of one of the new artificial enzymes to oxidize selectively one aminophenol from a mixture of two was investigated giving substrate selectivities of up to 16:1.     

Multicomponent Synthesis of Isoindolinone Frameworks via RhIII‐Catalysed in situ Directing Group‐Assisted Tandem Oxidative Olefination/Michael Addition

A Rh^III‐catalysed three‐component synthesis of isoindolinone frameworks via direct assembly of benzoyl chlorides, o‐aminophenols and activated alkenes has been developed. The process involves in situ generation of o‐aminophenol (OAP)‐based bidentate directing group (DG), Rh^III‐catalysed tandem ortho C?H olefination and subsequent cyclization via aza‐Michael addition. This protocol exhibits good chemoselectivity and functional group tolerance. Computational studies showed that the presence of hydroxyl group on the N‐aryl ring could enhance the chemoselectivity of the reaction.     

Probing interactions between core-electron transitions by ultrafast two-dimensional x-ray coherent correlation spectroscopy

Two-dimensional x-ray correlation spectra (2DXCS) obtained by varying two delay periods in a time-resolved coherent all-x-ray four-wave-mixing measurement are simulated for the N 1s and O 1s transitions of aminophenol. The necessary valence and core-excited states are calculated using singly and doubly substituted Kohn-Sham determinants within the equivalent-core approximation. Sum-over-states calculations of the 2DXCS signals of aminophenol isomers illustrate how novel information about electronic states can be extracted from the 2D spectra. Specific signatures of valence and core-excited states are identified in the diagonal and off-diagonal peaks arising from core transitions of the same and different types, respectively.     

Laccase‐Mediated Synthesis of Novel Substituted Phenoxazine Chromophores Featuring Tuneable Water Solubility

Laccases are members of the blue copper oxidases family found in nature. They commonly oxidise a wide range of phenol and aniline derivatives, which in turn are involved in oxidative coupling reactions. Yet, laccases remain rarely described as biocatalysts in organic synthesis. This paper describes the chemical preparation of original sulfonated aminophenol substrates and their enzyme‐mediated dimerisation into phenoxazine chromophores that feature tuneable water solubility as a function of the sulfonyl substituent. The scope and limitations of the biocatalysed synthetic process are outlined. Kinetic data were collected to evaluate the influence of physicochemical parameters. The structure of the novel phenoxazine dyes (“head‐to‐head” or “head‐to‐tail” dimer) was assessed by NMR spectroscopic analysis. Two crystalline compounds were analysed by X‐ray diffraction. Such laccase‐mediated synthesis (a green chemistry process) was proven to be more efficient than the chemical oxidation of o‐aminophenols with silver oxide.     

Kinetics and selectivity of permanganate chemiluminescence: a study of hydroxyl and amino disubstituted benzene positional isomers

Examination of the chemiluminescence reactions of dihydroxybenzenes, aminophenols and phenylenediamines with acidic potassium permanganate has provided a new understanding of the relationships between analyte structure, reaction conditions, kinetics of the light-producing pathway and emission intensity, with broad implications for this widely utilised chemiluminescence detection system. Using a permanganate reagent prepared in a polyphosphate solution and adjusted to pH 2.5, large differences in the rate of reaction with different positional isomers were observed, with the meta-substituted forms reacting far slower and therefore exhibiting much lower chemiluminescence intensities in flow analysis systems. The preliminary partial reduction of permanganate to form significant concentrations of Mn(III) increased the rate of reaction with all analytes tested, resulting in comparable or (in the case of aminophenol and phenylenediamine) even greater emission intensities for the meta-isomers, demonstrating the opportunity to tune the selectivity of the reagent towards certain classes of compound or even specific positional isomers of the same compound. Using more acidic permanganate reagents, in which polyphosphates are not required, the discrepancy between the chemiluminescence intensities was still observed, but was less prominent due to the generally faster rates of reaction. The enhancement of these chemiluminescence reactions by on-line addition of formic acid or formaldehyde can in part also be attributed to the generation of significant pools of the key Mn(III) precursor to the emitting species.     

Method for determination of polycyclic aromatic hydrocarbons by fluorodensitometry

A TLC fluorodensitometric method for the determination of total PAHs in aqueous and hydroalcoholic solutions at the parts per billion level has been developed. The PAHs are extracted into cyclohexane and separated as a class on a chemically bonded reversed-phase TLC plate using stepwise development. In the fluorescence scanning of the plate the PAHs are located by reference to a mixture of 16 PAHs designated by EPA as primary pollutants and measured as benzo(a)pyrene.     

Migration behavior and separation of benzenediamines, aminophenols and benzenediols by capillary zone electrophoresis

The migration behavior and separation of five benzendiamines, five aminophenols and three benzenediols were investigated in capillary zone electrophoresis. The results indicate that benzendiamines and aminophenols are optimally separated with a phosphate buffer at pH 5, whereas benzenediol isomers are best separated at pH about 12. The addition of surfactant monomers of tetradecyltrimethylammonium bromide to a phosphate buffer at pH 5 under the conditions of reversed electroosmotic flow is effective for separating these dye intermediates, except for the separation of 1,2-benzenediol from 1,3-benzenediol. The addition of sodium tetraborate as an electrolyte modifier is effective in the separation of 1,2-benzenediol from 1,3-benzenediol, but the latter comigrates with the 1,4-benzenediol isomer at pH 5.0. The electrophoretic mobility of ionized analytes can be described with Offord's equation, and the migration order depends on their ratios of charge to mass. In addition, the pKa values of these analytes in 50 mM phosphate buffer are reported.     

