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1.
研究了阳离子表面活性剂溴化十二烷基吡啶(DPB)的吸附和表面胶团化对二氧化硅(CAB-O-SIL)悬浮液稳定性的影响,以及加入电解质的效应.结果表明:DPB在CAB-O-SIL上的吸附等温线呈双平台(或LS)型,溴化钠(0.1mol/L)的存在使吸附等温线向低浓区移动,第二平台的饱和吸附量增大,但基本不影响第一平台的吸附量,这些结果都与涉及形成表面胶团的二步吸附模型相符.当DPB浓度很低时,CAB-O-SIL悬浮液的稳定性随DPB浓度的增大而下降;当DPB浓度增至smc(临界表面胶团浓度)附近时,悬浮液稳定性急剧提高.NaBr的存在,并不影响上述悬浮液稳定性规律.利用表面活性剂的二步吸附和颗粒相互作用模型,并结合DPB吸附等温线的研究结果,可以合理地解释CAB-O-SIL悬浮液稳定性的实验结果.  相似文献   

2.
赵振国  钱程 《应用化学》1998,15(6):6-10
研究了水溶液中十二烷基苯磺酸钠(SDBS)、溴代十四烷基吡啶(TPB)和聚乙烯吡咯烷酮(PVP)在ZrO2上的吸附及对ZrO2水悬浮体稳定性的影响。结果表明:pH=2.4时SDBS在ZrO2上的吸附等湿线为LS型,pH=7.0时TPB的吸附等温线为S型,吸附等温线与ZrO2粒子ζ电势变化同线有大体一致的关系。在最大吸附量时ZrO2粒子ζ电势较大,且吸附的表面活性剂离子形成大部分亲水基朝向水相的表面  相似文献   

3.
PNPAR—CTMAB光度法测定水中痕量阴离子表面活性剂   总被引:1,自引:0,他引:1  
本文研究了对硝基偶氮间苯二酚(PNPAR)与溴化十六烷基三甲铵(CTMAB)形成的离子缔合物PNPAR-CTMAB作显色剂与阴离子表面活性剂(AS)的显色反应,发现在pH13.0的NaOH介质中,AS能定量置换出PNPAR-CTMAB中的PNPAR,而使其最大吸收波长630nm处吸光度下降,阴离子表面活性十二烷基苯磺酸钠(SDBS)和十二烷基磺酸钠(SDS)的ε值分别为3.5×10^4,5.8×1  相似文献   

4.
用表面增强拉曼光谱研究BMAT对不锈钢的缓蚀机理   总被引:1,自引:0,他引:1  
查英华  田中群 《电化学》1995,1(2):152-158
应用表面增强拉曼散射光谱(SERS)技术,研究0.5%HCl体系中缓蚀剂在18-8不锈钢表面的吸附。谱图是在不锈钢表面电沉积不连续Ag颗粒条件下测得的。缓蚀剂BMAT通过电极表面与缓蚀剂中的N原子,以及苯并咪唑环的共轭大π键形成化学吸附,BMAT斜卧于电极表面。其烯丙基起到空间的阻碍的作用。  相似文献   

5.
DSC和FTIR测试表明,结晶/非晶共混体系聚(β-羟基丁酸酯)(PHB)/聚双酚A羟基醚(PBHE)是部分相容的.熔融结晶退火可以大大提高共混物的结晶度,增加其相容性,75/25组分PHB相结晶度最大,50/50组分(020)、(130)晶面微晶尺寸最大.SAXS研究表明,纯PHB的中间层约为1.5nm,片层厚约4.0nm;共混物的中间层在2.0nm左右,片层厚在5.0—7.2nm之间,50/50组分片层最厚.75/25组分晶相和非晶相的密度差最大.  相似文献   

6.
在表面活性剂存在下用5—Br—PADAP吸光光度法测定汞   总被引:7,自引:0,他引:7  
研究了在阴离子表面活性剂SDS存在下,用5-Br-PADAP测定汞的最佳条件。试验表明,在硼砂-盐酸缓冲介质中,PH为8.35 ̄10.40时,络合物的最大吸附波长为λmax=562nm,表观摩尔吸光系数为1.12×10^5,络合物的组成为Hg(Ⅱ):5-Br-PADAP=1:2,线性范围为0 ̄35μg/25ml.方法体系简单,操作方便,是目前光度法测定痕量Hg(Ⅱ)灵敏度较高的方法之一。  相似文献   

7.
盐酸溶液中阴离子表面活性剂在铝表面上的吸附   总被引:2,自引:0,他引:2  
用失重法研究了盐酸溶液中阴离子表面活性剂十二烷基磺酸钠(DSASS),十二烷基苯磺酸钠(DBSAS)以及十二烷基硫酸钠(SDS)在铝表面上的吸附作用,提出这种吸附作用与铝的失重量有关,且符合Lang-muir方程,计算出吸附热,吸附熵和吸附自由能等热力学参数。认为这种吸附主要靠静电作用,根据接触角的变化讨论了阴离子表面活性剂分子在铝表面上的吸附取向。  相似文献   

8.
首次观测到Ag2CO3溶胶体系中的吸附分子(对氨基苯甲酸PABA)表面增强拉曼散射(SERS)效应特强,该体系对PABA的增强程度比Ag胶还强。同时,分别向该体系加入少量的S2O3,Fe(CN)6,H2O2和NO3-溶液后,观测其对PABA的SERS谱带强度的影响,探讨该体系的增强机制。结果表明,胶体表面的Ag+或Agδ+是该体系的SERS活位吸附点,而表面络合物对其SERS起到一定的作用。  相似文献   

9.
研究了SACF-Mn对乙基硫醇的吸附性能。发现SACF-Mn对乙基硫醇的吸附性能与SACF-Mn的制备条件密切相关.SACF-Mn对乙基硫醇的吸附,特别对汽油中硫醇的吸附性能优异于SACF.  相似文献   

10.
AB—8树脂对罗汉果皂甙的吸附   总被引:5,自引:0,他引:5  
本文初步研究了大孔吸附树脂AB-8对罗汉果皂甙的吸附性能,比较了15℃和65℃下的吸附速度,获得了在SV2、SV5、SV8三种空速下的穿漏吸附量。  相似文献   

11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

12.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

13.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

14.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.  相似文献   

15.
16.
《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.  相似文献   

17.
Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.  相似文献   

18.
A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.  相似文献   

19.
A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).  相似文献   

20.
Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO4 oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.  相似文献   

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