Chapter 21: Phenomena Phenomena: Below are the names and pictures of several organic compounds. Can you determine the naming conventions of these compounds? What are the b) CH3 a) H CCH 2 2CH2 CH3 c) H CCH names of the CH 3 3 H C CH ethane following H3CCH2CH2 2 2 heptane d) structures and CH2 CH2 H3CCH2CH2CH3 methylcyclopentane butane why? e) CH2CH2 g) f) CH3 H2C CH2 H3C CH H C CH CH 2 2 2 H3CCHCHCH2 3 H C CH CH CH 2 2 2 2 CH cyclobutane cyclopentane 3 2,3-dimethylpentane H3CCHCH3 j) CH3 h) H3C CH3 i) H C CH 3 CH 3 CH H CCHCH CH CH 2 3 2 3 methylpropane H2C CH2 methylbutane H C CH 2 2 CH3 methylcyclopropane m) CH H2C CH2 k) l) 2 CH H3CCH2CH2CH2CH H CCH CH CH CH CH H CCH 3 3 2 2 2 2 3 3 2 CH CH2 CH2CH3 pentane hexane 3-ethylhexane H2CCH2CH3 Chapter 21: Organic and Biochemical Molecules Chapter 21: Organic and Biochemical Big Idea: The large number of hydrocarbons arise Molecules from the ability of carbon atoms to form • Simple Organic long chains and rings Molecules with one another. The • Isomers properties of • Functional Groups hydrocarbons are dominated by the • Organic Reactions functional groups • Polymers present. Functional • Biochemistry groups properties are independent of their bonding environment. 2 Simple Organic Molecules Structural Representations Lewis Structure H H H H H H H C C C C C C H H H H H H H Chemical Formula CH3CH2CH2CH2CH2CH3 Line notation 3 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Structural Representations Lewis Structure Line Notation O Note: When other groups of Chemical Formula hydrocarbons are coming off of a longer chain of carbons CH2CHC(CH3)2CH2OCH3 they are put in parentheses in the chemical formula. 4 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Short Space Long Chemical Chemical Name Filling Short Hand Formula Formula Model H CH4 CH4 Methane C H H H C2H6 CH3CH3 Ethane C3H8 CH3CH2CH3 Propane C4H10 CH3CH2CH2CH3 Butane C5H12 CH3CH2CH2CH2CH3 Pentane 5 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Short Space Chemical Long Chemical Formula Name Filling Short Hand Formula Model CH CH CH CH CH CH C6H14 3 2 2 2 2 3 Hexane CH3CH2CH2CH2CH2CH2CH3 C7H16 Heptane CH CH CH CH CH CH CH CH C8H18 3 2 2 2 2 2 2 3 Octane CH CH CH CH CH CH CH CH CH C9H20 3 2 2 2 2 2 2 2 3 Nonane CH CH CH CH CH CH CH CH CH CH C10H22 3 2 2 2 2 2 2 2 2 3 Decane 6 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Branching Alkanes (CnH2n+2) 1. The longest continuous chain of carbon Example: atoms determines the root name for the hydrocarbon. Note the longest chain might not be in a straight line. 2. The longest chain will be named by Example: taking the core name and adding -ane. # of Carbons Core Name # of Carbons CoreName 1 meth- 6 hex- root name: hexane 2 eth- 7 hept- 3 prop- 8 oct- 4 but- 9 nan- 5 pent- 10 dec- 7 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Branching Alkanes (CnH2n+2) 3. When alkane groups Example: appears as a CH3CH2- ethyl substituent (bonded to a larger alkane), they are named by taking the core name and adding –yl. 4. When halogens are Halogen Name present as substituents F fluoro they are named using Cl chloro the following: Br bromo I iodo 8 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Branching Alkanes (CnH2n+2) 5. When multiple of the same Example: substituents are present the trimethyl appropriate prefix is added to the name of the substituent. # of the same Name substituents 2 di- 3 tri- 4 tetra- 9 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Branching Alkanes (CnH2n+2) 6. Number the carbons in Example: the chain so that the Correct Incorrect lowest number is given 1 3 4 2 2 4 3 1 to the substituent. 7. If both directions give Example: the same lowest number for the 1st Correct Incorrect 1 5 substituent then use the 3 5 3 1 numbering which gives 2 4 4 2 the lowest number for 2,2,4 2,4,4 the 2nd substituent. 10 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Branching Alkanes (CnH2n+2) 8. If two numbering schemes have the same lowest Example: numbering scheme, give the Correct Incorrect lowest number to the 3 4 substituent that appears first in 5 1 2 6 6 4 2 1 3 5 the name. Cl Cl 9. In front of each substituent, list the carbon number in which the substituent is bonds to in the Example: alkane. If there are multiple of 2,2,4-trimethyl one type of substituent, multiple numbers will need to be used. 4 2 Separate multiple numbers with 1 5 3 comas. Separate the number 6 from the name with a hyphen. 