bruicech3 - Organic Chemistry I Chapter 3: Alkenes /...

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Organic Chemistry I Lecture Outline Chapter 3: Alkenes / Chapter 6: Alkynes Bruice, 5th edition I. DEFINITION & STRUCTURE OF ALKENES (Section 3.3) A. Alkenes (also called olefins or unsaturated hydrocarbons) are hydrocarbons that contain a C=C. B. The two carbon atoms which make up the carbon-carbon double bond are sp 2 hybridized. C. More highly substituted alkenes are more stable than less substituted alkenes. D. Trans alkenes are more stable than cis alkenes. C X Z C W Y W, X, Y, Z = substitutents on C 1 or C 2 1 2 Alkene Type C 1 Substitution C 2 Substitution Unsubstituted Two H atoms Two H atoms Monosubstituted (two possibilities) One H atom, one other than H Two hydrogen atoms Two H atoms One H; one other than H Disubstituted (three possibilities) Two H atoms Two other than H Two other than H atoms Two H atoms One H, one other than H One H, one other than H Trisubstituted (two possiblities) Two other than H One H, one other than H One H, one other than H Two other than H Tetrasubstituted Two other than H Two other than H II. NOMENCLATURE OF ALKENES (IUPAC) (Section 3.2) A. The suffix "ene" is used for alkenes. B. Name the parent by finding the longest, continuous carbon chain that contains the alkene functional group. Name according to the number of carbon atoms in that chain. C. Number the parent chain so as to give the lowest possible numbers to the carbon atoms of the double bond, then the lowest possible numbers to any substituents. D. If there is more than one double bond in the molecule the following suffixes are used in place of "ene": 1. Two double bonds: "diene" 2. Three double bonds: "triene" 3. Four double bonds: "tetraene" E. Only the lower number of one of the alkene carbons is used to indicate the alkene position in the name. F. CYCLOALKENES 1. Cycloalkenes are named just as cycloalkanes except the "ene" suffixes used in place of "ane". 2. For substituted cycloalkenes or for cycloalkenes that contain more than one double bond, the ring must be numbered to indicate the position of the double bond(s) relative to the substituent(s). G. ALKENES AS SUBSTITUENTS 1. When an alkene is a substituent on a larger molecule the "e"is dropped and replaced by a "yl" suffix. 2. There are some common names for alkenyl substituents. a. Two carbon: vinyl b. Three carbon: allyl
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Organic Chemistry I Lecture Outline Chapter 3: Alkenes / Chapter 6: Alkynes Bruice, 5th edition III. STEREOCHEMISTRY OF ALKENES (Section 3.4-3.6) A. DEFINITIONS 1. A "cis" stereoisomer (also called a Z isomer) is one in which the substituents of highest priority are on the same side of the double bond. 2. A "trans" stereoisomer (also called an E isomer) is one in which the substituents of highest priority are on opposite sides of the double bond. 3. PRIORITY RULES: Priority (or sequence) rules are used to assign order of priority to substituents.
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bruicech3 - Organic Chemistry I Chapter 3: Alkenes /...

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