Thermodynamic Investigation of Enol↔Keto Tautomerism for Alcohol Sensors Based on Carbon Nanotubes as Chemical Sensors

Abstract Single‐walled carbon nanotubes (SWNT) are molecular‐scale wires with high mechanical stiffness and strength. The faster response and substantially higher sensitivity of chemical nanotubes sensors over existing solid‐state sensors, which was due to exposure of gaseous molecules such as C2H5OH, served as the basis to consider gas sensors based on SWNT. These factors also focused on the ethanol sensing effects of the sensors on the acetaldehyde and ethyl methyl ketone tautomerism at room temperature, which have been formed within alcohol dehydrogenation and condensation reactions involved in chain growth pathways on SWNT. Since temperature has a strong effect on structure and stability, we were interested in calculating some specific thermo chemical properties to justify the structural stability of existing isomers in keto↔enol tautomerism. So, the thermodynamic and electric properties of produced ethyl‐methyl ketone involved in keto↔enol tautomerism have been investigated using semi‐empirical methods. The obtained results showed that the keto structure is more stable because of intramolecular hydrogen bond formation due to strong C = O bond existence in the keto tautomers. Our finding implies that the semi‐empirical quantum chemical calculations can be suggested as proper methods to study the interaction of different chemical compounds with SWNT in a reliable way. Keywords: AcetaldehydeElectrical resistanceEthanol sensorEthyl methyl ketoneketo and enol tautomerismSingle‐walled carbon nanotubeThermodynamic functions