11 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Branching Alkanes (CnH2n+2) 10. Substituents are listed in alphabetic order with respect to their root name (methyl, ethyl etc.). If multiple substituents are present, they are separated from each other with a hyphen. The substituent that is closest to the root name is combined with the root name. Example: 4-ethyl-2,3-dimethyloctane 12 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules isopropyl CH3CHCH3 R H ―CH2―C―CH3 R isobutyl CH3 CH3CHCH2CH3 sec-butyl R CH3 ―C―CH3 R tert-butyl CH3 13 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Student Question Which of the following has the lowest boiling point? a) Butane b) Ethane c) Propane d) Methane 14 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Alkene and Alkynes 1. If a double bond is present, Example: the root hydrocarbon is the pentene longest chain that contains the double bond. The root hydrocarbon will be named by adding –ene to the core. 2. If a triple bond is present, the root hydrocarbon is the Example: longest chain that contains butyne the triple bond. The root hydrocarbon will be named by adding –yne to the core. 15 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Alkene and Alkynes 3. If multiple double and triple bonds are present Example: heptadiene the following notation is placed in front of the –ene # of bonds Name or –yne suffix which 2 di- identifies the number of 3 tri- bonds in addition an “a” is added to the root name. 4 tetra- 4. The root chain will be Example: numbered so that multiple Correct bonds get the lowest 2 4 6 8 possible number. This takes 1 3 5 7 precedence over giving Incorrect branching hydrocarbons or 7 5 3 1 8 2 halogens. 6 4 16 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Alkene and Alkynes Example: 5. Bonds are numbered in the C Numbers Bond Numbers same order as the carbons. 1 3 5 7 2 4 6 6. The bond number is placed in Example: front of the root name. If there root name: 3-octene are multiple double or triple bonds, multiple numbers will need to be used. Separate multiple numbers with comas. Separate the number from the name with a hyphen. 2 4 6 8 1 3 5 7 7. Usethe rules for naming Example: alkanes to name the rest of 7-methyl-3-octene the substituents. 17 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Cyclic Hydrocarbons 1. Use a ring for the root name if the ring has more carbons than any of the other chains. 2. The root name is formed by adding the prefix cyclo- to the core name (indicating the number of carbons). 3. If only single bonds exist in the ring, the suffix –ane is added to the core name. 4. If double bonds exist in the ring, the suffix –ene is added to the core name. If multiple double bonds exist, include di-, -tri-, etc. 5. Number the cyclic hydrocarbon so that double bonds get preference over halogen or hydrocarbon chains 2 3 Examples: 2 4 3 1 4 1 5 18 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Rules for Naming Cyclic Hydrocarbons 6. Include the number indicating the substituents placement in front of the name of the substituent. If there is only one double bond then the number 1 does not need to be included prior to the core name because the position of the double bond is implied. If there is only 1 substituent and no double bonds, the number does not need to be included because it is implied. Examples: Br 3-methylcylopentene 2-methyl-1,3-cylopentadiene bromocylopropane 7. Use rules for naming alkanes to complete the name of the structure. Example: 1-ethyl-2-methylcylobutane 19 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Shapes of Cyclic Hydrocarbons Carbon atoms in cycloalkanes are sp3 hybridized therefore the ideal C-C bond angle is 109.5˚. Cyclopropane Cyclobutane Cyclopentane Bond Angle: ~60˚ Bond Angle: ~90˚ Bond Angle: 108˚ Cyclohexane Flat Bond Angle: 120˚ Bent Bond Angle: ~109.5˚ 20 Chapter 21: Organic and Biochemical Molecules Simple Organic Molecules Aromatics: A compound that includes a benzene ring as part of its structure benzene toluene Note: Instead of showing the resonance structures for benzene, the symbol is used to represent benzene.