共查询到20条相似文献,搜索用时 234 毫秒
1.
2.
3.
用400MHz超导核磁共振波谱仪测定了X取代苯甲酰苯胺(X=p-NO2,p-Cl,p-Br,p-1,H,p-CH3,p-OCH3,m-CH3)的1H和13C NMR谱,按双参数方程进行计算,结果表明N-1H,羰基碳,与羰基相连的苯环碳和与氮相连的苯环碳等碳原子的化学位移与取代基共轭效应参数σR和诱导效应参数σI间的良好的线性关系。测得了双参数方程中适用于苯甲酰苯胺衍生物的3个常数a、b和c的值以及σR、σI的权重。 相似文献
4.
三苯基锡苯氧乙酸酯化合物的13C NMR研究 总被引:1,自引:1,他引:0
测定了14种三苯基锡苯氧乙酸酯化合物的13CNMR谱,利用模型化合物对比及化学位移计算比较等方法.对全部谱线进行了归属,确定了化合物的分子结构.首次求得对苯环碳的取代基化学位移值(SCS):Cipso=30.2,Cortho=-13.5,Cmeta=1.0,Cpara=-7.5. 相似文献
5.
6.
7.
本文测定了新合成的,具有生理活性的1-(4-吡啶甲酰)-4 -苯基氨基硫脲,1-(4-吡啶甲酰)-4-对氯苯基氨基硫脲,1-(4 -吡啶甲酰)-4-对溴苯基氨基硫脲3-(4-吡啶基)-4-苯基-1,2,4,-三唑啉-5-硫酮,3-(4-吡啶基)-4-对氯苯基-1,2,4,-三唑啉-5-硫酮,3-(4-吡啶基)-4-对溴苯基-1,2,4-三唑啉-5-硫酮六个新化合物的~(13)C-NMR谱,并通过~(13)C-NMR谱中的宽带去偶,偏共振及APT技术,模型化合物对照,讯号强度对比及芳基取代基常数计算等方法,进行了上述化合物~(13)C-NMR谱峰的归属,并得到了甲酰肼基在吡啶环4位取代后对吡啶环各碳所产生的取代基效应. 相似文献
8.
通过非环前体的分子内成环反应,可合成一类多取代苯,对这类产物进行结构鉴定,有助于了解整个反应历程和机理。但取代基增多,势必导致各结构因素变得复杂,难以从各芳碳的经验计算式去推测各取代基所处的相对位置,而以一般的光、波谱方法也较难获得这类结构信息。实验表明,核磁COLOC技术是确定这类产物各取代基相对位置较为合适的方法,本文以NMR技术对这类产物进行了结构鉴定,并讨论了COLOC技术在确定其各取代基相对位置中的作用;同时通过对产物的结构确认,讨论了产物取代基间的相互作用所导致其芳碳化学位移实测值与经验计算值之间的差异,以及含氟基团对邻位芳碳的碳氟间三键偶合作用。 相似文献
9.
核磁COLOC技术在一类多取代苯结构鉴定中的应用一类多取代苯结构的COLOC鉴定 总被引:2,自引:2,他引:0
通过非环前体的分子内成环反应,可合成一类多取代苯,对这类产物进行结构鉴定,有助于了解整个反应历程和机理。但取代基增多,势必导致各结构因素变得复杂,难以从各芳碳的经验计算式去推测各取代基所处的相对位置,而以一般的光、波谱方法也较难获得这类结构信息。实验表明,核磁COLOC技术是确定这类产物各取代基相对位置较为合适的方法,本文以NMR技术对这类产物进行了结构鉴定,并讨论了COLOC技术在确定其各取代基相对位置中的作用;同时通过对产物的结构确认,讨论了产物取代基间的相互作用所导致其芳碳化学位移实测值与经验计算值之间的差异,以及含氟基团对邻位芳碳的碳氟间三键偶合作用。 相似文献
10.
该文对1,2-取代乙烯衍生物的化学结构的NMR测定方法进行了研究. 结果表明,多频率位移激发双梯度自旋回波1D NOE新方法用于阐明这类化合物的化学结构具有独到之处. 强偶合自旋体系信号的选择性粒子数转移 (SPT)影响可得到有效抑制,NOE信号为吸收型,微小(约0.8%)的NOE信号也可明确测定,重叠复杂的谱峰可分离和辨认,测定顺反异构体不需要标准样品对照,结果准确、可靠. 该文以2-甲氧基-4-(2-苯基-2-环己基氨基甲酰基-乙烯基)-乙酸苯酯为例,阐明1D NOE方法在1,2-取代乙烯衍生物的化学结构和立体化学研究中的应用. 相似文献
11.
Evaluation by empirically derived equations for the Substituent effect (α, β, γ, δ) on the 13C NMR chemical shifts for C-3, C-4. C-5 and halomethyl-substituent carbon (C-6) in isoxazoles 1-5 [where C-3 substituent (R1) = H, alkyl or phenyl, C-4 Substituent (R2) = H, alkyl, and C-5 substituent (R3) = di-or trihalomethyl, methyl and H], taking as reference the compound la, is reported. From the calculated values for the α, β, γ, δ effects for each substituent it was possible to estimate the chemical shift of each carbon of the compounds 1–5. The 13 C chemical shifts of the C-3, C-4, C-5, C-6 of these compounds, can be estimated with good precision: 94% of the calculated chemical shifts are found to be within ±1.0ppm, and 100% are found to be within ±1.5ppm. 相似文献
12.
13.
