Organic Chemistry 1 Lecture Notes (Ain Shams University) PDF

2 Lecture nd Organic Chemistry 1 Faculty of Pharmacy Ain Shams University ( General ) Introduction part 2 Dr Yousry Academy ‫ﻻ ﺗـﺨﻒ ﻣﻦ اﻟﻮﺣﺶ‬ 2024 - 2025 Dr. Yousry Academy Dr Yousry’s Community mohamed yousry ...

2 Lecture nd Organic Chemistry 1 Faculty of Pharmacy Ain Shams University ( General ) Introduction part 2 Dr Yousry Academy ‫ﻻ ﺗـﺨﻒ ﻣﻦ اﻟﻮﺣﺶ‬ 2024 - 2025 Dr. Yousry Academy Dr Yousry’s Community mohamed yousry  Lecture 2 Introduction to organic chemistry 1) Hybridization SP3 SP2 1 SP 2) Co-ordinate bond 3) Types of interaction forces I. Dipole Dipole attraction II. Non- polar attraction " Van Der Waal Dispersion forces " or London dispersion III. Hydrogen bonds o Intermolecular HB o Intramolecular HB 4) How to draw dot line 1  Hybridization Definition: Mixing of atomic orbitals of the same shell to give New hybrid orbitals. ‫ عزيزى الطالب ركز عشان الحتة دى عنيفة مش عايزك تحفظ‬ 1. Hybridization must be between 2 unequal atomic orbitals in energy. Then we obtain hybrid orbitals. The number of mixed atomic orbitals = The number of produced hybrid orbitals. 2.Hybridization may be: 𝑆𝑃 3 → All single bonds 𝑆𝑃 2 → In double bonds SP → In triple bonds 3. Formed bond may be between: 1. Atomic orbital & atomic orbital 2. Atomic orbital & hybrid orbital 3. Hybrid orbital & hybrid orbital 4. The New hybrid orbital has specific energy intermediate between the two mixed orbitals. 2  Methane 𝐂𝐇𝟒 Shape: tetrahedral Angle: 109.5° Hybridization: 𝑆𝑃 3 2p p 1. promotion ‫عندى أوضة فاضية‬ 6 promotion ‫اعمل‬ ‫و أحط واحد فيها‬ “Acc. To Linus Pauling” 2p p Half filled orbitals - Methane results from the overlap of the carbon 2. hybridization for equivalent. 𝑆𝑃 3 orbitals with the four 𝑆𝑃3 hydrogens. 1s orbitals to give four 𝜎 (head to head) which have the same length & the same SP3 bond angles (109.5o) “identical”. - 4 sigma bonds between C & H (SP3) (1S) 3  Ethane 𝐂𝟐 𝐇𝟔 2p 1.10 Aͦ 1.54 Aͦ 1. promotion 2p Shape: Tetrahedral Angle: 109.5 ° 2. hybridization 𝑆𝑃3 Hybridization: SP3 3 sigma bond between C & H SP2 SP3 1S 1 sigma bond between C & C SP3 SP3 4  Ethene (Ethylene) 𝐂𝟐 𝐇𝟒 Shape: trigonal planar Angle: 120° 2p Hybridization: 𝑆𝑃 2 1. promotion ‫عندى أوضة فاضية‬ promotion ‫اعمل‬ ‫و أحط واحد فيها‬ 6 2p 2. hybridization - The carbon in ethene forms 2 bonds with each 𝑆𝑃2 other this is called double bond - 4 sigma bonds between C & H SP2 1S - 1 sigma bond between C & C (head-on overlap) SP2 SP2 SP2 - 1 pi bond between C & C (side-on overlap) 2P3 2P3 5 Note: The unhybridized P orbital is perpendicular to these SP 2 orbitals. 5  Ethyne (Acetylene) 𝐂𝟐 𝐇𝟐 Shape: linear Angle: 180° Hybridization: 𝑆𝑃 2p 1. promotion ‫عندى أوضة فاضية‬ promotion ‫اعمل‬ - The carbons in ethyne form 3 bonds with each other. This is called a ‫و أحط واحد فيها‬ triple bond (one sigma + 2 pi ). Note: The two unhybridized P orbitals are perpendicular to each other, and both are perpendicular to the SP orbitals. 2p 6 - Head to head overlap of one SP orbital with second carbon. SP orbital form sigma bond. 2. hybridization - 2 sigma bonds between C & H (head-on overlap) SP SP 1S - 1 sigma bond between C & C SP SP 2p - 2 pi bonds between C & C (side-on overlap) P P 6  Ammonia 𝐍𝐇𝟑 7 Hybridization Sp3 promotion ‫معملناش‬ - Bond angle: 107.3 not 109.5 why? ‫عشان مفيش خانة فاضية‬ Because the repulsion between the lone pair and the bonding pair is greater than the electron repulsion between two bonding pair. pair - 3 sigma bonds between N & H SP3 1S - 1 lone pair in SP3 orbital 7 7  Water H2O Shape: Tetrahedral Angle: 104.5° Hybridization: SP3 - Bond angle is 104.5 due to the electron repulsion 3 between the two lone pairs & the bonding pair. - 2 sigma bonds between O & H SP3 1S - 2 