内消旋和外消旋2,3-二氰基-2,3-二苯基丁二酸二乙酯对苯乙烯聚合反应的影响

测定了题目化合物立体异构体在80℃和90℃引发苯乙烯的自由基聚合反应.在相同条件下,较活泼的meso-体为引发剂时,聚合速率大,产物分子量小;而较稳定的dl-体则聚合速率小,产物分子量大.且在所有反应条件下分子量均随反应时间增长.研究结果认为它们不同的聚合性能主要与异构体热分解速率对聚合动力学的影响有关.     

(N,N′—二乙基)偶氮二异丁脒盐酸盐引发下的丙烯酰胺水溶液聚合

本文研究了(N,N′—二乙基)偶氮二异丁脒盐酸盐引发下丙烯酰胺水溶液聚合的反应动力学。得出了聚合速率方程式为RP=KP[EAIBA]05[AM]。测定了聚合表观活化能。并研究了聚合条件对产物分子量及其分布的影响。利用该引发—聚合体系,获得了相对分子量上千万超高分子量聚丙烯酰胺。     

用新型水溶性偶氮引发剂引发二甲基二烯丙基氯化铵的聚合反应

偶氮双脒式丙烷二盐酸盐在水介质中引发的二甲基二烯丙基氯化铵聚合，其引发速率较用过硫酸铵引发的快，转化率，分子量也较高。对反应助剂Ｎａ４ＥＤＴＡ和水介质的ＰＨ值对两引发体系的影响进行了研究。计算出在绝热聚合条件下三种引发体系的活化能。     

（N,N‘—二乙基）偶氮二异丁脒盐酸盐引发下的丙烯酰胺水溶液聚合

本文研究了（Ｎ,Ｎ‘－二乙基）偶氮二异丁脒盐酸盐引发下丙烯酰胺水溶液聚合的反应动力学。得出了聚合速率方程式为Ｒｐ＝Ｋｐ「ＥＡＩＢＡ」＾０．５「ＡＭ」．测定了聚合表观活化能。并研究了聚合条件对产物分子量及其分布的影响。利用该引发一聚合体系,获得了相对分子量上千眼高分子量聚丙烯酰胺。     

2,3-二氰基-2,3-二苯基丁酸二乙酯引发苯乙烯的本体 聚合反应

在70～90℃对标题化合物外消旋异构体引发的苯乙烯本体聚合反应进行了研究,并与内消旋异构体、过氧化二苯甲酰和偶氮二异丁腈进行比较。结果表明,在本反应条件下,上述四种引发剂均能使聚合物分子量随反应时间的延续而增大,但C－C键引发剂对聚合物分子量及其链增长的影响远大于BPO和AIBN,这一现象应与α－氰基-α-乙氧甲酰基苄基自由基的结构特点有关。     

2,3-二氰基-2,3-二苯基丁酸二乙酯引发苯乙烯的本体 聚合反应

在70～90℃对标题化合物外消旋异构体引发的苯乙烯本体聚合反应进行了研究,并与内消旋异构体、过氧化二苯甲酰和偶氮二异丁腈进行比较。结果表明,在本反应条件下,上述四种引发剂均能使聚合物分子量随反应时间的延续而增大,但C－C键引发剂对聚合物分子量及其链增长的影响远大于BPO和AIBN,这一现象应与α－氰基-α-乙氧甲酰基苄基自由基的结构特点有关。     

本体溶液法合成超高分子量聚苯乙烯

对２，３－二氰基－２，３－二苯基丁二酸二乙酯引发苯乙烯本体溶液聚合，合成超高分子量聚苯乙烯的宏观动力学进行了研究。结果表明，这种引发剂在苯乙烯中引发聚合性能温和，在一定条件下，随反应时间的增长，聚合产物的分子量不断增高，可形成超高分子量聚合物。     

乙烯-醋酸乙烯酯-α-烯烃三元共聚物

以乙烯、醋酸乙烯酯和α-烯烃为原料,以偶氮二异丁腈为引发剂,通过高压本体聚合制备三元聚合物.考察了聚合条件对共聚物数均分子量和醋酸乙酯(VA)质量分数的影响.结果表明:在引发剂用量为1.1g,反应压力为6 MPa,反应温度95℃,醋酸乙烯酯和α-烯烃的质量比为2:1的条件下能得到数均分子量为8 600和VA质量分数为0.35的产物.实验证明该产物性能优良,可作为蜡的添加剂.     

