Consider the molecule 1-bromo-1-chloro-2-fluoro-2-iodoethene in its strictly E-configuration. What i — Isomerism and Stereochemistry Chemistry Question
Question
Consider the molecule 1-bromo-1-chloro-2-fluoro-2-iodoethene in its strictly E-configuration. What is the calculated sum of the atomic numbers of the two highest-priority substituent groups (one on each $sp^2$ hybridized carbon) as determined by the standard Cahn-Ingold-Prelog (CIP) sequence rules?
💡 Solution & Explanation
The two $sp^2$ carbons are bonded to (Cl, Br) and (F, I). According to CIP Rule 1, priority is assigned based on atomic number. For C1, Bromine ($Z=35$) > Chlorine ($Z=17$). For C2, Iodine ($Z=53$) > Fluorine ($Z=9$). The highest priority groups are Br and I. The sum of their atomic numbers is $35 + 53 = 88$. Wait, let me re-evaluate based on the prompt text: The prompt text asked for Cl vs F and I vs Br. If the molecule is 1-bromo-1-chloro-2-fluoro-2-iodoethene, C1 has Br(35) and Cl(17) -> Br wins. C2 has I(53) and F(9) -> I wins. Sum = 35 + 53 = 88.