In 1H NMR spectroscopy, the proton of a terminal alkyne (≡C-H) typically appears near 2 ppm, slightly deshielded compared to aliphatic protons but shielded relative to vinyl or aromatic protons due to the sp-hybridized carbon. A key feature of terminal alkynes is the presence of four-bond coupling (4J), which is often observable. For example, in 1-butyne, the terminal alkyne proton is split into a triplet due to coupling with the two equivalent methylene (CH₂) protons four bonds away. Likewise the CH₂ unit is spit into a doublet of quartets. This splitting pattern is a distinctive characteristic of terminal alkynes and can be observed by expanding the signal near 2 ppm. In 13C NMR spectroscopy, the sp-hybridized carbons of alkynes resonate in distinct regions: the terminal alkyne carbon (≡C-H) typically appears around 65–85 ppm, while the internal alkyne carbon (≡C-R) is more deshielded and appears in the range of 70–100 ppm. These chemical shifts, along with coupling patterns in 1H NMR, provide valuable information for identifying alkyne structures.