lecture 17 sp 09 given - Lecture 17 Chemistry 310N y...

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ecture 17 Lecture 17 Chemistry 310N Organic Chemistry II for Prehealth Professionals Unique number: 53185 Tu,Th 12:30-2:00 pm, Welch 2.224 Professor: Jonathan Sessler, Ph.D. sessler@mail.utexas.edu EXAM II -- In Class March 31st, will cover through Section 19.7. hapter 19 is hard; study it and work the problems! Chapter 19 is hard; study it and work the problems! Practice Homework, posted today, should help. ustin will give a review in his recitation section Monday. Dustin will give a review in his recitation section Monday. Office hours end at 2:30 pm today (for a doctoral exam)--sorry!
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ieckman Condensation Dieckman Condensation An intramolecular Claisen condensation 1. EtO - Na + 2. H O, HCl OEt O Et O Diethyl hexanedioate (Diethyl adipate) 2 O O O + thyl 2-oxocyclo- Et OH Ethyl 2 oxocyclo pentanecarboxylate
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rossed Claisen Condensations Crossed Claisen Condensations rossed Claisen condensations between two different C ossed C a se co de sa o s be ee o d e e esters, each with α -hydrogens, give mixtures of products and are not useful. – Useful crossed Claisen condensations are possible, however, if there is an appreciable difference in reactivity between the two esters; that is, when one of them has no α -hydrogens. O O O O O HCOEt EtOCOEt COEt EtOC-COEt Diethyl ethanedioate Diethyl Eth yl Ethy l ben zoate (Diethyl oxalate) carbonate formate
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rossed Claisen Condensations Crossed Claisen Condensations – The ester with no α -hydrogens is generally used in excess. Ph OCH 3 O 3 O 1. CH 3 O - Na + 2. H 2 O, HCl 3 O O + Methyl propanoate benzoate Methyl 2-methyl-3-oxo- 3-phenylpropanoate (racemic)
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laisen Condensation Claisen Condensation laisen condensations are a route to ketones C a se co de sat o s a e a oute to eto es Reactions 1 & 2: Claisen condensation followed by acidification. OEt O 1. EtO - Na + 2. H 2 O, HCl O O Et OH + O O O O Reactions 3 & 4: Saponification and acidification 3. NaOH, H 2 O, heat 4. H 2 OH + OO O Reaction 5: Thermal decarboxylation.
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lecture 17 sp 09 given - Lecture 17 Chemistry 310N y...

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