CHEM 261 1st Edition Lecture 18Outline of Last Lecture:I. Revisiting Alkene StabilityII. Substitution of CycloalkenesIII. Electrophile AdditionOutline of Current Lecture:I. Markovnikov’s Rule/Hammond Postulate ReviewII. Addition with Substituted Cyclohexenes (Chiral/achiral)III. Carbocation RearrangementsMarkovnikov’s Rule/Hammond Postulate Review:1o<2o<3o<4o (most stable is the quaternary carbocation)-According to Markovnikov’s rule, in an HX addition to an alkene, the H+ adds to the least substituted end of the C=C (the least stable carbocation). The “X” goes to the other, more substituted carbon, producing a Markovnikov product. An anti-Markovnikov product is the opposite outcome, in which the H+ goes to the more substituted carbon and the “X” goes to theless substituted carbon. This product is hypothetical and will never exist. Hammond Postulate:-The higher energy product is LESS stable, and the lower energy product is MORE stable. The more stable products will form faster in the case where there are TWO DIFFERENT products-When the products are the same, the less stable reactant is faster. -The transition state is structurally most similar to the reaction side that is it closer to in energy. Addition with Substituted Cyclohexenes (chiral/achiral):-With achiral cyclohexenes, the most substituted carbon gets the “X” from HX, creating the Markovnikov product. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-With chiral, it depends on which side the “X” comes from (top or bottom). Could produce a cis or a trans product. Carbocation Rearrangements: **on adjacent carbons, is there a more stable C+ possible?-“hydride shift”, the H on the R group “shifts” to the adjacent carbon, creating a new C+-Don’t know if it will happen, but have to account for the possibility-Carbocations tend to shift the bond next to the
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