n -butyl sec -butyl isobutyl tert -butyl 54 Chem 1AA3 Substituents Vinyl groups Allyl groups Phenyl groups Example: Allyl acetate
1 55 Chem 1AA3 Diagnostic iClicker Question What is the name of this compound? (a) (b) (c) (d) (e) PH 56 Chem 1AA3 Diagnostic iClicker Question What is the name of this compound? (a) (b) (c) (d) (e) PB 57 57 Chem 1AA3 Diagnostic iClicker Question What is the name of this compound? (a) (b) (c) (d) (e) JV 58 58 Chem 1AA3 Diagnostic iClicker Question What is the name of this compound? (a) (b) (c) (d) (e) HS Reactions of Alkanes Section 26-2 60 Chem 1AA3 Concept Check C 8 H 18 (l) + O 2 (g) ? 1) What are the products of the reaction at 298K?2) Write a balanced chemical equation3) Predict the signs of ∆H, ∆S and 4) What type of reaction is shown? ∆ G
1 61 Chem 1AA3 Concept Check: Solution 62 Chem 1AA3 Halogenation CH 4 X 2 Light or heat CH 3 X + HX + CH 3 -CH 3 63 63 Chem 1AA3 Halogenation H 3 C· + Cl· → Cl· + Cl· → H 3 C· + H 3 C· → Cl-Cl → ∆ or h ν H 3 C-H + Cl· → H 3 C· + Cl 2 → Applicable also for F 2 (often explosive), Br 2 , I 2 (slow) 64 64 Chem 1AA3 Grignard Reagent R X Mg Et 2 O R MgX Look at the change in oxidation state of the Mg: Mg(0) Æ Mg(II) Question: What gets reduced? Bonding in alkanes Hybridization Section 11-3 66 Chem 1AA3 Review: Electronic Structure and Bonding The following section, up to "Review: p-orbitals", is assumed knowledge and will not be discussed in class. The Atom: A dense nucleus surrounded by a much larger extranuclear space
1 67 Chem 1AA3 Review: Principal Energy Levels • Electrons are confined to shells defined by the principal quantum number (n) • n = 1, 2, 3 … • Each shell can contain 2n 2 electrons • The lower the value of n-the lower the energy of the shell (nearest to the nucleus) 68 Chem 1AA3 Review: Orbitals • Shells are divided into sub-shells labelled s, p, d, f • p, d, and f orbitals are further divided up based on their spatial orientation 69 69 Chem 1AA3 Review: Orbitals in Shells Shell Orbitals in that shell n = 1 1 s n = 2 2 s , 2 p x , 2 p y , 2 p z n = 3 3 s , 3 p x , 3 p y , 3 p z , + 5 3 d 70 70 Chem 1AA3 Review: Electron Configuration Three principles/rules are used to determine the electron configuration: Aufbau Principle Pauli Exclusion Principle Hund’s rule 71 Chem 1AA3 Review: Orbitals (subshells) • Each type of orbital (s, p, d, f) has a distinct shape • The shape represents the probability of finding an electron (quantum mechanics) • Organic chemists are interested in shells 1, 2, and sometimes 3 72 Chem 1AA3 Review: s-orbitals Spherical:
1 73 Chem 1AA3 Review: p-orbitals 3 of them: p x , p y , p z 74 Chem 1AA3 Example: Carbon The outer most electrons of atoms (valence electrons) govern the chemical and physical properties 75 75 Chem 1AA3 p-Orbital Shapes • The p-orbitals in carbon are at 90 • Atoms bonding to a carbon atom should therefore be situated at 90 76 76 Chem 1AA3 Methane - CH 4 • Problem: the shape of methane is tetrahedral (AX 4 ) • 77 Chem 1AA3 Hybridization • Comes from the word hybrid which means something of mixed origin or composition • Hybrid orbitals arise by combination of atomic orbitals within an atom 78 Chem 1AA3 sp 3 Hybridization (section 11-3)
1 79 Chem 1AA3 sp 3 Hybridization 80 Chem 1AA3 sp 3 Hybridization The number of hybrid orbitals is equal to
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