University:
Texas State University
Course:
CHEM 1320 | Foundations of Chemistry
Academic year:

2023
Views:

35

Pages:

12
Author:

gewoekerdodx

Alkene - Alkyne Chapter 11: Introductio to bonding Unsaturated hydrocarbons with double bond alkene -> C=C double bond ethene Simplest hydrocarbon with C=C that contains term is C=C General molecular formula : CnH2n Elements of unsaturation - no. of pi-bonds + no. of rings / formula (degree of unsaturation / index of hydrogen deficiency) CH3 - CH2 - CH3 Only C and H Elements of unsaturation = (2C + 2 + N) / 2 DOU = (2(4) + 2 + 0 - 8) / 2 DOU = (8+2-8)/2 DOU = 2/2 = 1 For C4H8: DOU = 2(4) + 2 - 8 = 2 DOU = 2/2 = 1 Elements of unsaturation with hetero atoms Halogens - treat halogens as if they are H atoms Oxygen - ignore oxygen atoms Nitrogen - For each nitrogen atom, add 1 H atom n = # carbons x = # halogens n = # nitrogen x = # oxygen DOU = (2C + 2 + N - X) / 2 Alkene Nomenclature Identify the parent chain, includes C=C double bond. Identify and name substituents. Assign a locant (use prefix if necessary) to each substituent. Give C=C double bond smallest possible List the numbered substituents before parent name in alphabetical order. When prefixes (except iso) begin naming alphabetically. 3, 3, 5 - trimethyl - 2 - heptene C=C double bond locant is placed either just before parent name or before the -ene suffix. E and Z configuration Z - Zame priority groups are on the Zame Side of the double bond. Z = higher atomic # E - Eposite priority groups are on Eposite Sides of the double bond. Cis - Trans Isomers Cis: Similar groups on same side of double bond Trans: Similar groups on opposite sides of double bond Both of cis & trans, all isomers are generally full double bond Multiple Double Bonds Give the double bond the lowest numbers possible The cis, trans or Z/E - before the number - ene to specify # of double bonds present Ring Nomenclature In a ring, double bond is assumed to be between C1 and C2 Alkene Stability Increasing stability More substituted -> more stable Mono-substituted Di-substituted Tri-substituted Tetra-substituted Alkene Reactions Addition Reactions The pi bond is an electron pair donor at a pi bond As a nucleophile Alkenes -> nucleophilic and can attack electrophiles (primarily) (primarily) Alkenes double bonds Formula: CnH2n A + B -> A - B Examples: HBr OH H2O, H+ What is the product? What is the product? Reactions of Alkenes Addition of HX Electrophilic addition of H-X Acid-catalyzed addition of H2O Hydroboration - oxidation Peroxide addition - anti-Markovnikov Reactions of X2 (halogens) syn Hydroxylation / anti Ozonolysis Questions to ask for alkene rxns: What are we adding across the double bond? Which side one group goes on Markovnikov / anti-Markovnikov? What is the expected stereo- chemistry of the added groups?

Understanding Organic Chemical Structure and Bonding Part 1

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