α,ω-二(4-羟基丁基)二甲基硅氧烷低聚物的制备与研究

以二(4-羟基丁基)四甲基二硅氧烷(HT)为封端化合物,在催化剂四甲基氢氧化铵的催化下,八甲基环四硅氧烷(D4）开环聚合,制得α,ω-二(4-羟基丁基)二甲基硅氧烷低聚物(DMSO)。应用红外光谱、凝胶色谱和旋转粘度计等测试手段,研究了聚合温度、原料(HT和D4)配比以及催化剂除去方式等工艺条件对聚合反应和聚合产物分子量的影响。研究结果表明,聚合反应温度对聚合产物分子量没有明显的影响;HT为封端化合物,在聚合过程中起止链剂的作用,其在原料中所占比例越大,DMSO分子量越小,原料中D4含量越大,DMSO分子量越大;聚合反应完成后,应采用洗涤法去除催化剂,否则由于端羟基发生去水反应而失去端羟基,致使产率下降,甚至得不到预期的产物。研究表明DMSO通过端羟基形成氢键而聚集,使其黏度升高。DMSO分子量越小,氢键缔合作用越大。     

四乙基二氟化氢铵催化的基团转移聚合

用三种引发剂进行了二氟化氢负离子催化的基团转移聚合,得到了窄分布的,实测分子量和理论分子量相近的一系列聚甲基丙烯酸酯产物,合成了分子量达20万以上的聚甲基丙烯酸甲酯,探讨了引发剂和催化剂用量对产物的分子量和分散性的影响,认为过量的催化剂使产物的分散性加大和实测(?)_n大于理论M_n。得到了控制聚合的最佳催化剂和引发剂浓度比。     

Alternating copolymers of styrene with tricyanoethylene and ethyl 2,3-dicyanoacrylate

Ethyl 2,3-dicyanoacrylate was prepared from ethyl 2,3-dicyanopropionate. High molecular weight, 1:1 alternating copolymers of styrene with tricyanoethylene and ethyl 2,3-dicyanoacrylate were prepared by bulk polymerization with the use of free-radical initiators. Solution polymerization of styrene with ethyl 2,3-dicyanoacrylate in acetonitrile gave the highest molecular weight copolymer (η_inh = 0.74). The copolymers showed unusual thermal properties, i.e., an initial break that was 50–75°C lower than that of polystyrene followed by the formation of an intermediate product that was fairly stable to approximately 500°C.     

N-苯基-双环[2.2.1]庚-5-烯-2,3-二甲酰亚胺的热聚合反应

以核磁共振波谱和溴加成法分析N-苯基-双环[2.2.1]庚-5-烯-2,3-二甲酰亚胺的聚合物的化学结构。聚合物分子具有含内、外式双环[2.2.1]庚-5-烯双键和环戊烯双键的结构单元。半定量地测定了各类双键的含量。分子的饱和链段有5,7-位相连的外式构型和5,6-位相连的内式构型的双环[2.2.1]庚烷的结构单元。结果表明,聚合过程中有构型的转变,重排反应,以及不同的链增长途径。     

Stereoregular fluoropolymers: 6. The ring-opening polymerization of N-pentafluorophenylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide

Exo-N-pentafluorophenylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide(I) readily undergoes metathesis ring-opening polymerization when exposed to conventional metathesis catalysts such as WCl₆/ME₄Sn and MoCl₅/Me₄Sn; by contrast, its endo isomer (II) is not homopolymerized but can be copolymerized with (I). The microstructures of the resulting polymers are established and discussed.     

“Living” radical polymerization of methyl methacrylate with diethyl 2,3-dicyano-2,3-diphenylsuccinate as a thermal iniferter

The bulk polymerization of methyl methacrylate (MMA) initiated with diethyl 2,3-dicyano-2,3-diphenylsuccinate (DCDPS) was studied. This polymerization showed some “living” characteristics; that is, both the yield and the molecular weight of the resulting polymers increased with reaction time, and the resultant polymer can be extended by adding MMA. The molecular weight distribution of PMMA obtained at high conversion is fairly narrow (M_w/M_n = 1.24≈1.34). It was confirmed that DCDPS can serve as a thermal iniferter for MMA polymerization by a “living” radical mechanism. Furthermore, the PMMA obtained can act as a macroinitiator for radical polymerization of styrene (St) to give a block copolymer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4610–4615, 1999     

Relative stabilities of some synthetically useful 2,3-cis-disubstituted aziridines and their 2,3-trans isomers

The relative stabilities of synthetically useful 2,3-cis/trans pairs of 2,3-disubstituted aziridines were investigated theoretically by performing molecular orbital calculations at the MP2/6-31G**/RHF/6-31G** level of theory. The results showed clearly that a functional group on the nitrogen atom of the aziridine ring plays a very important role in conjunction with the relative stabilities of these pairs of isomers. There is a tendency that the 2,3-cis isomer bearing tetrahedral structure on the aziridine nitrogen is preferable. Bulky substituents such as a phenyl group on aziridine atoms can also affect the relative stability sterically.     

