β-elimination 

Synonym: 1,2-elimination
https://doi.org/10.1351/goldbook.08150
Transformation of the general type XABYA=B+XY (or X+Y,or XA++YA) where the central atoms A and B are commonly, but not necessarily, carbon.
Source:
PAC, 2022, 94, 353. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)) on page 376 [Terms] [Paper]