On the Study of 4-Fluorocinnamic Acid by Nuclear Magnetic Resonance (NMR).

4-fluorocinnamic acid has a unique molecular structure. It contains fluorine atoms, is connected by benzene rings, and has the basic skeleton of cinnamic acid. This structural property makes it unique in various chemical reactions and material synthesis.

Nuclear magnetic resonance is a powerful tool for analyzing molecular structure. Based on the NMR study of 4-fluorocinnamic acid, on the hydrogen spectrum, phenylcyclohydrogen, alkenyl hydrogen and carboxyl ortho-hydrogen show peaks at specific chemical shifts. The peak of phenylcyclohydrogen shifts slightly to the lower field due to the electronegativity of the fluorine atom. The peak of alkenyl hydrogen, according to its cis-trans isomerism, has different peak shapes and coupling constants, which can be used as evidence for conformational determination. The peak of carboxyl ortho-hydrogen also has corresponding chemical shifts due to the electron-absorbing effect of the carboxyl group. In the

carbon spectrum, each carbon of 4-fluorocinnamic acid shows peaks at specific chemical shifts according to its chemical environment. Phenylcyclocarbon, alkenyl carbon and carboxyl carbon have their own chemical shifts. The influence of fluorine atoms on ortho-carbon can also be observed in the chemical shift of carbon spectrum.

The NMR study of 4-fluorocinnamic acid can not only reveal the fine structure of its molecule, but also identify the reaction process and determine the purity of the product in the process of organic synthesis. In the fields of materials science, it can also provide important information for the study of the relationship between its properties and structure. Therefore, the NMR study of 4-fluorocinnamic acid is of great significance in many branches of chemistry.