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Preparation and Isolation of Purely Stereoregular Oligomers without Molecular Weight Distribution and Structural Investigations of the Oligomers

无分子量分布的纯立构低聚物的制备和分离以及低聚物的结构研究

基本信息

批准号：
03453118
负责人：
HATADA Koichi
金额：
$ 4.93万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

项目摘要

Highly isotactic(it-) and highly syndiotactic(st-) oligomers of methy1 methacrylate (MMA) were prepared by the stereospecific living polymerizations of MMA.The oligomers were separated into the individual homologues from the 10mer to the 100mer (C_<504>H_<810>O_<200> = 10,070) by means of preparative supercritical fluid chromatography (SFC). The molecular weight dependence of the glass transition temperature for the it- and st- oligomer series was investigated using the samples of the 19 - 50mers. The it-oligomers with the degree of polymerization higher than 30 crystallized by annealing, and the melting endotherms of the uniform oligomers were sharper than that of the oligomer having molecular weight distribution. The it-5mer and st-4mer gave single crystals, and the crystal structures were determined by X-ray analysis. When the it-50mer and st-50mer were mixed and subjected to the GPC using THF as eluent, a sharp elution peak due to the stereocomplex between the 50mers was observed at the elution volume corresponding to the 100mer ; on the basis of the GPC analysis of the oligomer mixtures, the complexation stoichiometry and the mechanism of the complexation were studied.Purely it-oligomers of chloral (CCl_3CHO) with a structure RO[CH(CCl_3)O]_nR' were prepared by the oligomerization of chloral initiated with RONa and terminated with R'X.The oligomers from the 2mer to the 9mer were isolated individually as single crystals by GPC or SFC.Each it-oligomer having t-butyl and acetyl groups as R and R', respectively, could be resolved into the optical antipodes by HPLC.The (-)-5mer([alpa]_D = -23.7 ) was found to be the (R,R,R,R,R)-isomer having a right-handed 4/1 helical structure by X-ray analysis. The it-7mer and it-8mer carrying a methyl group at both ends, which are the meso isomers, could also be optically resolved based entirely on conformational chirality (one-handed helix).

通过甲基丙烯酸甲酯（MMA）的立体定向活性聚合制备了高度全同立构（it-）和高度间同立构（st-）的MMA低聚物，用制备超临界流体色谱（SFC）将其分离为10 ~ 100聚体（C_<504>H_<810>O_<200>= 10，070）的单体。用19 - 50聚体的样品研究了it-和st-齐聚物系列的玻璃化转变温度与分子量的关系。聚合度大于30的低聚物通过退火结晶，并且均匀的低聚物的熔融吸热比具有分子量分布的低聚物的熔融吸热更尖锐。it-5 mer和st-4 mer均为单晶，晶体结构经X射线衍射分析确定。当将it-50聚体和st-50聚体混合并使用THF作为洗脱剂进行GPC时，在对应于100聚体的洗脱体积处观察到由于50聚体之间的立体复合物而引起的尖锐洗脱峰;基于低聚物混合物的GPC分析，研究了络合物的化学计量比和络合机理，以三氯乙醛为原料，RONa为引发剂，R 'X为封端剂，通过氯醛的齐聚反应，合成了结构为RO[CH（CCl_3）O]_nR'的CCl_3CHO。（-）-5聚体（[α]_D = -23.7）经X射线衍射分析为右旋4/1螺旋结构的（R，R，R，R，R）-异构体。在两个末端携带甲基的it-7聚体和it-8聚体（它们是内消旋异构体）也可以完全基于构象手性（单手螺旋）进行光学拆分。