首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
干法制备阳离子淀粉(Ⅰ):反应效率的研究   总被引:11,自引:0,他引:11  
具本植  杨锦宗等 《化学通报》2001,64(11):707-710
在碱催化剂BZ-1存在下,以N-(2,3-环氧丙基)三甲基氯化铵(GTA)为阳离子化试剂,干法制备了高取代度季铵型阳离子淀粉。考察了碱催化剂BZ-1、水含量、反应温度和反应时间对取代度和反应效率的影响。当淀粉用量为5.5g,GTA用量为3g时,最佳反应条件为:碱催化剂BZ-10.8g、反应温度60℃、反应时间4h、反应体系含水量24%,取代度可达0.56,反应效率为88%.  相似文献   

2.
干法制备阳离子淀粉(I):反应效率的研究   总被引:4,自引:0,他引:4  
在碱催化剂BZ-1存在下,以N-(2,3-环氧丙基)三甲基氯化铵(GTA)为阳离子化试剂,干法制备了高取代度季铵型阳离子淀粉.考察了碱催化剂BZ-1、水含量、反应温度和反应时间对取代度和反应效率的影响.当淀粉用量为5.5g,GTA用量为3g时,最佳反应条件为:碱催化剂BZ-1 0.8g、反应温度60℃、反应时间4h、反应体系含水量24%,取代度可达0.56,反应效率为88%.  相似文献   

3.
交联阳离子淀粉(DS=0.95)的干法制备及其脱色性能   总被引:4,自引:0,他引:4  
在碱催化剂BZ-1存在下,以N-(2,3-环氧丙基)三甲基氯化铵(GTA)为阳离子化试剂,干法制备了交联高取代度季铵型阳离子淀粉。对制得阳离子淀粉的脱色性能研究结果表明,交联高取代度阳离子淀粉对活性染料具有优异的脱色效果。  相似文献   

4.
交联阳离子淀粉(DS=0.95)的干法制备及其脱色性能   总被引:2,自引:0,他引:2  
在碱催化剂BZ-1存在下,以N-(2,3-环氧丙基)三甲基氯化铵(GAT)为阳离子化试剂,干法制备了交联高取代度季铵型阳离子淀粉。对制得阳离子淀粉的脱色性能研究结果表明,交联高取代率阳离子淀粉对活性染料具有优异的脱色效果。  相似文献   

5.
活性艳红X-3B水溶液的光化学与光催化协同脱色反应   总被引:30,自引:0,他引:30  
 对影响活性艳红X-3B水溶液光化学与光催化协同脱色反应的各种条件(如溶液的pH值,紫外光照强度,空气流量,催化剂用量及溶液的初始浓度等)进行了考察.结果表明,降解率随着紫外光照强度的增强而加快,随着X-3B初始浓度的增大而减慢;催化剂最佳用量为4g/L,空气最佳流量为4.3L/h.在X-3B水溶液的光催化脱色过程中,存在有光解反应,但它远不如光催化反应重要.因此,活性艳红X-3B水溶液的降解是光化学与光催化的协同脱色反应.  相似文献   

6.
以天然玉米淀粉和月桂酸为原料,脂肪酶Novozym 435为催化剂,研究了微波辐照下月桂酸淀粉酯的酶促合成。通过对淀粉进行预处理活化来提高淀粉的酯化反应活性,并主要考察了微波功率、月桂酸用量、脂肪酶Novozym 435用量及反应时间等参数对酶促月桂酸淀粉酯合成的影响。采用气相色谱法进行取代度的测定,并以取代度为考察指标,确定了最佳的反应条件。结果表明,淀粉的最佳预处理方法为NaOH/尿素混合溶液法,经该法处理后淀粉的酯化反应活性大大提高;微波辐照技术的应用大大缩短了反应时间,并提高了月桂酸淀粉酯的取代度。适宜的工艺条件为:微波功率为240W,月桂酸用量为30%,酶加入量为7%,反应时间26min。在上述反应条件下可以制得取代度为 0.0311的月桂酸玉米淀粉酯。  相似文献   

7.
以天然玉米淀粉和月桂酸为原料,脂肪酶Novozym 435为催化剂,研究了微波辐照下月桂酸淀粉酯的酶促合成.通过对淀粉进行预处理活化来提高淀粉的酯化反应活性,并主要考察了微波功率、月桂酸用量、脂肪酶Novozym 435用量及反应时间等参数对酶促月桂酸淀粉酯合成的影响.采用气相色谱法进行取代度的测定,并以取代度为考察指标,确定了最佳的反应条件.结果表明,淀粉的最佳预处理方法为NaOH/尿素混合溶液法,经该法处理后淀粉的酯化反应活性大大提高;微波辐照技术的应用大大缩短了反应时间,并提高了月桂酸淀粉酯的取代度.适宜的工艺条件为:微波功率为240 W,月桂酸用量为30%,酶加入量为7%,反应时间26 min.  相似文献   

8.
以缩水甘油醚三甲基氯化铵(GTA)和丙烯酸为原料,合成了阳离子丙烯酸酯单体,研究了反应物配比、温度、时间、及催化剂用量对产物酯化率的影响,确定了产物最优合成工艺为:异丙醇作反应溶剂,n(丙烯酸)∶n(GTA)=1.1∶1,反应温度70℃,反应时间6h,此条件下酯化率78%,产物收率86%.产物结构通过红外光谱得以证实.该单体经种子乳液聚合得到阳离子聚丙烯酸酯乳液,与氧化淀粉复配后制备的阳离子表面施胶剂对提高纸张的强度具有明显作用.  相似文献   

9.
Keggin型磷钼钒季铵盐催化氧化苯制苯酚反应研究   总被引:2,自引:3,他引:2  
采用分步反应、分步酸化法制备了磷钼钒缺位型杂多酸,用(C4H9)4N^+(以下简写为Bu4N^+)阳离子取代杂多酸中H^+作为反荷离子合成了杂多季铵盐(用于苯氧化制苯酚反应).FT-IR分析反应前后催化剂结构的变化.以苯为原料,乙酸为溶剂,30%H2O2作氧化剂,系统考察了催化剂类型、催化剂用量、氧化剂用量、反应时间及温度对反应的影响.实验结果表明,56.4mmol苯在(Bu4N)5PMo10V2O40用量0.25mmol,30%H2O2用量10mL,溶剂乙酸10mL,70℃条件下回流反应6h,苯酚收率可达到27.9%.  相似文献   

10.
高效液相色谱法测定烟草料液中的糖、甘油和丙二醇   总被引:10,自引:0,他引:10  
研究了用高效液相色谱法测定烟草料液样品中糖、甘油和丙二醇的方法。烟草料液用Sep-Park-C18固相萃取小柱预分离,以Waters Surar-Pakl钙型阳离子交换柱为固定相,0.05g/L EDTA钙钠水溶液为流动相,示差折光仪为检测器,一次进样测定烟草料液样品中的糖、甘油和丙二醇。线性范围为0.005-5g/L,检测限在1.5-2.5mg/L之间,相对标准偏差为0.89%-1.3%,标准回收率在96.0%-103%之间。方法用于几种烟草料液样品测定,结果令人满意。  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.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

13.
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   

14.
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   

15.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

16.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

17.
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   

18.
19.
《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   

20.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号