lone pair in SP3 orbitals 8  SP3 Carbon SP2 Carbon SP Carbon Orbitals surrounding Carbon Shape or Geometry Tetrahedral or Pyramidal Planar or Triangular or Trigonal Linear Saturated carbon i.e. all Saturation Unsaturated carbon i.e. has Pi Unsaturated carbon i.e. has Pi bonds are sigma bonds. bond. bond. Carbon is surrounded by two Carbon is surrounded by Carbon is surrounded by three Bonds sigma bonds and two Pi four sigma bonds sigma bonds and one Pi bond bonds Bond angle 109.5° 120° 180° 27 9  type of hybridization ‫قانون العفريت لمعرفة ال‬ No. of lone pair + no. of atoms directly attached to the central atom. No. of lone pairs + hybridization examples No. of bonded atoms 2 SP BeCl2 3 𝑆𝑃 2 BF3 4 𝑆𝑃 3 𝐶𝐻4 , 𝑁𝐻3 5 𝑆𝑃 3 𝑑 𝑃𝐶𝑙5 6 𝑆𝑃 3 𝑑 2 SF6 Exercise: 10  Advanced hybridizations If atom Show the bonding of C in each of the following: Example 1: Example 2: Try by yourself:.... 11  C-C C-C C-H C-H S Character Bond Length Bond Strength Bond Length Bond Strength 𝑆𝑃3 𝑆𝑃3 1𝑆 Longer but still 𝜎 25 % 𝐶𝐻3 − 𝐶𝐻2 − 𝐻 much stronger than Weakest Longer Weakest 𝜋 𝑆𝑃2 𝑆𝑃2 1𝑆 33.33 % 𝐶𝐻2 = CH − H Shorter Stronger Shorter Stronger SP SP 1S 50 % CH ≡ C − H Shorter Strongest Shortest Strongest -As (S) character increase, E.N of C increase and bonds become shorter and stronger. So > (Shorter) > (Shorter) & > (Stronger) > (Stronger) 𝜎 𝜋 But still stronger than hybridization applications ‫نهاية ال‬ − = Note: C-H sigma bond is shorter and stronger than a C-C sigma bond. This is because the S orbital of hydrogen is closer to the nucleus than is the SP3 orbital of carbon. Consequently the nuclei are closer together in a bond formed by SP3-S overlap than they are in a bond formed by SP3-SP3 overlap. 12  Ionic Bond Remember types of bonds: Covalent Bond ‫من الحصة اللي فاتت‬ Coordinate Bond ‫اآلن‬ Lewis ‫تذكر‬ 1) 2) 3) 4) 5) 6) 7) 13 3- Co-ordinate bond (dative covalent bond): "‫"الحصة الثانية‬ " It is the sharing of 2 electrons but one atom → complete donor of 2 electrons. And one atom → complete acceptor of 2 electrons (Atom has its own.. pair) (Atom has a vacant orbital).. A + B A—B Covalent bond A: + B A→B Coordinate bond Donor Acceptor atom atom A+—B- has has lone vacant pair orbital 14 Examples: 1. Ammonia boron trifluoride Formal charge  2. Ammonium ion  3. Ammonium Aluminum trichloride  15 Chemistry of Carbon: EX: EX: EX: Chemistry of Oxygen: EX: EX: NB: : Chemistry of Nitrogen: EX: NB: : 16  Types of interaction forces Organic compounds interact by attraction or repulsion with each other according to their nature. I.Dipole Dipole attraction: Occurs in polar compounds which are oriented with the negative poles near to the positive poles of other molecules. Example: 1. 𝐶𝐻3 − 𝐶𝑙 Dipolar attraction between molecules II. non-polar attraction “Van Der Waal” Dispersion forces or London dispersion: - It occurs in non - polar molecules, when they become very close to each other, they will acquire induced polarization leading to dipolar attraction. - The weakest type of attraction because in the molecule it doesn't exist as negative and positive pole. Induced polarization after the molecules became close to each other which make uneven distribution of electrons at the surface Van der waal induced polarization results in molecular attraction in n-octane 17 III. Hydrogen bonds: - Occurs between H atom and (N, O, F) which have high E.N (& small in size) and H will acquire partial positive charge. - H makes strong interaction with the nearest negative atom of the same molecule or of another molecule. -The power of such interaction is equal to 10 - 15 % of the power of sigma bond (this attraction is very powerful). It can be either Intermolecular HB Intramolecular HB -Occurs between molecules that -Occurs in molecules