Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
Beilstein J Org Chem. 2013 Sep 10;9:1837-42. doi: 10.3762/bjoc.9.214. eCollection 2013.
A new approach for the investigation of a higher-order reaction by on-column reaction gas chromatography is presented. The reaction and the analytical separation are combined in a single experiment to investigate the Diels-Alder reaction of benzenediazonium-2-carboxylate as a benzyne precursor with various anthracene derivatives, i.e. anthracene, 9-bromoanthracene, 9-anthracenecarboxaldehyde and 9-anthracenemethanol. To overcome limitations of short reaction contact times at elevated temperatures a novel experimental setup was developed involving a cooling trap to achieve focusing and mixing of the reactants at a defined spot in a fused-silica capillary. This trap functions as a reactor within the separation column in the oven of a gas chromatograph. The reactants are sequentially injected to avoid undefined mixing in the injection port. An experimental protocol was developed with optimized injection intervals and cooling times to achieve sufficient conversions at short reaction times. Reaction products were rapidly identified by mass spectrometric detection. This new approach represents a practical procedure to investigate higher-order reactions at an analytical level and it simultaneously provides valuable information for the optimization of the reaction conditions.
本文提出了一种通过柱上反应气相色谱研究高阶反应的新方法。反应和分析分离在单个实验中结合，以研究苯二氮唑-2-羧酸的二烯加成反应作为苯炔前体与各种蒽衍生物，即蒽、9-溴蒽、9-蒽醛和 9-蒽甲醇。为了克服在高温下短反应接触时间的限制，开发了一种新的实验装置，涉及冷却阱，以在熔融石英毛细管中的定义点实现反应物的聚焦和混合。该阱在气相色谱仪的炉中作为分离柱内的反应器。反应物依次注入以避免在进样口处发生未定义的混合。开发了一种实验方案，优化了注入间隔和冷却时间，以在短反应时间内实现足够的转化率。通过质谱检测快速鉴定反应产物。这种新方法代表了在分析水平上研究高阶反应的实用程序，同时为优化反应条件提供了有价值的信息。