Analysis of gardenia blue in foods by thin-layer chromatography

In the present study, a thin-layer chromatography (TLC) method for the analysis of gardenia blue was described. Gardenia blue is obtained from the fruits of Gardenia augusta Merrill or Gardenia jasminoides Ellis. Recently, gardenia blue has frequently been used in Japan as a natural coloring in various foods. However, the structural characterization of gardenia blue components has not been yet clarified and even chromatographic separation of the components has not been reported. Synthetic colors in foods are generally analyzed by TLC; so, we therefore investigated the analysis of gardenia blue in foods with TLC. We established two TLC conditions; reversed phase C-18 TLC using a solvent system of aqueous 0.2% TFA–acetonitrile–ethanol (1:2:3) and TLC on cellulose plate using a solvent system consisting of acetone–3-methyl-1-butanol–water (6:5:5). Both conditions yielded three well-delineated spots with good separation. We applied these separations to the analyses of gardenia blue in coloring matter preparations from different manufacturers and in foods on the market. After the gardenia blue was extracted from the samples with water, the extract was evaporated and the residue was dissolved in water–methanol (1:1). Aliquots of the dissolved solutions were then applied to TLC and their chromatographic behaviors were observed. Each preparation showed characteristic spot patterns depending on the manufacturers. The R_f values of the separated spots when extracted from foods are slightly different from the R_f values of the spots observed for standards, and we were thus able to identify the manufacturers using the spot pattern of gardenia blue. The present study is considered to be useful for the establishment of a method of analysis for gardenia blue in coloring preparations and foods.     

苦荞叶片中芸香甙的薄层色谱定量研究

根据芸香甙的理化性质，建立了一种测定植物样品中芸香甙含量的薄层紫外扫描法，采用硅胶ＧＦ２５４薄层板，样品经甲醇提取浓缩后点样，展开剂为乙酸乙酯－甲酸－水（８＋１＋１）。用薄层色谱扫描仪在波长３５５ｎｍ处测定芸香甙的吸收强度并直接定量。该法操作简便，灵敏度高，定量准确，结果稳定，应用于苦荞叶片中芸香甙含量测定，得到良好结果，线性范围为０～２．０μｇ／μＬ，斑点的最低检出限为５．０ｎｇ，回收率１０２％     

Separation of peptides on Empore thin-layer chromatography sheets and blotting onto polyvinylidene difluoride membranes with subsequent gas phase sequencing.

Methods for the separation of peptides on a new type of thin-layer chromatography (TLC) sheet and blotting onto polyvinylidene difluoride (PVDF) membranes with subsequent gas phase sequencing are described. For validation, the A and B chain of insulin were chromatographed on Empore TLC sheets and either extracted or blotted onto PVDF membranes. The advantages and disadvantages of thin-layer chromatography on Empore sheets versus high performance liquid chromatography (HPLC) are discussed, along with the possibility of combining the two methods. In addition, TLC was combined with electrophoresis (fingerprinting) for the separation of complex peptide mixtures. Blotting from TLC sheets onto PVDF membranes was performed in two ways: contact diffusion and electrophoretic transfer. In our experiments electroblotting was more effective. Amino acid sequence determination of the B chain of insulin was possible both after extraction from the TLC sheet and after blotting onto PVDF membranes. In the former case, liquid phase sequencing and, in the latter case, gas phase sequencing was performed. The possibility to blot from TLC sheets onto membranes, e.g. PVDF, may prove useful in many fields, for example in biochemistry, and in molecular and cell biology.     

Determination of composition distribution of acrylonitrile-styrene copolymers by thin-layer chromatography

Determination of chemical composition distribution of acrylonitrile-styrene copolymers was carried out by thin-layer chromatography (TLC). A mixture of benzene and methyl ethyl ketone gave the most suitable calibration curve of R_f values versus acrylonitrile (AN) contents, where a concentration gradient technique was applied for development. Average AN contents obtained by TLC are coincident with those found by elemental analysis. The copolymers extracted from ABS resins are sufficiently arranged in the order of breadth of composition distribution by using the data from TLC. The agreement between the composition distribution curve and that from the theory of copolymerization is good.     

Sensitive and Selective Spectrophotometric Determination of Para- and Ortho- Aminophenol with Hypochlorite-Alkaline Phenol (Berthelot) Reagents

Abstract

A highly selective and sensitive method is described for the determination of para- as well as ortho-isomers of aminophenol. The method involves oxidative coupling of aminophenol with Berthelot hypochlorite-alkaline phenol reagents. The reaction yielded a blue chromophose with p-aminophenol (∑=10,000 at 633 nm) and a dark green chromophore with o-aminophenol (∑=1436 at 845 nm). The reaction mechanisms involved in the chromophore formation are discussed.     

Clauson–Kaas-Type Synthesis of Pyrrolyl-phenols,from the Hydrochlorides of Aminophenols,in the Presence of Nicotinamide

A facile Clauson–Kaas-type pyrrolyl-phenol synthesis has been achieved in the presence of nicotinamide, which is inexpensive and nontoxic. The starting material is aminophenol hydrochloride. This is advantageous in certain cases because it is the only isolatable form of the corresponding aminophenol.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]