having O-H have H-O or H-N or H-F bonds. or N-H groups close to other negatively charged atoms in same molecule. Example 1 Example 2 Water Water salicylaldehyde Example 3 Alcohol Water Example 4 O-Nitrohenol p-nitrophenol (Intermolecular hydrogen bonding) 18  Intermolecular H-bond effect on molecules: Intramolecular H-Bond effect on molecules: 1. Increase B.P& M.P? due to the high 1. Decrease B.P & M.P? attraction forces between these molecules. Because chelation separates the molecules resulting in a Water boiling point is 100ºC "high"? decrease in their attraction with each other. Intermolecular H-bond between 2. Decrease solubility of molecules in water water molecules leads to ↑ B.P. 2. Increase the solubility and miscibility in each other due to the formation of intermolecular HB between their molecules Intramolecular hydrogen Intramolecular hydrogen bonding in ortho hydroxy Alcohol is miscible with water benzaldehyde (salicylaldehyde) bonding in ortho nitrophenol Note: R Chelation makes a cycle that shouldn’t exceed 5 or 6 member rings. Intermolecular H-bond between water molecules & Alcohol molecules ↑ Miscibility Why o-nitrophenol has lower melting point than p- nitrophenol? H-Bonding is also important in biological systems, where they affect the binding of substrates to their Note: According to strength: H- bond > Dipole Dipole > Non polar attraction targets. 19  Dot line method examples: 1) 2) 3) C CH2 H3C C CH3 4) 5) 6) 20 7) 8) 9) 10) 21  Try by yourself: 1) Fluorine has a lower electronegativity than a) Oxygen 33 b) Chlorine c) Lithium d) None of these answers is correct 2) Which molecule of these contains an SP2 hybridized atom? a) BeH2 b) NH3 c) BH3 d) CO2 e) c & d 3) Which of the following statements is true: a) The more P character, the shorter the bond b) The more S character, the longer the bond c) The more S character, the stronger the bond d) The more P character, the stronger the bond 4) orbitals that are equal in energy are called: a) Degenerate b) Filled c) Polar d) Nodes 5) Which molecules have the strongest intermolecular forces? a) BF3 b) H2S c) NH3 d) H2 22 6) Which of the following orbital diagrams represents phosphorus which has (15) electrons? a) b) c) d) 7) Which representation for Lewis structure of nitrate anion (NO3-) is correct? a) b) c) d) 8) Which set of hybridization states of (C1,C2,N and O) of the following molecule is correct ? a) C1:Sp3, C2:Sp2, N:Sp2, O:Sp3 b) C1:Sp3, C2:Sp2, N:Sp2, O:Sp CH c) C1:Sp2, C2:Sp3, N:Sp2, O:Sp2 d) C1:Sp2, C2:Sp2, N:Sp2, O:Sp2 9) Which set of approximate bond angles at C1,C2, and C3 is correct for the following structure? a) C1:109.5o, C2:120o, C3:180o b) C1:120o, C2:120o, C3:180o c) C1:109.5o, C2:120o, C3:120o d) C1:120o, C2:120o, C3:120o 23  10) The number of sigma bonds and Pi bonds in: a) 13∂, 3 ∏ b) 8 ∂, 3 ∏ c) 4 ∂, 4 ∏ d) 16 ∂, 4 ∏ 11) Which of the molecules below would not form hydrogen bonds? a) CH3OH b) CH3OCH3 c) CH3COOH d) NH3 e) None of these would form hydrogen bond 12) Which of the following can form strongest intermolecular hydrogen bonds? a) CH3OH b) CH3SH c) CH3C N d)CH3–C–CH3 ‖ O 13) In overlapping of 1S, 2Px, 2Py, 2Pz with other atomic orbitals 1S, 2Px, 2Py, 2Pz, the number of produced molecular orbitals are a) 4 b) 8 c) 16 d) 20 24  Which is Right – Which is wrong ? and why? 7N 34 31 Indicate the bond type in the following molecules: a) NaF b) HCl c) Cl2 d) CH4 Describe bonding of the following molecules in terms of atomic orbitals involved and predict bond angles: 3) : 2).... 1).... 25 Indicate the kind of molecular orbital (sigma, pi) that results when the orbitals are combined as indicated: Describe the bonding in the following molecules the type of hybridization and predict all bond angles: 10 26