CHEM 3410 1st Edition Lecture 15Outline of CurrentI. Key Concepts ReviewII. Alcohols to EstersA. Fischer EsterificationIII. Oxidation of AlcoholsOutline of Last LectureIV. Preparation of Alcohols from carbonyls reacted with Grignard ReagentsV. Alcohol ReactionsA. Alcohols to alkyl halidesB. Alcohols to TosylatesC. Dehydration D. Manipulating stereochemistry (R,S)Current LectureI. Key Concepts ReviewWe have both acid conditions and E2 conditions for our eliminations. E1 and E2. E1 works bestfor tertiary. If I treat a tertiary alcohol with H2SO4 and a mild amount of heat (30-50 oC), I can dehydrate that tertiary alcohol into the corresponding alkene via an E1 carbocation intermediate pathway. I can also do that with secondary alcohols, but the conditions are far more severe. Concentrated sulfuric acid and a lot of heat (100+ oC). You can do this to the secondary alcohol, but you must remember that this method can destroy some compounds that may be highly sensitive to what you can doing. POCl3 can be used to dehydrate tertiary, secondary, and most primary alcohols. Not all primary alcohols will be dehydrated, you just have to work the problem to see. When doing substitution reactions on the tertiary alcohol, you can never use thionyl chloride (SOCl2) or phosphorous tribromide (PBr3) because you can never preform Sn2 substitution of atertiary substrate. You must use the acidic Sn1 conditions (HCl or HBr or KI/ H2SO4), and you would have to do the reaction with extreme excess of the acid to get more substitution ratherthan elimination products.These notes represent a detailed interpretation of the professor’s lecture. These notesare best used as a supplement to your own notes, not as a substitute.For a secondary alcohol, you can still do the substitution with HBr or HCl, but you will face two issues. The first is extreme conditions because concentrated acid and extreme heat is required (150oC). The second issue is that you may cause the compound to undergo elimination as well, leaving you with a mix of Sn1 and E1 products. Primary and secondary alcohols will always convert directly to halides if you use the two specialized reagents, thionyl chloride (SOCl2) or phosphorous tribromide (PBr3).You can NEVER dehydrate a primary alcohol with acid because the pathway for such an elimination is E1, and you would have to form a carbocation. Primary carbons will never form carbocations. You can only dehydrate SOME with POCl3 becausethe POCl3 is so stable after it leaves. It leaves some primary carbons, leaving the carbocation behind. That is why SOME primaries will work. THE ONLY WAY to turn a tertiary alcohol into a halide is to use HCl or HBr or KI/ H2SO4because you can never do SN2 chemistry on a tertiary alcohol because the tertiary center is too sterically hindered. II. Alcohols to Esters “Fischer Esterification” – works best for small alcohols. The more branched/highly substitutedthe alcohol, the worse the Fischer esterification will work.The following sequence will be on the exam:The bulky starting material makes FE difficult/ inefficient.Notice how bulky the starting material is. This is what you would expect if you tried to do FE directly:III. Oxidation of AlcoholsThere are three special oxidizers that can stop primary alcohols at aldehyde: PCC, Dess Martin Perodinance, Copper (s)You must know the structure of Dess MartinYou do not need to remember the structure of PCCThe third method only works on primary