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Lesson 1: Understanding Carbon Compounds I (Textbook: Chapter 2 page 33-92) 1 Today’s Lecture Topics Covered 10.1 Learning Objectives 10.2 Unique of Carbon 10.3 Isomer 10.4 Functional Group 10.5 Saturated vs Unsaturated 10.6 IUPAC Naming 2 “Organic chemistry is enough to drive one mad. It gives the impression of a primeval tropical forest of the most remarkable things, a monstrous and boundless thicket with no way of escape, into which one may well dread to enter” Frederich Wöhler (1835) 3 Learning Objectives: 1) 2) 3) 4) Identify the multiple bonding character of carbon atoms Identify carbon as the "backbone" of organic chemistry Define hydrocarbon, alkane, alkene, alkyne, cyclic, and aromatic as they relate to organic compounds Classify a hydrocarbon as either saturated or unsaturated compare the geometry of single, double, and triple bonds between two carbon atoms 4 Learning Objectives: 5) 6) 7) 8) Compare the rotational ability in single, double, and triple bonds name and draw structures of alkanes, alkenes, and alkynes up to C10 Recognize and name the substituent groups methyl, ethyl, fluoro, chloro, bromo, and iodo name and draw structures of simple substituted alkanes to C10 Describe the term functional group and relate it to classes of compounds Identify a compound as an alcohol, aldehyde, ketone,ether, organic acid, ester, amine, or amide when given a structural diagram 5 Organic Chemistry 1) 2) 3) 4) 5) The Study of Carbon Compounds (some exceptions: for example carbonates, carbon dioxide, etc.) Example of organics chemical: Food – carbohydrates, fats, protein Clothing – silk, linen, wool, cotton etc. Plastics Pharmaceuticals Detergents and soap 6 Organic vs Inorganic: Differences Organic Inorganic Bonding Covalent Ionic Physical State (room temp) Gas/liquid common Solids common Melting points Tend to be low Tend to be very high Soluble In water Tend to be insoluble Much higher percent soluble Conductivity Nonconductors Conduct in solution and molten 7 Why Is Carbon Unique? 1. 2. Forms four covalent bonds Bonds covalently to: H, O, N, P, S, and all other nonmetals (except noble gases) 3. Carbon atoms join to form: Chains and Rings H2 C CH2 CH3CH2CH2CH3 H2C H2C CH2 8 Why Is Carbon Unique? 4. Carbon can form multiple bonds to itself, oxygen, and nitrogen. Example: C-C (single bond) C=C (double bond) C=C (triple bond) 9 Why Is Carbon Unique? 5. Many carbon compounds exist in the form of isomers. Isomers are compounds with the same molecular formula but different structures. An isomer example: A, B, and C all are C4H10 but have different structures. Example: 10 CH3CH2CH CH2 A CH3CH CH CH3 B CH2 CH2 C CH2 CH2 11 Families of Compounds: Hydrocarbons Hydrocarbons contain only carbon and hydrogen. They are nonpolar molecules and consequently are not soluble in water but are soluble in typical nonpolar organic solvents like toluene or pentane. Hydrocarbons are constructed of chains or rings of carbon atoms with sufficient hydrogens to fulfill carbons need for four bonds. 12 - Classification Hydrocarbons Aliphatic -nonbenzenoid rings -Example: Alkanes, alkenes, alkynes & their derivative Aromatic Benzene ring Example: Benzene (C6H6) Naphthalene (C10H8) 13 14 Functional Group Part of an organic molecule where chemical reactions take place Composed of an atom or group of atoms Replace a H in the corresponding alkane Provide a way to classify organic compounds Let’s see some example in the next slide 15 Functional Group Functional group Class of organic compound C-C (single bond) Alkane C=C (double bond) Alkene CH2=CH2 ethene C=C (triple bond) Alkyne CH2 ethyne Arene C6H5CH3 methylbenzene - OH Alcohol and Phenol CH3OH methanol -O- Ether CH3-O-CH3 -halogen, -F, -Cl, -Br Haloalkane CH3CH2Cl chloroethane (benzene ring) Examples CH4 methane, C2H6 ethane 16 Functional Group Functional group Class of organic compound Aldehyde Examples ethanal Ketone propanone -COOH Carboxylic acid CH3COOH ethanoic acid -COO- Ester -NH2 Amine CH3NH2 methylamine -CONH2 Amide CH3CONH2 ethanamide CH3COOCH3 17 General Formulae Homologous series: series of compounds with similar chemical properties, each member differs from the previous one by the addition of a –CH2- group. The general characteristics of a homologous series are: 1) same functional group and similar chemical properties. 