wk2_lecture - 9/12/2008 Where is the syllabus for this...

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Unformatted text preview: 9/12/2008 Where is the syllabus for this course? http://www.ic.sunysb.edu/Class/che321ff/ Choose the true statements about the following constitutional isomers. 1. These compounds are predicted to have exactly the same bioligical activity. 2. These compounds are predicted to have exactly the same stability. O H2N O H H2N O O H H O O NH2 OK, but what material will the lecture cover next Monday? The plan is to finish Chapter 12 on December 12 This schedule will cover about 13 pages of text/day. C4H9NO2 C4H9NO2 C4H9NO2 A. Only 1 is true. B. Only 2 is true. C. Both 1 and 2 are true. 1 Remember: WORK PROBLEMS C. Neither 1 or 2 is true. 2 energy energy O H2N O H H2N O O H H O O NH2 H2N O O H H2N O O H H O O NH2 C4H9NO2 C4H9NO2 C4H9NO2 C4H9NO2 C4H9NO2 What is the relationship of these molecules to each other? 3 What is the relationship of these molecules to each other? 4 energy energy O H2N O H H2N O O H H O O NH2 H2N O O H H O O NH2 C4H9NO2 C4H9NO2 C4H9NO2 C4H9NO2 What is the relationship of these molecules to each other? 5 What is the "glue" that holds the atoms together to form all of the different molecules of organic chemistry? 6 1 9/12/2008 What are the forces holding the carbon atoms together in gamma aminobutyric acid? electrostatics attraction + nuclei C C electrons + repulsion + hydrogen atom H nuclei - repulsion electrons - O H2N C C O H hydrogen atom H A. Electrostatic forces. B. Gravitational forces. C. Nuclear forces. D. Astronomical forces. E. Supernatural forces. 7 8 electrostatics attraction What is the "glue" that holds the hydrogen atoms together to form H2? + repulsion + hydrogen atom H H H nuclei - repulsion electrons - hydrogen atom H + H H n1 e1 H H + H H e2 n2 energy energy H--H 9 H--H 10 Why is HH more stable than two hydrogen atoms (H)? HH A. The attraction of e1 to e2. B. The attraction of n1 to n2. C. The attraction of n1 to e1 and the attraction of n2 to e2. D. The attraction of n1 to e2 and the attraction of n2 to e!. electrostatics + repulsion + hydrogen atom H n2 nuclei - repulsion electrons - hydrogen atom H attraction n1 e1 H H + H H e2 energy energy H--H 11 strong attraction 12 2 9/12/2008 The classical electrostatic model for bonding was very successful but it had some difficulties. A new theory for chemical bonding was necessary. 1. the circulating electrons did not emit light. 2. the electron did not collapse into the nucleus. What was this new theory of chemical bonding? A. Gravitational theory. B. Quantum theory. C. Nuclear theory. D. String theory. H H H H energy H H 13 energy H H 14 What was a major understanding that allowed the development of Quantum theory? A. electrons have no mass. B. protons have no mass. C. electrons have wave properties. D. neutrons can be ignored. an electron = a particle a wave When it was postulated that electrons have wave properties the difficulties of the classic electrostatic model disappeared q and quantum or wave mechanics was developed. H H H H energy H H 15 energy H H 16 How has quantum mechanics increased our understanding of molecules; their structures and how they react? How has quantum mechanics increased our understanding of molecules; their structures and how they react? quantum mechanics quantum mechanics x y atomic 2s orbital + higher energy d and f atomic orbitals 3 atomic 2p orbitals H atomic 1s orbital H Z 17 18 3 9/12/2008 Atomic s, p orbitals and their hybrids. How are the orbitals arranged about a sp hybridized atom? x y Z 1 s orbital 3 p orbitals 19 2 sp hybrid orbitals pz + py atomic orbitals 20 How are the orbitals arranged about a sp hybridized atom? How are the