chapter 5 reactions of alkenes and alkynes 1 dr. sujatha krishnaswamy chemistry faculty chandler...
TRANSCRIPT
Chapter 5
Reactions of Alkenes and Alkynes
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Dr. Sujatha KrishnaswamyChemistry Faculty
Chandler Gilbert Community College
Chapter 4 Problem 18
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Chapter 4 Problem 17
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The characteristic reaction of alkenes is addition—the bond is broken and two new bonds are formed.
Because alkenes are electron rich, simple alkenes do not react
with nucleophiles or bases, reagents that are themselves
electron rich. Alkenes react with electrophiles.
Addition Reactions
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Hydrohalogenation - Addition of HX
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Chapter 4 Problem 14
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To draw the products of an addition reaction:
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Addition of HX is regioselective
Markovnikov’s rule: in additions of HX, H adds to the carbon
with the greater number of hydrogens9
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Stability of Carbocations
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Chapter 5 Problem 3
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Predict the major product in each reaction.
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More reactions…..
Chapter 5 Page 112 Problem 4
Page 116 Problem 10
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Synthesis
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Addition of H2O, Hydration
acid-catalyzed hydration of an alkene is regioselective; hydrogen adds preferentially to the sp2 carbon with less # of hydrogens.
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What products are obtained upon hydration of the following alkenes?
Synthesis - How can you make these alcohols?
Addition of Cl2 and Br2
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addition is stereoselective stereoselective reaction: a reaction in which one
stereoisomer is formed or destroyed in preference to all others that might be formed or destroyed
addition to a cycloalkene, for example, gives only a trans product
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Reduction of AlkenesAlkenes react with H2 in the presence of a transition metal
catalyst to give alkanesthe most commonly used catalysts are Pd, Pt, and Ni
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Predict the products of hydrogenation (reduction) of
Alkynes
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Addition of HX to Alkynes
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Addition of Halogens to Alkynes
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Hydration of Internal Vs Terminal Alkynes
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Keto-enol tautomers
Addition of Hydrogen to Alkynes
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Alkane formation:
Reduction of an Alkyne to an Alkane
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Addition of Hydrogen to Alkynes - Formation of cis Alkene
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Conversion of Internal Alkynes to trans Alkenes
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Summary of Alkyne Reductions
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