2) differs from the next in the series by a –CH2- group. 3) may be prepared by similar methods. 4) The physical properties- show a progressive change with increasing relative molecular mass. 5) contain the same elements and can be represented by the same general formula. 18 General Formulae O Homologous CH C NH series Alkanes Cycloalkanes Alkenes Cycloalkenes Alkynes Haloalkanes Alcohols n 2n+1 2 General formula CnH2n+2 CnH2n CnH2n CnH2n-2 CnH2n-2 CnH2n+1 X (X= Cl, Br, I) CnH2n+1 OH CnH2n+2O 19 General Formulae O Homologous series CnH2n+1C General formula NH2 Aldehyde CnH2nO Ketones CnH2nO Carboxylic acids CnH2nO2 CnH2n+1 COOH Esters CnH2nO2 Amine CnH2n+1 NH2 Amide CnH2n+1 CONH2 20 General Formulae The general formula for an organic compound can also be written by using the symbol R to represent the alkyl group, CnH2n+1 or the phenyl group, C6H5. (R’ and R’’ represent two alkyl groups. The alkyl groups can be the same or different.) The phenyl group (- C6H5) has the structural formula of: 21 General Formulae Homologous series General formula Alkanes RH Aldehydes RCHO Ketones R’COR’’ Alcohols ROH Carboxylic acids RCOOH Esters R’COOR’’ Amines RNH2 Amides RCONH2 22 Systematic Naming 1) 2) 3) The IUPAC (International Union of Pure and Applied Chemistry) is responsible for chemistry names. In the IUPAC system, the chemical name of an organic compounds has three parts: prefix, parent and suffix The prefix of the chemical name gives information about the substituent present, the parent gives the number of carbon atoms present in the molecule the suffix gives the name of the homologous series. 23 Systematic Naming Example: IUPAC name for BrCH2CH2COOH is 3–bromopropanoic acid Prefix: bromo Parent: propan Suffix: oic 24 Saturated and Unsaturated Compounds Saturated compounds (alkanes) have the maximum number of hydrogen atoms attached to each carbon atom Unsaturated compounds have fewer hydrogen atoms attached to the carbon chain than alkanes Unsaturated compounds contain double or triple bonds 25 Unsaturated Hydrocarbons Molecules contain one or more carbon-carbon double (C=C) or triple (C≡C) bonds There are three classes of unsaturated hydrocarbons: 1. alkenes and cycloalkenes, CnH2n 2. alkynes and cycloalkynes, CnH2n-2 3. aromatic hydrocarbons 26 Alkanes, CnH2n+2 Contain C and H only Contain single bonds C-C Have 4 bonds to every carbon (C) atom Are nonpolar H C H H H C H H 109.5 o 27 Alkanes, CnH2n+2 The bonding around each carbon atom is tetrahedral, so all bond angles are 109.5°. As a result, the carbon atoms in higher alkanes are arranged in zig-zag rather than linear patterns. H C H H H C H 109.5 o H 28 General Formulae IUPAC Name # Carbon Molecular formula Structural formula /Condensed formula Methane 1 CH4 CH4 Ethane 2 C2H6 CH3CH3 Propane 3 C3H8 CH3CH2CH3 Butane 4 C4H10 CH3CH2CH2CH3 Pentane 5 C5H12 CH3CH2CH2CH2CH3 Hexane 6 C6H14 CH3CH2CH2CH2CH2CH3 Heptane 7 C7H16 CH3CH2CH2CH2CH2CH2CH3 Octane 8 C8H18 CH3CH2CH2CH2CH2CH2CH2CH3 Nonane 9 C9H20 CH3 CH2 CH2CH2CH2CH2CH2CH2CH3 Decane 10 C10H22 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 29 Alkane- IUPAC Names Before learning the IUPAC rules for naming alkanes, the names and structures of eight alkyl groups must be learned. These alkyl groups are historical names accepted by the IUPAC and integrated into modern nomenclature. 30 Alkyl Groups H H C H H H H C or CH3 H An alkyl group is an alkane with one hydrogen atom removed. It is named by replacing the ane of the alkane name with -yl. Methane becomes a methyl group. 31 All six hydrogens on ethane are equivalent. Removing one H generates the ethyl group. HH HCCH HH CH3 CH2 CH2 CH3 C2H5 32 Synthetic polymers provide a wide variety of items that we use every day. 33