同位素稀释-超高效液相色谱-串联质谱法测定化妆品中香兰素和乙基香兰素

建立同位素稀释-超高效液相色谱-串联质谱法同时测定化妆品中两种香兰素类香料的方法。取1 g样品，加入50μL质量浓度均为1 mg/L的香兰素-D3、乙基香兰素-D5混合同位素内标溶液，以甲醇为提取溶剂，溶解后定容至10 mL，在室温下超声提取15 min，离心分离后，取1 mL上清液用氮气吹干，再用1 mL 0.1%甲酸水溶液-甲醇(体积比为80∶20)定容，过滤后上机分析。经RRHD Eclipse Plus C₁₈色谱柱分离后，使用ESI源对目标物进行电离，在多反应监测模式下绘制色谱图，内标法定量。在5～100μg/L范围内，香兰素、乙基香兰素与内标的质量浓度比与对应色谱峰面积的比线性关系良好，相关系数均大于0.999，方法检出限均为5μg/kg。空白样品加标回收率分别为87.8%～96.1%、80.1%～83.8%，测定结果的相对标准偏差分别为2.5%～3.8%、1.7%～4.6%(n=6)。该方法操作简便，可满足同时测定化妆品中两种香兰素类香料的要求。     

Nafion-石墨烯修饰电极溶出伏安法测定巧克力中的乙基香兰素

采用Nafion-石墨烯修饰电极差分脉冲溶出伏安法测定巧克力中乙基香兰素的含量。于pH 1.98的B–R缓冲溶液中,在0.83 V电压下将巧克力样品溶液搅拌富集60 s,获得一个灵敏的阳极溶出峰,峰电流与样品溶液的质量浓度线性相关,线性范围为2.4~8.2μg/mL,相关系数为0.999 5,测定结果的相对标准偏差为1.60%(n=15)。乙基香兰素的检出限为0.076μg/mL,加标回收率为98.60%~101.38%。该方法可用于食品中乙基香兰素含量的测定。     

HPLC法同时测定烟用添加剂中的香兰素、乙基香兰素、麦芽酚和乙基麦芽酚

建立了同时测定烟用添加剂中香兰素、乙基香兰素、麦芽酚和乙基麦芽酚的高效液相色谱检测方法。样品经稀释剂稀释、振荡、过滤后,采用Thermo Scientific C18(4.6 i.d×250 mm,5μm)柱,以V(乙腈)∶V(0.1%甲酸水溶液)=33∶67为流动相,在流速1.0 mL/min条件下等度洗脱分离,在波长为273 nm下以二极管阵列检测器检测,以外标法定量。结果表明,9 min内即可实现4种目标物的分离,香兰素、乙基香兰素、麦芽酚和乙基麦芽酚的线性范围分别为0.0139~264.5 mg/kg,0.0554~302.7 mg/kg,4.01~262.9 mg/kg和2.32~258.1 mg/kg;线性相关系数分别为0.9998,0.9999,0.9999和0.9997;检出限(S/N=3)分别为0.00349,0.00554,1.29和0.58 mg/kg;添加水平为10.75~59.14 mg/kg时,加标回收率为96.8%~102.2%,相对标准偏差为0.62%~1.6%。方法适用于烟用添加剂中香兰素、乙基香兰素、麦芽酚和乙基麦芽酚的含量检测。     

气相色谱-质谱法测定烟用香精香料中香兰素和乙基香兰素

采用气相色谱-质谱法测定烟用香精香料中香兰素和乙基香兰素的含量。烟用香精香料样品与萃取剂的比例为1g比100mL,在500W下超声萃取10min。在气相色谱分离中用DBWAXETR毛细管柱为固定相,在质谱分析中采用选择离子监测模式。以丙酸苯乙酯为内标物。香兰素和乙基香兰素的线性范围均为0.5~200mg·L-1,检出限(3S/N)分别为0.03,0.02mg·kg-1。加标回收率在91.4%~109%之间,测定值的日内相对标准偏差(n=5)在0.43%~2.2%之间,日间相对标准偏差(n=5)在0.67%~2.6%之间。     

