Single step process transforms carbon dioxide into star-shaped molecules
Carbon dioxide is a useful feedstock gas for synthesis of complex, functional materials. The power of carbon dioxide has been harnessed by Singapore’s Agency for Science, Technology and Research researchers to make two symmetrical star-shaped molecules in a single step. These molecules could be used to build complex, functional polymeric materials useful for catalysis, coatings and drug delivery. Carbon dioxide is a cheap and accessible base material, explains lead researcher He-Kuan Luo from the Institute of Materials Research and Engineering. “Therefore, many people are searching for efficient methods to transform carbon dioxide into useful molecules,” he explains. “But transforming carbon dioxide is not typically easy.” His team has developed a simple route to use carbon dioxide to make aromatic compounds that can be used as building blocks for more complicated materials. They created symmetrical benzene rings with three or six identical arms comprising carbonate groups terminated by carbon–carbon triple bonds, or ‘alkynes’. “We can integrate the carbon dioxide into the molecule without the need for high temperatures or high pressure,” says Luo. The molecules were made in a single step. The team introduced carbon dioxide from dry ice to an alcohol with an alkyne end group and benzene rings decorated with either three or six alkyl bromide groups. “At the beginning, however, only some of the branches reacted so we could not get the desired compound,” Luo explains. The team fine-tuned the process and found the reactions worked most efficiently at room temperature, with the carbon dioxide at atmospheric pressure and with the addition of both a promoter tetrabutylammonium bromide (TBAB) and the base potassium carbonate. “We tried many times and after a few months, we finally got [the bromide groups in] all six branches to react [with the alcohol],” he says. Adding the promoter to the mix doubled the […]