CH 220 1st Edition Lecture 9 Outline of Current Lecture I. Electrophilic Addition of AlkenesII. Carbocation structure and stabilityIII. Diverse reactions of AlkenesIV. Hydration of AlkenesV. Addition of Halogens to AlkenesCurrent Lecture I. Electrophilic Addition of AlkenesMarkovnikov’s rule observed that if you add HX (being a hydrohalic acid) to an alkene, the H attaches to the carbon with the most Hs and X (the halogen) attached to the other end. This helps you to predict the outcome without drawing out the reaction mechanism.This rule, however, is only useful for reactions that go through a carbocation reaction + HBrOn the structure of 2-pentene, above, it is evident that carbon 2 & 3 have the same amount of hydrogens, so we have to add the Bromine onto the 2nd and 3rd Carbon in two separate reactions, resulting in 2 different products being formed, 2-bromopentane and 3-bromopentane.When performing this reaction, you are equally likely to get either of the above products. Regiospecific reactions are unlike the previous reaction in that you can predict the product, which means that it would be a good reaction (monetarily speaking) because you would always get 100% productThese 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.Lecture 9 When the reaction is not regiospecific, separations are required, which take time and money and make chemicals expensive. II. Carbocation structure and stabilityIII. Diverse reactions of AlkenesAlkenes react with many electrophiles to give useful products by addition (often through specialreagents)Alcohols are important in organic chemistry because they make organic compounds soluble in waterIV. Hydration of Alkenes (Addition of H2O)The addition of H2O to give an alcoholAcid catalysts are used in high temperaturesFollows Markovnikov’s RuleNeeds a catalyst such as H3PO4 (Phosphoric Acid) or H2SO4 (Sulfuric Acid)A hydration reaction is different that hydrohalogenation because it needs an acid because H2O isn’t as good of a reagent as an acid halide. It also needs to be heated to 250C, which means thewater is vapor and this is a vapor reaction.If you see H+/H20, it means it is a hydration reactionIf you see ‘Aqueous Acid’ in a question, it is going to be a hydration reactionV. Addition of Halogens to AlkenesWorks with Bromine (Br2) and Chlorine (Cl2)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. CH 220 1st EditionLecture 9 F2 is too reactive and I2 is not reactive enoughCl2 reacts as Cl+/Cl-Br2 is similar The reaction doesn’t go through a carbon cationThe reaction doesn’t follow Markovnikov’s ruleAddition is exclusively transOne of the bromines gets attacked by the double bond, resulting in the bromine being bonded to two carbons and gains a positive charge. This is known as a bromonium ion (middle diagram)The shared electron pair (left diagram) gets given to the remaining bromine, this bromine has toattack the carbon from the bottom (middle diagram). This results in a trans structure.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. CH 220 1st