固相萃取-气相色谱/质谱联用法测定卷烟主流烟气中的香兰素和乙基香兰素

采用固相萃取-气相色谱/质谱联用技术,建立了一种同时测定卷烟主流烟气中香兰素和乙基香兰素的方法。方法优化了萃取条件,考察了萃取溶剂、萃取时间对检测结果的影响。通过硅藻土固相萃取柱净化并浓缩后,选取DB-HeavyWAX毛细管柱进行目标物分离,以香兰素-d3作为内标,对香兰素和乙基香兰素进行定量分析。结果表明,香兰素和乙基香兰素在浓度0.2~20.0 mg/L范围内具有良好的线性关系,其检出限分别为9.1 ng/支和6.5 ng/支,回收率均在96.3%~107.7%之间。     

发酵液中香兰素的反相高效液相色谱分析方法研究

建立了测定发酵液中香兰素含量的反相高效液相色谱方法。采用Symmetry C18柱(5μm,4.6 mm i.d.×150 mm),以V(甲醇)∶V(水)=35∶65为流动相,流速为1.0 mL/min,紫外检测波长为280 nm,柱温为室温,进样量10μL。香兰素在5.0~1000 mg/L范围内,峰面积与质量浓度呈良好的线性关系,相对标准偏差RSD为0.68%,回收率在99.88%~100.28%之间。该方法适用于微生物发酵法合成香兰素的质量控制及发酵工艺的改进。     

高效液相色谱法同时测定香兰素与邻位香兰素

建立了同时测定香兰素和邻位香兰素的高效液相色谱法.考察了流动相组成、柱温等因素对分析效率的影响.在流动相为5% 乙酸-乙腈(60 :40,体积比),流速1.0 mL/min,柱温25 ℃的优化条件下,香兰素和邻位香兰素可在5 min内实现分离.测定结果表明,香兰素和邻位香兰素在10 ～240 mg/L范围内线性关系良好...     

毛细管区带电泳法同时分离测定香兰素和邻位香兰素异构体

建立了同时测定香兰素和其异构体邻位香兰素的毛细管区带电泳法(CZE)。考察了缓冲溶液的种类、浓度和pH以及分离电压等因素对分离结果的影响。在缓冲溶液为50 mmol/L硼砂-150 mmol/L磷酸氢二钠(pH 7.5)、分离电压15 kV的优化条件下,6 min内即可实现分离。香兰素和邻位香兰素在10～240 mg/L范围内线性关系良好,相关系数分别为0.9999和0.9997;方法的检出限均为1.0 mg/L (信噪比为3);样品的加标回收率为99.4%～101.2%,相对标准偏差为0.19%～0.73%。该方法操作简单、快速,已应用于实际样品的分析,并获得了令人满意的结果。     

超高效液相色谱-串联质谱法同时测定食品中4种常用香精

建立了超高效液相色谱-串联质谱法同时测定食品中香兰素、乙基香兰素、麦芽酚和乙基麦芽酚4种香精的方法。样品用水提取,固相萃取小柱净化,目标化合物采用UPLC^TMBEH C18色谱柱(50 mm×2.1 mm, 1.7 μm)分离,以甲醇和含0.002 mol/L乙酸铵及0.1%(v/v)甲酸的水溶液为流动相进行梯度洗脱,采用电喷雾离子源电离、正离子多反应监测模式质谱检测。4种香精在5~500 μg/L或10~1000 μg/L质量浓度范围内线性良好,相关系数均在0.9995~0.9998之间;回收率为75.8%~116%,相对标准偏差(RSD, n=6)为1.58%~4.01%。该方法灵敏、准确,检测范围广,分析速度快,适合食品中香兰素、乙基香兰素、麦芽酚和乙基麦芽酚4种香精的检测。     

乙基香兰素的合成

本文报道了应用相转移催化技术合成中间体邻乙氧基苯酚及产物乙基香兰素,考察了反应温度、时间、物料配比等因素对合成的影响,确立了优化条件。同时采用 UV,IR,~1HNMR 和 GC方法对产物进行表征。研究结果显示聚乙二醇相转移催化合成邻乙氧基苯酚,叔胺相转移催化合成乙基香兰素结果满意。邻乙氧基苯酚最高收率达74.5%,乙基香兰素最高收率达73.5%。另外,还对反常 Reimer-Tiemann 反应相转移催化合成乙基香兰素的机制进行了讨论。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.