Answer in Organic Chemistry for Swagata Mondal #120164
April 21st, 2023
All cyclobutadiene derivatives possess high tendency to polymerization. Due to steric hindrance, bulky substituents (especially tert-butyl) at the cyclobutadiene ring make the molecule much more less polymerizable. Therefore, you can isolate it much easier. However, The contact with air should be avoided even for substituted cyclobutadiene.
More information you can find here: https://doi.org/10.1002/anie.197805201