Evaluation by empirically derived equations for the substituent effect (α,β,γ,δ) on the 13C NMR chemical shifts for C-1, C-2, C-3 and C-4 in β-aryl-β-methoxyvinylhalomethylketones 1a-g to 2a-g [R3C(O)-CH=C(Ar)-OMe, where R3 = CCl3, CF3 and Ar = p-YC6H4 (Y = H, Me, MeO, F, Cl, Br, NO2)], taking as reference the β-ethoxyvinyltrichloromethylketone (3), is reported. From the calculated values for the α,β,γ,δ effects for each substituent it was possible to estimate the chemical shift of each carbon of the compounds 1,2. The 13C chemical shifts of the C-1, C-2, C-3, C-4 of these compounds, can be estimated with good to rasoable precision: 84% of the calculated chemical shifts are found to be within ±1.0ppm, and 100% are found to be within ±1.5ppm. The Y-Effects on C-3 and C-4 are compared with carbon charge densities (qr). 相似文献
14.
15.
16.
取代基效应(SCS)与乙烯—α—烯烃共聚物的序列结构:Ⅰ,乙烯—丙烯共聚物 总被引:7,自引:3,他引:4
本文应用取代基效应方法处理乙丙共聚物的~(13)C NMR谱,第一次得到这个共聚物(CH_3)的取代基参数,在此基础上归属了乙丙共聚物的~(13)C谱,讨论了共聚物序列结构的几种表示方法,进而用一套普适的公式计算了几个共聚物的序列分布,并作了比较。 相似文献
17.
Evaluation by empirically derived equations for the substituent effect (EXn and EYn, n = 1 to 6) on the 13C NMR chemical shifts for C-1, C-2, C-3, C-4, C-5 and C-6 in 1-alkylamino-6-ethoxy-1,5-hexadien-3,4-diones 1a-f and 1,6-bis(alkylamino)-1,5-hexadien-3,4-diones 2a-f [XCH=CHC(O)-C(O)CH=CHY, where X, Y = OEt, NH2, PhCH2NH, n-BuNH, i-PrNH, cyclo-C6H11NH, t-BuNH], taking as reference the 1,6-diethoxy-1,5-hexadien-3,4-dione (3), is reported. From the calculated values for the EXn and EYn effects for each substituent it was possible to estimate the chemical shift of each carbon of the compounds 1,2 with excellent precision: 100% of the calculated chemical shifts are found to be within ±0.5ppm. The carbon-13 chemical shifts of C-1, C-2 and C-3 of compounds 1a,2a,3 led a good correlation with carbon charge densities (qr). 相似文献
18.
取代基效应(SCS)与乙烯-α-烯烃共聚物的序列结构Ⅱ.取代基效应方法 总被引:3,自引:2,他引:1
本文提出了一种解析乙烯-α-烯烃共聚物的13C NMR谱的取代基效应方法,它揭示了存在于共聚物序列结构与13C谱之间的对应关系,并对这种关系进行了系统的阐述。文章中首次按上述对应关系明显与否将共聚物13C谱分成两类,并给出进行分类的三种判据:SCS参数,共单体均聚物的13C谱,以及取代基的电性。文章最后比较了取代基效应方法与Grant-Paul方法的异同。 相似文献
19.
The first 2D-NMR study on bis(amidinohydrazones) [‘(guanylhydrazones)’] is reported. Heteronuclear shift correlation (HETCOR) experiments were performed on the enzyme inhibitors methylpropylglyoxal bis(amidinohydrazone) (MPGBG) and butylmethylglyoxal bis(amidinohydrazone) (BMGBG). The results obtained made possible the unambiguous assignment of the previously unassigned resonances of the side-chain carbon atoms of MPGBG. The results indicate that the chemical shifts of the protons of the propyl side chain of MPGBG are positively correlated to the 13C chemical shifts of the corresponding carbon atoms. The chemical shifts of the carbon atoms of the propyl side chain decrease as a function of the position of the atom in the side chain, the terminal methyl group having the lowest shift value. These results are in full agreement with previous results on the analogous compound dipropylglyoxal bis(amidinohydra- zone), whose side-chain carbon resonances were assigned using totally different techniques. In the case of BMGBG, however, HETCOR contour plots clearly indicate that there is no correlation between the chemical shifts of the protons of the butyl side chain and the 13C chemical shifts of the corresponding carbons. Because the 200 MHz proton spectrum of BMGBG is not fist-order, only the 1 3 resonance~ of the methyl substituent and the resonances of carbons 1 and 4 (but not those of carbons 2 and 3) of the butyl side chain could be assigned on the basis of the HETCOR study. Yet, the results gave a rough estimate of the previously unknown chemical shifts of the protons bound to butyl carbon atoms 2 and 3. 相似文献
20.
Marcos A.P. Martins 《光谱学快报》2013,46(4):631-640
Abstract Evaluation by empirically derived equations for the Substituent effect (α, β, γ, δ) on the 13C NMR chemical shifts for C-2, C-3, C-4, C-5, C-6, the halomethyl-substituted carbon (C-7) and the cyano or oxymic carbon (C-8) in 2-halomethyl-2-hydroxy-tetrahydrofurans 1a-c, 2, 3a, b, 4a and -5,6-tetrahydro-4H-pyrans 5a-c, 6a [with C-2-substituents (R2): CF3, CCl3 or CHCl2, C-3-substituents (R3): CN, C(Me)=NOH, CH=NOMe, C(Me)=NOMe or CH=NOH], taking as reference the 2-trifluoromethyl-2-hydroxy-tetrahydrofuran (la), is reported. From the additivity properties of the α-, β-, γ-, δ-and ?-effects for each Substituent it is possible to predict the chemical shift of each carbon of the compounds 1–6. 相似文献