The development of highly selective and practical organic transformations based on the C–H functionalization is currently an area of great research and interest, since the method can yield desired target compounds in fewer steps and with less wastes compared to the conventional pre-functionalization approaches. Professor Chang and his research group have been involved in the development of highly desirable C–H Activation methodologies, mainly since 2008. Based on the rich experiences, Chang's group will continue to develop the truly efficient and site-selective C–H activation strategies especially for C–C, C–N and C–O bond formations.
Methane (CH₄) Functionalization
Methane is abundant on Earth as a main constituent of natural gas and gas hydrate. Considering its utility, the conversion of methane into a useful chemical feedstock will be of great future use. However, there are intrinsic difficulties that hinder this transformation - extremely high C–H bond activation energy, high pka values, small polarizability. To overcome these difficulties, Chang's group will focus on the development of efficient and selective catalytic systems for controlling C–H activation of methane. Experimental and computational studies on methane activation and subsequent selective introduction of functional groups into methane will be conducted cooperatively.
Catalytic Selective Defunctionalization
An abundance of inexpensive bio-substrates can be derived from nature such as agricultural wastes, forest products, crop residues, or aquatic biomass, all of which are sustainable sources of organic carbons. While the structural portion of the bio-compounds are mainly composed of cellulose, hemicellulose, and lignin, the hydrolysis of these materials affords glucose and subsequent reduction gives bio-derived platform chemicals such as sugar alcohols. Therefore, selective defunctionalization of those substrates provides bio-based compounds such as hydrocarbons, methanol, higher molecular weight alkanes, alkenes, and methane. Although hydrogenolysis is utilized to cleave the C–C and C–O bond of bio-derived polyols (sugars and sugar alcohols), the present methods use heterogeneous catalysts under harsh conditions requiring high temperature and pressure and even non-selective. Therefore, Chang's group will concentrate on the development of selective catalytic systems allowing controlled defucntionalization of bio-derived flatform substrates under mild conditions, which will open a new avenue for the utilization of biomass-derived platform chemicals.