orbitals arranged about a sp hybridized atom? sp hybridized atom 2 sp hybrid orbitals pz + py atomic orbitals 21 2 sp hybrid orbitals pz + py atomic orbitals 22 Does an sp orbital have any p orbital character? s + px sp sp Consider the combination of one s atomic orbital and two p atomic orbitals. s px py y z x + + pz 23 24 4 9/12/2008 How many sp2 hybrid orbitals will result from the combination of one s atomic orbital and two p atomic orbitals? A. 1 B. 2 C. 3 How many sp2 hybrid orbitals will result from the combination of one s atomic orbital and two p atomic orbitals? A. 1 B. 2 C. 3 x y z y z x How will these 3 sp2 hybrid orbitals be arranged in space? pz 25 pz A. xy plane B. xz plane C. yz plane 26 How are the hybrid orbitals arranged about a sp2 hybridized atom? How many hybrid orbitals are on an sp3 hybridized atom? s px py z y z x y interorbital angle = 120 120 x an sp2 hybridized atom pz 27 pz 28 How many hybrid orbitals are on an sp3 hybridized atom? Summary sp sp2 sp3 interorbital angle = 109.5 109.5 x y z hybrid orbitals generally used for -bonds an sp3 hybridized atom atomic orbitals 29 generally used for -bonds 30 5 9/12/2008 Summary sp 180 Why are hybrid orbitals used in the bonding of atoms to each other to form molecules? sp2 120 sp3 1. Hybrid orbitals can accommodate the diverse shapes observed for molecules. (VSEPR) hybrid orbitals linear trigonal planar tetrahedral hybrid orbitals linear trigonal planar tetrahedral atomic orbitals generally used for -bonds atomic orbitals generally used for -bonds Why are hybrid orbitals used in the bonding of atoms to each other to form molecules? 1. Hybrid orbitals can accommodate the diverse shapes observed for molecules. (VSEPR) Why are hybrid orbitals used in the bonding of atoms to each other to form molecules? 1. Hybrid orbitals can accommodate the diverse shapes observed for molecules. (VSEPR) hybrid orbital hybrid orbital atomic orbital atomic orbital 2. Hybrid orbitals can form stronger bonds. Which hybridization would you anticipate the carbon atom to use in methane? Hs-Csp3 HH H H H What orbitals are used to form this bond? HH hybrid orbitals (A) sp (B) sp 2 H A. Csp Csp (C) sp 3 B. B Csp Csp2 C. Csp2 Csp2 D. Csp2 Csp3 E. Csp3 Csp3 F. Cp - Cp 35 36 6 9/12/2008 HH H H H What orbitals are used to form this bond? HH H H H What orbitals are used to form these bonds? HH H HH H A. Csp Csp B. B Csp Csp2 C. Csp2 Csp2 D. Csp2 Csp3 E. Csp3 Csp3 F. Cp - Cp 37 A. Csp Csp B. B Csp Csp2 C. Csp2 Csp2 D. Csp2 Csp3 E. Csp3 Csp3 F. Cp - Cp -bond (Csp2-Csp2) C C 38 HH H H H What orbitals are used to form this bond? Would you predict ethylene to be planar or non-planar? non- HH H A. Csp Csp B. B Csp Csp2 C. Csp2 Csp2 D. E. Csp2 Csp3 Csp3 -bond (Csp2-Csp2) H H H H H C H C H H C C -bond (Cp-Cp) C C Csp3 F. Cp - Cp 39 (A) planar (B) non-planar non- Would you predict ethylene to be planar or non-planar? non- Would you predict ethylene to be planar or non-planar? non- H H C C H H H C H C H H H H C C H H H C H C H H (A) planar (B) non-planar non- (A) planar (B) non-planar non- 7 9/12/2008 Would you predict ethylene to be planar or non-planar? nons success! p sp3 a lot of success but still under development. molecular orbital theory valence bond theory from the application of quantum mechanics to H we can derive all of the atomic orbitals as well as their hybrids. H H C C H H C C H CH4 and larger molecules quantum mechanics 44 (A) planar (B) non-planar non- valence bond theory resonance (Lewis) structures resonance (Lewis) structures molecular orbital theory molecular orbital theory valence bond theory H1s H1s antibonding MO H H H1s H1s Orbital Energy H H Orbital Energy 435 kJ/mol (104 kcal/mol) bonding MO H H 45 46 For a C=C bond choose the -antibonding molecular orbital from the following list. (A) (B) (C) C C C molecular orbital theory C C -antibonding molecular orbital C antibonding -bonding molecular orbital C C C C -bonding molecular orbital Csp2 Orbital Energy Csp2 420 kJ/mol (100 kcal/mol) (D) C C -antibonding molecular orbital C 47 C bonding 8 9/12/2008 Do antibonding orbitals play any role in chemistry? Photochemistry! molecular orbital theory valence bond theory resonance (Lewis) structures An alternative view of bonding g molecular orbital theory C C antibonding C C antibonding C2p C C C2p C2p C C C2p Orbital Energy C C bonding Orbital Energy C C bonding 49 50 Draw the best Lewis (resonance) structure for formamide (CH3NO). O H C N H H Draw the best Lewis (resonance) structure for formamide (CH3NO). O H C N H H 3 4 5 6 7 B C N O F Si P S Cl Br I 1. add electrons 2. maximize bonding 3. add formal charges start with correct structure formamide not t H H C H N O formamide nitrosomethane 51 52 Choose the best Lewis (resonance) structure for formamide. O H C N H H 3 4 5 6 7 B C N O F Si P S Cl Br I Choose the structure that is not a resonance structure of formamide. O H C N H H 1. add electrons 2. maximize bonding 3. add formal charges O O H C H formamide O formamide O O N H H Resonance structures are different electronic configurations of the same structure. O A H C N H H BH C N H H C N H DH C N H H A H C BH C N H H C O H C H O N H DH C N H H O H C N H 53 O H H C N H H H O C N H 54 H 9 9/12/2008 Choose the order that has the following structures arranged with respect to increasing stability. 1. maximum bonding (very important) 2. minimize charge separation. 3. O 3 4 5 6 7 B C N O F Si P S Cl Br I Arrange the following compounds in order of increasing stability. 1. maximum bonding (very important) 2. minimize charge separation. 3. O 3 4 5 6 7 B C N O F Si P S Cl Br I charges on electronegative atoms. charges on electropositive atoms. O O N H H charges on electronegative atoms. charges on electropositive atoms. O O N H H H C N H H C 1 H C N H H 2 H C 3 H C N H H H C N H H H A 1 increasing stability 2 3 B 1 increasing stability 3 2 C 2 increasing stability 1 3 increasing stability D 2 increasing stability 3 1 E 3 increasing stability 2 1 F 3 increasing stability 1 2 55 56 Choose the correct geometry for formamide. O C H N H H O C H H N H O C H N H H formamide O H C N H H H O C N H H H O C N H H H A O C N H H H O C N H B C O H H C N H H a true but incomplete story a good story an excellent story 57 58 Why is the nitrogen atom of formamide planar? What is the hybridization of the nitrogen atom ? VSEPR pyramidal O H C N H H H O C N H H Predict the more acidic compound. Draw both products and their resonance structures. O O N H H H C N H + H A sp2 H C formamide VSEPR planar O H C N H B 59 H H H C N H H H H H C N H 60 + H 10 9/12/2008 Predict the major product of the following reaction. Draw both products and their resonance structures. The product with the best resonance structures is predicted to be most stable. O C H N H H O + H H C N H H H or H O C H H Why is the nitrogen atom of formamide planar? What is the hybridization of the nitrogen atom ? VSEPR pyramidal O H C N H H H O C N H H A O H C B O N H sp2 H H formamide VSEPR planar N H H H H C N H O H C H H 61 62 N H Predict the more acidic compound. Draw both products and their resonance structures. Predict the major product of the following reaction. Draw both products and their resonance structures. The product with the best resonance structures is predicted to be most stable. O C O O N H H H C N H + H A H C H N H H O + H H C N H H H or H O C H H A O H C B O N H O H C H H N H N H H H H C N H B H H H C N H H H H H C N H 63 + H H O C H H 64 N H Organic Chemistry, Ch 2 What