Transcript CHAPTER 1
Organic Chemistry Organic chemistry may be defined as the chemistry of carbon compounds. However, simple carbon-containing compounds (such as carbon monoxides, carbon dioxide and hydrogen cyanide) and carbon-containing salts (such as carbonates and cyanides) are not generally considered to be organic compounds. They are usually studied in inorganic chemistry courses. Over 96% of known chemical compounds contain carbon, these are known as organic compounds *Differences between Organic and Inorganic Compounds Properties *Structure *solubility Organic chemistry In organic chemistry *Contain carbon as the principle *Study of compounds that do not element contain carbon as the principal element *Contain carbon and Carbon-carbon or *Usually do not contain carbon and Carbon-Hydrogen covalent bonds never contain carbon-carbon or carbonHydrogen covalent bonds. *Usually dissolve in organic solvent *Usually dissolve in water *Boiling point *low *High *Melting point *low *High *chemical bond *Covalent bond *Ionic bond 1.Using the table below, check a compound is organic or inorganic. (5 marks ) Compound Organic Inorganic Compound Organic Inorganic CO CH4 CH3OH NaHCO3 HCl C6H12O6 NH3 Na2CO3 CO2 K2Cr2O7 CrS Ca(OH2) C2H4 Co(NO3)2 C4H10 C19H28O2 C8H18 CH3OCH3 Cu2O C18H21NO3 Cr2O3 CH3COOH CHCl3 CH3NHCH3 Chemical bond and valence Valence : number of electron which place in highest shell Type of chemical bond Ionic bond Covalent bond Ionic Bond Between atoms of metals and nonmetals with very different electronegativity Bond formed by transfer of electrons. Examples; NaCl , CaCl2 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions. COVALENT BOND bond formed by the sharing of electrons Covalent Bond Between nonmetallic elements of similar electronegativity. Formed by sharing electron pairs Examples; O2, CO2, C2H6, H2O, SiC type of covalent bond Signal covalent bond triple covalent bond double covalent bond H Ethane ethene C C Acetylene H Electron Configuration of Carbon Why is CARBON so special? Atomic number = 6 6 protons, 6 electrons 1s2 2s2 2p2 electron structure Valence of 4 electrons Need 8 electrons to fill valence shell Form 4 bonds with other atoms Can combine with 1, 2, 3 or 4 other C atoms Single, double, triple bonds Each bond consists of 1 electron from carbon & 1 electron from bonding atom Importance of carbon atom 1. 2. 3. 4. 5. Basis for all life Form stable covalent bonds to other carbon atom Can form single ,double and triple bond Long carbon chain can be produced Will bond with many other element. Carbon contain 2electron paired in first shell(No sharing electron) No sharing electron 1S2 Carbon contain 4 electron in Second shell No sharing electron 2S2 Sharing electron 2P2 Carbon atom must contain 4 electron unpaired to formation 4bond to become more stable this acure by hybridzation Hybridization: over lab between orbital's of electron to formation new orbital contain unpaired electron formation more bond Some compound contain signal bond c bond C Some compound contain double bond C bond bond c Some compound contain trible bond H C C H 2 bond C bond c Type of hybridization SP3 hybridization SP2 hybridization SP hybridization H C C H Ethane Ethene Acetylene 3 SP Ethane hybridization Electron configuration of carbon only two unpaired electrons should form s bonds to only two hydrogen atoms Lead to hybridization occur Hybridization of atomic orbitals Is overlap of the s and p orbital's occur in two steps . 1 2p excite one electron 2s . . 2 mix orbitals 2s 2p 1s + 3P = SP3 H bonds H bonds . . bonds . . bonds . .C. . H H 2 SP hybridization Ethene Hybridization of atomic orbitals Is overlap of the s and p orbitals occur in TWO steps 2p 1 . excite one electron 2s . 2 mix orbitals 2s 2p . 1s + 2p = sp2 sp2 Orbital Hybridization Π 2 sp2 c c σ σ H σ p H σ σ H H SP hybridization Ethane sp Hybridization and Bonding in Acetylene H C C H Acetylene Hybridization of atomic orbitals Is overlap of the s and p orbitals occur in three steps 1 2p . excite one electron 2s . 2 mix orbitals 2s 2p 1S 1P . SP sp Orbital Hybridization p 2 sp2 c σ H σ Π c Π σ H Classification of organic chemistry by functional group Hydrocarbon : These compound which contain carbon and hydrogen H C C H classification hydrocarbon Aliphatic alkanes Cyclo alkanes Alkenes Alkyenes Aromatic Benzene The IUPAC Nomenclature of Alkanes IUPAC "International Union of Pure and Applied Chemistry" names The IUPAC system is based upon a series of rules which enable us to explain the structure of a compound from its name. We should start by learning the names of 10 simplest straight chain alkanes. i- Locate the longest continuous chain of carbon atoms ii- Indicate the position of a side chain(replacement group) by the lowest possible number. replacement group 5 4 3 1 2 3 2 4 1 5 √ x replacement group may be alkyl group or another atom(Halogen) alkyl group) contain from hydrogen atom removed from alkane CH4 –H ( Methane) CH3- = (methyl ) CH3CH3 ( ethane ) CH3CH2- = ethyl CH3CH2CH3 (Propane)CH3CH2CH2- = Propyl Replace ane from alkane to yl The substituent groups are listed alphabetically When two or more substituents are identical, indicate this by the use of the prefixes di-, tri-, tetra-, and so on. Physical Properties of alkane Non polar molecule No soluble in water Low melting point Low boiling point first four members (C1–C4 )are gases C5-C17are liquids and above C17 are solid Chemical Properties of alkane Preparation of alkane Hydrogenation of alkanes: Reduction of alkyl haled 1-hydrolysis Girgnard reagent R-X +Mg RMgX +H2O R-H CH3CL + MgCH3MgCL+H2OCH4 Reduction by metal and acid R-X +Zn+ H+ R-H+Zn+2+XCH3CH2CL +Zn+2+H+CH3CH3+Zn+2+XReaction of alkane HALOGENATION CH3 –CH-CH3 CH3 ISO BUTANE CL2 CH3 CH3 –CH-CH2CL ISO BUTYL CHLORIDE + CL CH3 –CH-CH3 CH3 TERT BUTYLCHLORIDE Reduction by metal and acid Reaction of alkane HALOGENATION CH3 –CH2-CH3 Propane Br2 CH3 –CH2-CH2Br 1Bromo Propane + Br CH3 –CH-CH3 2Bromo Propane . Alkenes are unsaturated hydrocarbon, they contain a carbon-carbon double bond which general formula . Nomenclature: Count the number of carbon atoms in the longest continuous carbon chain containing the double bond Change the ending from –ane by –ene Indicate the position of the double bond by the lowest possible number CH2 = CH - CH2 - CH3 1butene CH3CH=CHCH3 2 butene Alkynes Alkynes contain a carbon-carbon triple bond, these compounds they have the general formula CnH2n-2 Nomenclature: Count the number of carbon atoms in the longest continuous carbon chain containing the triple bond Change the ending from –ane by –yne Indicate the position of the triple bond by the lowest possible number