Notes2_AdditiontoPiLecture

Notes2_AdditiontoPiLecture - Cis/Trans, E and Z? H C R C H...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Cis/Trans, E and Z? H C R C H R R C H C R H C C Cl Trans Cis H H3C Trans H H Cl C H3C C CH2CH3 H C H3C C H CH2CH3 The Alkyl groups are cis The proper IUPAC name is with E/Z nomenclature E Cis Copyright 2008 Stephanie L. Gould H C C Cl High Br High E Copyright 2008 Stephanie L. Gould Addition to Carbon-Carbon Pi Bonds Lecture Supplements: pg. 2124 CFC, OWLS, PP: pg. 144168 Vollhardt: Chapter 12, SecQons 121 to 128, 1212 Chapter 13, SecQon 137 Klein: Chapter 11 (OpQonal) All materials herein are copyright 2008 Stephanie L. Gould. Materials are intended for personal use in conjuncQon with Chemistry 14D at UCLA. DistribuQon is not permi\ed. Alkenes and Alkynes See Vollhart pg. 37 Alkene, one sigma bond, one pi bond Alkyne, one sigma bond, two pi bond This topic will deal with addiQon to the pi bonds Copyright 2008 Stephanie L. Gould Figure from Vollhardt pg. 37 Alkenes in Everyday Life Monomers of common plasQcs H C H C H H H H C C H H CH3 H C C H Cl Ethylene (polyethylene) Propylene (polypropylene) Vinyl Chloride (polyvinyl chloride, PVC) Industrial Cleaners Cl C Cl C Cl Cl Natural AnQoxidants (Lycopene) tetrachloro ethylene "perc" Copyright 2008 Stephanie L. Gould Generalized Addition to Pi Bonds Rxn R C R C R R E electrophile R R R R nucleophile R R R E N R Components Alkene, Electrophile, Nucleophile ConsideraQons 1) Electrophile AddiQon site 2) Nucleophile AddiQon OrientaQon with respect to Electrophile Copyright 2008 Stephanie L. Gould Addition to C=C 1) AddiQon of HX to C=C and CC ** 2) AddiQon of Halogens (X2) to C=C and CC ** 3) Alcohol FormaQon from Alkenes 1) Acid Catalysis ** 2) OxymercuraQon/DemercuraQon 3) HydroboraQon/OxidaQon 4) HydrogenaQon 5) Ozonolysis ** You should know these mechanisms. Knowing the mechanisms of the other reacQon will help you understand the major product. Knowing the major product is required, the Copyright 2008 Stephanie L. Gould mechanisms for nonstared rxns are not required. Addition of HX to C=CX = Cl, Br, I R C R C R R E electrophile R R R R nucleophile R R R E N R + H X Copyright 2008 Stephanie L. Gould Energy Diagram [TS1] [TS2] Ea1 CarbocaQon Reactant/ Reagent Ea2 AddiQon Product Reaction Coordinate Copyright 2008 Stephanie L. Gould Regioselective Nature of Addition Major Intermediate H C C H H Br C C H H H Minor Intermediate H + C H C H + Br Br- H C Br C H H Copyright 2008 Stephanie L. Gould Markovnikov's Rule Discovered by Vladimir Vasilyevich Markovnikov in 1850: When a hydrogen halide adds to an alkene the hydrogen adds to the carbon bearing the most hydrogen subsQtuents (least subsQtuted) and the halide adds to the carbon with the least number of hydrogen atoms (most subsQtuted) Copyright 2008 Stephanie L. Gould Picture from Wikipedia.com Rearrangements C+ intermediate! IH H H I H H H H + IH H H H H I H H H H Copyright 2008 Stephanie L. Gould H-X addition to -CCH H Br H CH3 H Br + H CH3 BrH CH3 H Br H H H Br Br CH3 H H Br + H CH3 Br- Copyright 2008 Stephanie L. Gould Provide the major Product CH3 CH3 HCl CCl4 Cl H HBr CH2 CH3 Br (CH3)3OK (CH3)3OH CH2 NaOH CH3OH Copyright 2008 Stephanie L. Gould End of Lecture 1 Start of Lecture 2 Administrative Exam 1 Wednesday Broad 2160E (Auditorium) Bring your pens/pencil and