探討順式-4-甲基-2,3,7-三氮二環[3.3.0]辛-2-烯類衍生物之熱解機制

Study on the thermal decomposition mechanism of cis-4-methyl-2,3,7-triazabicyclo[3.3.0]oct-2-ene derivatives

扈欣祺(Hsin-Chi Hu)

指導教授 ： 楊嘉喜

中原大學/理學院/化學系/碩士(2008年)

https://doi.org/10.6840/CYCU.2008.00077

摘要

利用熱解2,3,7-三氮-4-甲基-二環[3.3.0]辛-2-烯類化合物來澄清1-吡啶啉的熱解機制。在實驗中，熱解順式-2,3,7-三氮-4-甲基-二環[3.3.0]辛-2-烯類化合物時，反式-6-甲基-3-氮二環[3.1.0]已烷為主產物，順式-異構物與進行1,2-氫轉移而得到的3,4-二氫吡咯則為副產物。
而其中主產物的部份，是由於1號碳和2號氮之間的碳氮鍵先斷裂後，兩個氮會轉180度，隨後留在1號碳上的自由基從背後攻擊(back attack)，得到的產物。若N2未轉到180度，3號氮和4號碳之間的碳氮鍵斷裂，留下兩個保持在原來位置的兩個自由基，閉環後得到保留原來立體化學的產物(順式-同分異構物)。
當起始物加熱後，1號碳和2號氮之間的碳氮鍵斷裂後，此時若留在4號碳上的N2轉至與5號碳上的氫相反的方向，5號碳上的氫轉移至4號碳上後N2離去，就會得到二氫吡咯。若1號碳上接的取代基立體阻礙越大、拉電子效應越強，其產物中變成吡咯的比例會變多。

關鍵字

熱解機制

並列摘要

Thermolysis of trans-4-methyl-2,3,7-triazabicyclo[3.3.0]oct-2-ene derivatives was carried out in the hope of clarifying the thermal decomposition mechanism of 1-pyrazoline. In this experiment, we had found that, cis-6-methyl-3-azabicyclo[3.1.0]hexane was the major product while the trans-isomer and 3,4-dihydropyrrole, the product from 1,2-hydride shift, were the minor ones.
The reaction which produced the major product began with cleavage of C-1 and N-2 bond, followed by 180。 rotation of N2 moiety and back attack from C-1 radical to C-4. If the above event had not happened, cleavage of the carbon-nitrogen bond in N-3 between C-4 occured. The resulting diradical recombine to produce the trans-isomer.
The product of dihydropyrrol can be accounted for by the follwing mechanism. After cleavage of the C1-N2 bond, the N2 rotated to trans configuration with expect to hydrogen on the C-5. The hydrogen on the C-5 will migrate to the C-4 and, in the meantime, N2 leave to prodruce 3,4-dihydropyrrole. In the thermolysis of trans-4-methyl-2,3,7-triaza-
-bicyclo[3.3.0]oct-2-ene derivatives, It was found that if the substituent group have higher electron-withdrawing capability and steric effect, the product ratio of dihydropyrrol will be increased.

並列關鍵字

thermal decomposition mechanism

參考文獻

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