Chapter 1 Carbon as the Basis of Organic Chemistry

Transcription

1 Chapter 1 Carbon as the Basis of rganic Chemistry Clayden, Greeves, Warren, Wothers, rganic Chemistry, xford University Press, 2001, Chapter 4, pp Arnaud, Chimie rganique, Paul Arnaud, Dunod Editeur, 2009, Chapitre 4, pp

2 Definition of rganic Chemistry organic chemistry is the chemistry of carbon-containing molecules (compounds) organic molecules contain carbon covalently bonded to other (non-metallic) elements group 4 Ia IIa IIIa IVa Va VIa VIIa VIII Ib IIb IIIb IVb Vb VIb VIIb Wasserstoff 2 e elium 2 3 Li 6.94 Lithium 4 Be 9.01 Beryllium 2nd period 5 B Bor 6 C Kohlenstoff 7 N Stickstoff Sauerstoff 9 F Fluor 10 Ne Neon 3 11 Na Natrium 12 Mg Magnesium 13 Al Aluminium 14 Si Silicium 15 P Phosphor 16 S Schwefel 17 Cl Chlor 18 Ar Argon 4 19 K Kalium 20 Ca Calcium 21 Sc Scandium 22 Ti Titan 23 V Vanadium 24 Cr Chrom 25 Mn Mangan 26 Fe Eisen 27 Co Cobalt 28 Ni Nickel 29 Cu Kupfer 30 Zn Zink 31 Ga Gallium 32 Ge Germanium 33 As Arsen 34 Se Selen 35 Br Brom 36 Kr Krypton 5 37 Rb Rubidium 38 Sr Strontium 39 Y Yttrium 40 Zr Zirconium 41 Nb Niob 42 Mo Molybdän 43 Tc Technecium 44 Ru Ruthenium 45 Rh Rhodium 46 Pd Palladium 47 Ag Silber 48 Cd Cadmium 49 In Indium 50 Sn Zinn 51 Sb Antimon 52 Te Tellur 53 I Iod 54 Xe Xenon 6 55 Cs Cäsium 56 Ba Barium 57 La Lanthan 72 f afnium 73 Ta Tantal 74 W Wolfram 75 Re Rhenium 76 s smium 77 Ir Iridium 78 Pt Platin 79 Au Gold 80 g Quecksilber 81 Tl Thallium 82 Pb Blei 83 Bi Bismut 84 Po Polonium 85 At Astat 86 Rn Radon 7 87 Fr Francium 88 Ra Radium 89 Ac Actinium 104 Rf Rutherfordium 105 Db Sg Bh s 109 Mt carbon is in 4 th group of the 2 nd period of the PSE; 4 valence electrons on 2 nd shell for bonding carbon is tetravalent, can connect with a maximum of four bonds (electron pairs) to other atoms 18

3 The Time-Independent Schrödinger Equation electrons (waves) around a nucleus, have to fulfill the time-independent Schrödinger equation Ĥ = E Schrödinger equation is a differential equation that describes the allowed states (stationary state wave functions ψ) of an electron in the field of an atomic nucleus if the amilton operator Ĥ (amiltonian) acts on a wave function ψ and the result is proportional to ψ, then ψ is an allowed stationary state and the proportionality constant (Eigen value) is its energy E in one dimension: h2 Ĥ (x) = 8º 2 m d 2 (x) dx 2 +V (x) (x) = E (x) in three dimensions: h2 Ĥ (r ) = 8º 2 m r2 (r ) +V (r ) (r ) = E (r ) µ Ĥ (r ) = 2 8º (r ) +V (r ) (r ) = E (r ) 2 is the Laplace operator, V(r) is potential energy, m is electron mass, h is the Planck constant 19

4 Quantum Numbers and Exclusion Principle the different allowed stationary states ψ are described by unique combinations of quantum numbers Name principal QN n azimuthal QN l magnetic QN m spin QN s electrons 1s ½, ½ 2 2s ½, ½ 2 2p , 0, 1 +½, ½ 6 3s ½, ½ 2 3p , 0, 1 +½, ½ 6 3d , +1, 0, 1, 2 +½, ½ 10 each orbital described by unique set of quantum numbers n, l, and m n, l, m correspond to electron energy, angular momentum, angular momentum vector component each orbital then filled with up to two electrons with different spin QN s (Pauli exclusion principle) 20

5 Representations of Atomic rbitals atomic orbitals are space where the electron has a certain non-zero probability to be observed 1s 2s 2p z 2p x 2p y 3s 3p z 3p x 3p y 3d z 2 3p xz 3p yz 3p xy 3p x 2 y2 pictorial representations of atomic orbitals use ψ 2 representing the probability density to find electron approximate representations of contour surfaces with given probability density ψ 2 = const. representations often use color coding to show phase (sign) of ψ itself (important for bonding) 21

6 Valence Electrons and the Electronic Configuration of Carbon atomic orbitals filled with electrons starting from low to high energy states (Aufbau principle) E 2p x 2p y 2p z 2p z 2p x 2p y 2s 2s 1s 1s valence shell is outer-most, highest-energy shell (highest principal QN n) filled with electrons only valence shell and valence electrons relevant for chemical bonding and reactions electronic configuration of carbon in the ground state 1s 2 2s 2 2p 2 22

7 Modifications (Allotropes) of Carbon Graphite Fullerenes, Nanotubes Diamond every carbon has 3 neighbors every carbon has 4 bonds every carbon has 3 neighbors every carbon has 4 bonds every carbon has 4 neighbors every carbon has 4 bonds carbon is always tetravalent (connected with four bonds to other atoms) variable coordination geometry: tetrahedral (4 neighbors), trigonal (3 neighbors), linear (2 neighbors) 23

8 Different Types of Chemical Formulae trivial name IUPAC name molecular formula condensed formula structure formulae isobutane 2-methylpropane C₄₁₀ C₃ -C(C₃ )-C₃ C C C C 3 C C 3 C3 acetone propan-2-one C₃6 C₃ -C()-C₃ C C C 3 C C 3 acetic acid ethanoic acid C₂₄₂ C₃-C()- C₃C C C 3 C benzene benzene C₆₆ C₆₆ C C C C C C styrene 1-phenylethene C₈₈ C₆₅-C=C₂ Base C C C C C C C C C 2 24