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Cyclobutadiene is not stable at room temperature. Upon
Chapter 18, Problem 18.71(choose chapter or problem)
Cyclobutadiene is not stable at room temperature. Upon formation, it rapidly dimerizes via a Diels- Alder reaction. However, several derivatives of cyclobutadiene are known to be stable at room temperature (Angew Chem. Int. Ed. 1988, 27, 14371455): R1 R2 R4 R3 (a) One such derivative is tri- tert-butylcyclobutadiene (R1=R2=R3= t-Bu; R4=H). Suggest an explanation for why this compound is stable. (b) Another stable derivative of cyclobutadiene has been prepared in which R1=R3=NEt2 and R2=R4=CO2Et. Suggest an explanation for why this compound is stable. (c) In part (b), we saw that cyclobutadiene is stabilized by the presence of neighboring NEt2 and CO2Et groups. In contrast, the presence of these two groups has a destabilizing effect on systems with 4n+2 p electrons. Explain this observation.
Questions & Answers
QUESTION:
Cyclobutadiene is not stable at room temperature. Upon formation, it rapidly dimerizes via a Diels- Alder reaction. However, several derivatives of cyclobutadiene are known to be stable at room temperature (Angew Chem. Int. Ed. 1988, 27, 14371455): R1 R2 R4 R3 (a) One such derivative is tri- tert-butylcyclobutadiene (R1=R2=R3= t-Bu; R4=H). Suggest an explanation for why this compound is stable. (b) Another stable derivative of cyclobutadiene has been prepared in which R1=R3=NEt2 and R2=R4=CO2Et. Suggest an explanation for why this compound is stable. (c) In part (b), we saw that cyclobutadiene is stabilized by the presence of neighboring NEt2 and CO2Et groups. In contrast, the presence of these two groups has a destabilizing effect on systems with 4n+2 p electrons. Explain this observation.
ANSWER:Step 1 of 4
(a)
From the given, One of the derivative of cyclobutane is tri- tert - butyl cyclobutadiene where 