Identification of 2,3-dimethyl-2,3-diisobutyl succinonitrile in laser printer emissions

2,3-Dimethyl-2,3-diisobutyl succinonitrile was identified as the main volatile organic compound (>90%) emitted from laser printers during the printing process. Experiments were carried out in a large environmental chamber of 30 m3, where the printers were placed and working simulating 'real office setting' conditions. Air samples were taken on Tenax TA adsorbent cartridges in the vicinity of the printers and further analyzed by thermal desorption gas chromatography/mass spectrometry (TDGC/MS). The structure of the compound has been determined and is presented in this study. Additional data obtained by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and liquid chromatography/tandem mass spectrometry (LC/MS/MS) support the proposed structure, with no reported CAS number, as 2,3-dimethyl-2,3-diisobutyl succinonitrile. It is a byproduct of the thermal decomposition of 2,2'-azobis(2,4-dimethyl valeronitrile), a commercially available free radical polymerization initiator used in polymerization processes during the manufacture of the toners. By means of head-space GC/MS, 15 toners used in black & white and colour printers have been investigated. Six of them contained 2,3-dimethyl-2,3-diisobutyl succinonitrile, which has also been detected in the respective processed paper.     

Etude d'un Couple de Diastereoisomeres en Spectrometrie de Masse: Les 2,3-Diphenyl-butanes Thréo et Erythro

The mass spectra of erythro and threo 2,3-diphenylbutanes are assigned to one rearrangement and one simple cleavage. After calculation of these spectra, it is suggested that their differences are issued essentially from the enthalpy difference of the molecular ions and not from the enthalpy difference between the rearrangement transition states. It is shown that in the gaseous state the threo 2,3-diphenylbutane is more stable than the erythro isomer.     

新引发体系引发MMA活性自由基聚合

近年来 ,关于活性自由基聚合的研究极为活跃 ,已经发现了多种基于增长链自由基被可逆钝化形成休眠种的活性自由基聚合方法[1,2 ] .它们主要包括引发转移终止剂 ( Iniferter) ,稳定自由基聚合( SFRP) ,原子转移自由基聚合 ( ATRP) ,可逆加成 -断链链转移聚合 ( RAFT)等 .其中 ATRP因其具有可聚合单体多 ,反应条件相对缓和等优点而成为该领域的研究热点 [3～ 5] .ATRP活性自由基聚合的实现主要是在过渡金属催化剂的作用下 ,通过循环往复的碳 -卤键的活化、加成、碳 -卤键的再形成而得到最终活性的聚合物 ,引发体系由引发剂、过渡金属…     

Comparative kinetic studies on the synthesis of quinoxalinone derivatives and pyrido[2,3-b]pyrazinone derivatives by the hinsberg reaction

Kinetic studies on the anelation of quinoxalinone derivatives 3a-c and pyrido[2,3-b]pyrazinone derivatives 5a-c and 6a-c synthesized by the Hinsberg reaction is reported. o-Phenylenediamine or 2,3-diaminopyridine were treated with bifunctional carbonyl compounds such as glyoxylic, pyruvic and benzoylformic acids under different experimental conditions. When pyridopyrazine derivatives were synthesized both position isomers were achieved applying regioselective reactions. Mixture were avoided by looking for special experimental conditions that led unambiguously to only one of the components of the classic “Hinsberg mixture”. Quinoxalinone derivatives 3a-c were obtained at room temperature in good yields (>90%) using anhydrous methanol or ethanol as solvents. On the other hand, only pyrido[2,3-b]pyrazin-3(4H)-one ( 5a ) was regioselectively attained in aqueous buffer of pH 7 while 3-methylpyridopyrazinone derivatives were regioselectively separated using anhydrous methanol for one isomer, 5b , and anhydrous chloroform for the other isomer, 6b , at room temperature. Yields were higher than 80%. Reactions with benzoylformic acid did not give good yields and only 2-phenylpyrido[2,3-b]pyrazin-3(4H)-one ( 5c ) could be obtained using anhydrous chloroform (yield <30%) as the solvent. Steric hindrance exerted by the phenyl group of the benzoylformic acid is supposed to be responsible of our difficulties to obtain 2-phenylpyrido[2,3-b]pyrazin-3(4H)-one ( 5c ) in good yields applying this technique. The other isomer, 3-phenyl[2,3-b]pyrazin-2(1H)-one ( 6c ) was always formed together with the former isomer and could not be isolated from the mixture, when other solvents than chloroform were used as the reaction media.