Description acceptable. Brassard’s and Rawal’s dienes favor atoms with high values of this property in variants of the Diels–Alder reaction. Reactions that favor high values of this property are driven by higher values of the heat of hydrogenation. A rule favoring higher values of this property is subverted via exhaustive methylation of a nitrogen atom during one elimination. Carbocations settle on atoms with a local maximum of this property to terminate repeated alkyl or hydride shifts. Stabilization of carbocations by hyperconjugation allow SN1 reactions to dominate SN2 at atoms with high values for this property. This property directs the regio·selectivity of Zaitsev’s rule for alkene-forming eliminations and Markovnikov’s rule for additions. For 10 points, describe this property that differentiates primary, secondary, tertiary, and quaternary atoms. ■END■
ANSWER: degree of substitution [accept answers describing how many R groups, substituents, other groups, or other (non-hydrogen) atoms an atom is bonded to; accept answers describing whether an atom is primary or secondary or tertiary or quaternary until read; prompt on answers involving steric effects or steric bulk]
<Chemistry>
= Average correct buzz position