Direct transformation of n-alkane into all-trans conjugated polyene via cascade dehydrogenation.

Xuechao Li,Yen Wei,Xiaojuan Yu,Guigu Xue,Zhengming Hao,Fangsen Li,Qing Guo,Kaifeng Niu,Lifeng Chi,Haiming Zhang,Yuemin Wang,Shuai Lu,Yanning Tang,Junjie Zhang,Zhichao Xu,Pengdong Wang,Peng Liu,Chaojie Xu

doi:10.1093/nsr/nwab093

Abstract

Selective C(sp3) −H activation is of fundamental importance in processing alkane feedstocks to produce high-value-added chemical products. By virtue of an on-surface synthesis strategy, we report selective cascade dehydrogenation of n-alkane molecules under surface constraints, which yields monodispersed all-trans conjugated polyenes with unprecedented length controllability. We are also able to demonstrate the generality of this concept for alkyl-substituted molecules with programmable lengths and diverse functionalities, and more importantly its promising potential in molecular wiring.

Highlights

By virtue of an on-surface synthesis strategy, we report selective cascade dehydrogenation of n-alkane molecules under surface constraints, which yields monodispersed all-trans conjugated polyenes with unprecedented length controllability
The utilization of alkane feedstocks in synthesis is mainly restricted by the chemically inert C(sp3) −H bonds, which appeals for preliminary functionalization to enhance their chemical selectivity [1,2,3,4,5]
Upon annealing the sample at 453 K for an hour, the self-assembled lamellae are observed to disperse on the surface (Fig. 1d), presenting a similar superstructure (14.4 A ) where one of every three paraffin chains differentiates from the others in STM contrast

Summary

Introduction

The utilization of alkane feedstocks in synthesis is mainly restricted by the chemically inert C(sp3) −H bonds, which appeals for preliminary functionalization to enhance their chemical selectivity [1,2,3,4,5]. By virtue of an on-surface synthesis strategy, we report selective cascade dehydrogenation of n-alkane molecules under surface constraints, which yields monodispersed all-trans conjugated polyenes with unprecedented length controllability. The difference in molecular appearance implies a possible, but unexpected, thorough chemical transformation from saturated alkanes into the corresponding all-trans conjugated polyenes where hydrogen atoms are selectively scissored.

Results

Conclusion