is Organic Chemistry? who we are NH2 HO Organic Chemistry, how can it be organized? what we eat NH2 HO OH N H serotonin HO O ascorbic acid OH OH N H O N C 4'-pentyl-4-biphenylcarbonitrile what we use 11 9/12/2008 Organic Chemistry, how can it be organized? H Organic Chemistry, how can it be organized? H amines alcohols --NH2 --OH HO N H NH2 alkanes C C amines alcohols ethers --NH2 --OH hydrocarbons --O-- C=O ketones C=O H C alkanes alkenes C C C C aromatics aldehydes aromatics amides many others!! C=O NH2 68 carboxylic acids 67 C=O OH 69 70 Why organize organic chemistry around Functional Groups? amines alcohols --NH2 --OH hydrocarbons alkanes alkenes H C C Why organize organic chemistry around Functional Groups? O HO R + R C Cl R O C O R + H Cl C C alcohol acid chloride O ester O HO CH3 + CH3 C Cl CH3 C O CH3 + H Cl aromatics NH2 HO H methanol acetyl chloride methyl acetate H H HO H O H H+ O Cl CH3 C O C H H N H H HO 71 CH3 cholesterol serotonin cholesterol acetyl chloride cholesteryl acetate 12 9/12/2008 The HO- functional group in different molecules will HOactually have slightly different reactivities. With respect to the environment of the HO group which of the following alcohols, A, B or C, is most like cholesterol? 1 carbon atom 2 carbon atom 3 carbon atom C H OH H H H OH H H H H C OH H H C C C OH C A HO H H HO H H H H HO C C 73 B HO H H H C C H C H H C cholesterol cholesterol C 74 Functional Groups and Organic Synthesis alkane CC C C C O + Li H Li C O O H Functional Groups and Organic Synthesis alkane CC 1. Li C Br 2. C O 3. H2O C C OH C Br Li C + Li 1. 1 C O 2. H2O C + C OH haloalkane CBr H C O H + Br Li Br Li OH C 75 OH H Br C + Br 76 H2O Functional Groups and Organic Synthesis carbonyls CO H C OH N H CrO3Cl Functional Groups and Organic Synthesis carbonyls CO H = pyridinium chlorochromate PCC C O C OH PCC C O haloalkane CBr hydrocarbon CC l l H H C OH H Br C Br 77 C C H2 Pd/C C H C H 78 13 9/12/2008 Functional Groups and Organic Synthesis alkenes CC H Functional Groups and Organic Synthesis alkenes hydrocarbon H C C Br OH C C C C H2 Pd/C C H C H C C Br OH C C + H2O + Br H C OH hydrocarbon CC l l H H C C H2 Pd/C C H C H 79 carbonyls haloalkane alkane PCC C O C OH H Br C Br 1. Li C Br 2. C O 3. H2O C C OH 80 Functional Groups and Organic Synthesis H H Functional Groups and Organic Synthesis PCC H C C O Br H C C Br OH C C C C OH H C OH Br C Br OH C C C C OH H PCC Br C C O Br OH C C H2 Pd/C C H C H C Br 1. Li 2. C O 3. H2O C C OH C C H2 Pd/C C H C H C Br 1. Li 2. C O 3. H2O C C OH OH isolation procedure A floral fragrance 81 Thyme Propose a synthesis of A from compounds containing H 4 carbon atoms or less. PCC H Give the last step of a successful synthesis. H H C C Br OH C OH C C C OH H 1. Li C Br 2. C O 3. H2O C Br C O C C Br C Br OH C C C C OH H PCC Br C C O Br OH C C H2 Pd/C C H C H C C OH C H2 Pd/C C H C H C Br 1. Li 2. C O 3. H2O C C OH OH ? ? ? ? ? A OH ? ? A 14 9/12/2008 Give the last step of a successful synthesis. H H Give the last step of a successful synthesis. H C C O Br H C C Br OH C C C C OH H PCC Br C OH C Br OH C C C C OH H PCC Br C C O Br OH C C H2 Pd/C C H C H C Br 1. Li 2. C O 3. H2O C C OH C C H2 Pd/C C H C H C Br 1. Li 2. C O 3. H2O C C OH OH ? Br Br Br OH 1. Li 2. CH2=O 3. H2O Br A A A + H C H O B + O C + H C H O Give the last step of a successful synthesis. H H C C Br OH C C C C OH H PCC Br C C O Br OH C C H2 Pd/C C H C H C Br 1. Li 2. C O 3. H2O C C OH OH 1. Li 2. CH2=O 3. H2O Br H Br OH A 1. Li 2. Li O 3. H2O 15 ...
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This note was uploaded on 09/04/2009 for the course SBU 101 taught by Professor Debag during the Spring '09 term at SUNY Stony Brook.

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