model kits Blue or Black pen preferred Absolutely no electronics of any sort You may not use your cell phone as a clock Bring your ID! Regrades only based on policy regarding regrades AND if only pen is used (no eraser, white out or pencils) are used on the exam Copyright 2008 Stephanie L. Gould Provide the major Product H H H HI H I- H H + H H CH3CH2OH H I H3CH2CO CH3CH2ODMSO H Copyright 2008 Stephanie L. Gould Addition to C=C 1) AddiQon of HX to C=C and CC ** 2) AddiQon of Halogens (X2) to C=C and CC ** 3) Alcohol FormaQon from Alkenes 1) Acid Catalysis ** 2) OxymercuraQon/DemercuraQon 3) HydroboraQon/OxidaQon 4) HydrogenaQon 5) Ozonolysis ** You should know these mechanisms. Knowing the mechanisms of the other reacQon will help you understand the major product. Knowing the major product is required, the Copyright 2008 Stephanie L. Gould mechanisms for nonstared rxns are not required. Addition of X2 to C=CX2 C C X C C X AnQ AddiQon + X When X = Cl or Br X Copyright 2008 Stephanie L. Gould Mechanism See Vollhart pg. 512 for Figures Copyright 2008 Stephanie L. Gould Figures from Vollhardt pg. 512 Practice Draw the Mechanism Br Br Br Br + BrBr Br Br If stereocenters are in product will have a racemate (mixture of stereoisomers) Copyright 2008 Stephanie L. Gould Provide the major Product CH3 CH3 Br2 CH2Cl2 Br + CH3 Br Br Br Copyright 2008 Stephanie L. Gould Provide the Mechanism CH3 CH3 Br2 CH2Cl2 Br + CH3 Br Br Br Br CH3 Br CH3 Br Br + Br- CH3 + Br CH3 Br Br + CH3 Br CH3 Br + CH3 Br + Br- Br Br Copyright 2008 Stephanie L. Gould Halohydrin Formation See Vollhart pg. 513 Copyright 2008 Stephanie L. Gould Figure from Vollhardt pg. 513 Provide the Mechanism CH3 Br2 H2O Br OH CH3 + CH3 OH Br CH3 Br CH3 Br Br CH3 Br OH2 + H2O CH3 Br -H+ OH CH3 Br CH2 + H2O OH Br -H+ CH3 OH Br Copyright 2008 Stephanie L. Gould End of Lecture 2 Start of Lecture 3 Administrative Exam 1 TODAY! Broad 2160E (Auditorium) 57pm If you are late no extra Qme will be given Bring your UCLA ID Copyright 2008 Stephanie L. Gould Abreviations Methyl CH3 Me Ethyl CH3CH2 Et Propyl CH3CH2CH2 Pr (isopropyl iPr) Butyl CH3CH2CH2CH2 Bu (CH3)3C tBu or tBu TertButyl Copyright 2008 Stephanie L. Gould Draw the Mechanism Conc. H2SO4 HO H H O H O H H H+ Copyright 2008 Stephanie L. Gould Additions to C=C 1) AddiQon of HX to C=C and CC ** 2) AddiQon of Halogens (X2) to C=C and CC ** 3) Alcohol FormaQon from Alkenes 1) Acid Catalysis ** 2) OxymercuraQon/DemercuraQon 3) HydroboraQon/OxidaQon 4) HydrogenaQon 5) Ozonolysis ** You should know these mechanisms. Knowing the mechanisms of the other reacQon will help you understand the major product. Knowing the major product is required, the Copyright 2008 Stephanie L. Gould mechanisms for nonstared rxns are not required. Formation of Alcohols (Addition of H2O) R C R C R R H H2O R R R OH R 1) **Acid Catalysis Markovnikov AddiQon, Not stereospecific, Rearrangement 2) OxymercuraQon/DemercuraQon Markovnikov AddiQon No Rearrangement, Not stereospecific 3) HydroboraQon/OxidaQon AnQMarkovnikov Stereospecific SynAddiQon No Rearrangement Copyright 2008 Stephanie L. Gould Acid Catalyzed Hydration H H3C C H3C C H H H+ H3C C H3C C H H H O H H H O H H H O H H HO H3C H3C H H H H3C H3C Markovnikov's AddiQon Forms most stable C+ Not Stereospecific (a\ack into either lobe of C+ orbitals C+ can rearrange H3C O H H + H3C C C H Strong Acid Copyright 2008 Stephanie L. Gould H Weak/Low ConcentraQon Acid HO H3C H3C H H H Oxymercuration/Demercuration Step 1: OxymercuraQon Hg(OAc)2, H2O OH Hg(OAc) Step 2: DemercuraQon OH Hg(OAc) Copyright 2008 Stephanie L. Gould NaBH4, NaOH H2O H OH Oxymercuration/Demercuration 1. Hg(OAc)2, H2O 2. NaBH4, NaOH H2O H OH Markovnikov's AddiQon Forms Hg+ species Not Stereospecific Avoids C+ therefore no rearrangement 1. Hg(OAc)2, ROH 2. NaBH4, NaOH H2O Copyright 2008 Stephanie L. Gould H OR Hydroboration/Oxidation Step 1: HydroboraQon H + B H H H BH2 2 B(R)3 H.C. Brown Nobel Prize 1979 Step 2: OxidaQon H BR2 H2O2, NaOH H2O H 3 OH + Na3B(OH)3 Copyright 2008 Stephanie L. Gould h\p://nobelprize.org/nobel_prizes/chemistry/laureates/1979/brownautobio.html Hydroboration/Oxidation 1. BH3, THF 2. H2O2, NaOH H2O H H H OH OH Adds to Least SubsQtuted Carbon (AnQMarkovnikov) Stereospecific Syn AddiQon No rearrangement Copyright 2008 Stephanie L. Gould Provide the major Product 1. Hg(OAc)2, H2O 2. NaBH4, NaOH H2O 1. BH3, THF 2. H2O2, NaOH H2O cat. H2SO4 OH OH H HO 1. Hg(OAc)2, CH3OH 2. NaBH4, NaOH H2O Copyright 2008 Stephanie L. Gould OCH3 Draw the Mechanism H+ cat. H2SO4 HO H H H O H H H O H O H H Copyright 2008 Stephanie L. Gould End of Lecture 3 Start of Lecture 4 Addition to C=C 1) AddiQon of HX to C=C and CC ** 2) AddiQon of Halogens (X2) to C=C and CC ** 3) Alcohol FormaQon from Alkenes 1) Acid Catalysis ** 2) OxymercuraQon/DemercuraQon 3) HydroboraQon/OxidaQon 4) HydrogenaQon 5) Ozonolysis ** You should know these mechanisms. Knowing the mechanisms of the other reacQon will help you understand the major product. Knowing the major product is required, the Copyright 2008 Stephanie L. Gould mechanisms for nonstared rxns are not required. Hydrogenation R C R C R R H2 Catalyst R R R H H R Syn AddiQon HydrogenaQon is Stereospecific Common Catalysts: Pd/C PtO2 Raney Nickel (RaNi) Copyright 2008 Stephanie L. Gould See Vollhart pg. 37 Copyright 2008 Stephanie L. Gould Figure from Vollhardt pg. 503 Provide the Major Product H C H C H H2 Pd/C H H H H H H C H C H2 PtO2 H H + H H H H H H CH2CH3 H H2 PtO2 CH2CH3 CH2CH3 H + H H CH3 CH3 CH3 Racemic mixture Equal amounts of each enantiomer Copyright 2008 Stephanie L. Gould Additions to C=C 1) AddiQon of HX to C=C and CC ** 2) AddiQon of Halogens (X2) to C=C and CC ** 3) Alcohol FormaQon from Alkenes 1) Acid Catalysis ** 2) OxymercuraQon/DemercuraQon 3) HydroboraQon/OxidaQon 4) HydrogenaQon 5) Ozonolysis ** You should know these mechanisms. Knowing the mechanisms of the other reacQon will help you understand the major product. Knowing the major product is required, the Copyright 2008 Stephanie L. Gould mechanisms for nonstared rxns are not required. Ozonolysis OxidaQve Cleavage of C=C R C R C R R 1. O3, CH2Cl2 2. Zn, AcOH R R C O + O C R R 1. O3, CH2Cl2 C C H 2. Zn, AcOH C O + O C H Copyright 2008 Stephanie L. Gould Worksheet Problems a) 1. Br2 / CCl4 2. NaNH2 (xs) H3O+ b) H2O HO c) 1. Hg(OAc)2 / THF / CH3OH 2. NaBH4 Copyright 2008 Stephanie L. Gould OCH3 Worksheet Problems Br Br Br + d) Br2 CCl4 Br O e) 1. O3 / DMS 2. Zn / HOAc O H f) H2O Cat. H2SO4 OH Copyright 2008 Stephanie L. Gould ...
View Full Document

This note was uploaded on 08/20/2008 for the course CHEM 14D taught by Professor Hardinger during the Spring '08 term at UCLA.

Ask a homework question - tutors are online