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Organic Nomenclature

Organic Nomenclature. Compounds in which carbon is the principal element. Writing formulas. Condensed: CH 3 CH(CH 3 )CH = CHCH(CH 3 )CH 3 Kekule’ Skeletal. Hydrocarbons. Contain only hydrogen and carbon. Types:

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Organic Nomenclature

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  1. Organic Nomenclature Compounds in which carbon is the principal element.

  2. Writing formulas. . . Condensed: CH3CH(CH3)CH = CHCH(CH3)CH3 Kekule’ Skeletal

  3. Hydrocarbons. . . Contain only hydrogen and carbon. Types: Alkane: single bonds; saturated (largest possible number of hydrogens/carbon atom. [CnH2n+2] Alkene: one or more carbon-carbon double bond. Unsaturated hydrocarbon. Alkyne: one carbon-carbon triple bond. Unsaturated hydrocarbon. Aromatic: carbon atoms connected in a planar ring. Unsaturated hydrocarbon.

  4. Hydrocarbons. . . Relatively nonpolar. (covalent bonds) Insoluble in water. (like dissolves like) Less volatile with increasing molar mass. (because of London dispersion forces)

  5. Alkanes. . . [CnH2n+2] Methane: CH4 major component of natural gas; home heating; gas stoves; hot water heaters Ethane: C2H6 Propane: C3H8 used for home cooking and heating; gas grills Butane: C4H10 disposable lighters and fuel canisters for gas camping stoves.

  6. Name consists of. . . 1. Prefix Where are the substituents? 2.Parent How many carbons in the longest chain? 3. Suffix Which family? If two different chains of equal length are present: choose the one with the larger number of branch points as the parent.

  7. Rules for naming alkanes. . . Longest continuous chain of carbon atoms gives the root name 1. For alkanes, add –ane to the root: Meth: C Eth: C2 Prop: C3 But: C4 2. For alkanes beyond butane, use the Greek root for the number of carbons then add -ane to the end. C-C-C-C-C-C = hexane pent=5; hex=6; hept=7; oct=8; non=9; dec= 10

  8. Substituent Group(s) added in place of a removed hydrogen.

  9. Alkanes as a substituent group. . . Alkyl substituents: 1. Remove a hydrogen from the alkane. C2H6 is ethane 2. Drop the -ane and add -yl. -C2H5 is ethyl

  10. Positions of substituent groups are specified by numbering the longest chain sequentially. (Use the lowest number for the position of the substituent group) The location and name of the substituent group is followed by root alkane name. • C • C-C-C-C-C-C 3-methylhexane

  11. Substituents in alphabetical order. Use di-, tri-, etc. to indicate multiple identical substituents.

  12. Practice. . .write skeletal and condensed formulas. 2,3-dimethylhexane 2-ethyl-3-methylpentane 4-ethyl-3,5-dimethylnonane 4-tert-butylheptane 2,3-dimethylpentane

  13. Cyclic Alkanes. . . CnH2n Cycloalkanes Smaller than five carbons, very reactive. Rings of carbon atoms. Isomers Cis: both substituents are on the same side of the ring. Trans: substituents are on opposite sides of the ring.

  14. Reactions of Alkanes. . . . Combustion: react with oxygen produce carbon dioxide and water Substitution: halogen atoms replace hydrogen atoms Dehydrogenation reactions:hydrogen removed forms double bond there unsaturated hydrocarbon is the product

  15. Alkenes. . . 1. Root hydrocarbon (longest chain containing double bond) name ends in –ene. 2. More than three carbon atoms, the location of the double bond is indicated by the lowest numbered carbon atom in the bond. If equidistant: begin at end closer to substituent group. CH2=CHCH2CH3 1-butene CH3CH=CHCH3 2- butene 3. More than one double bond Indicate the position of each and use –diene, triene, tetraene. . .

  16. Cycloalkenes. . . Name same as alkenes. Number so double bond is between C1 and C2 and the first substituent has the lowest number possible.

  17. Practice. . .write the skeletal formula and name. CH2=CHCH(CH3)C(CH3)(CH3)CH3 CH3CH2CH=C(CH3)CH2CH3 CH3CH=CHCH(CH3)CH=CHCH(CH3)CH3

  18. Practice. . . 2-methyl-1,5-hexadiene 3-ethyl-2,2dimethyl-3-heptene 2,3,3-trimethyl-1,4,6-octatriene 4-tert-butyl-2-methylheptane 3,4-diisopropyl-2,5-dimethyl-3-hexene

  19. Practice. . . CH3 CH3 CH(CH3)2 CH3 CH3

  20. Alkynes. . . Unsaturated hydrocarbons contain atleast one triple carbon-carbon bond. -yne replaces –ane. Begin numbering chain at end closest to triple bond. More than one bond: -diynes, -triynes. Double and triple bonds: -enynes Start numbering from end nearer first bond. (if there is a choice. Usually double bonds get lower numbers than triple.)

  21. Practice. . . CH3CH(CH3)C CCH(CH3)CH3 CH CC(CH3)(CH3)CH3 CH3CH=CHCH=CHC CCH3 CH3CH2C(CH3)(CH3)C CCH2CH2CH3

  22. Practice. . .

  23. Reactions of Alkenes and Alkynes. . . Addition reactions: double bond broken and new bonds formed to atoms added. Hydrogenation reactions: addition of hydrogen atoms Halogenation: addition of a halogen Elimination:one reactant splits apart to give two products. Substitutions: two reactants exchange parts to give two new products. Rearrangement:one reactant undergoes a reorganization of bonds and atoms to give a new product.

  24. Aromatic Hydrocarbons. . .Benzene and its structural relatives Monosubstituted benzene: named as other hydrocarbons, with benzene as parent name. If substituent larger than ring (six carbons) : benzene becomes substituent group called phenyl. Disubstituted benzene: ortho:1,2 meta-1,3 para-1,4 More than two: number the position of each substituent group.

  25. Alcohols. . . Alcohols: presence of an –OH (hydroxyl group) Nomenclature: replace final -e of parent hydrocarbon with –ol. (parent: longest chain containing –OH) Position of –OH specified by number- lowest number. Classified by: number of hydrocarbon fragments bonded to carbon where –OH group is attached. eg. C-C-C-C or C-C-C-C or C C-C-C

  26. Functional Groups

  27. Alcohols. . . . Polar Higher boiling points than expected from molecular weights. Intermolecular attractions. –OH extensive hydrogen bonding.

  28. Practice. . . CH3C(OH)(CH3)CH2CH2CH3 2methyl-2-pentanol CH3CH(OH)CH2CH(OH)CH(CH3)2 5-methyl-2,4-hexanediol

  29. Practice. . .

  30. Practice. . . 2-ethyl-2-buten-1-ol 3-cyclohexen-1-ol 3-chlorocycloheptanol 1,4-pentanediol

  31. Aldehydes. . . Nomenclature: remove –e replace with –al. Longest chain as base name,must contain the carbonyl group. Aldehyde carbon assigned number 1, when subtituent positions are listed in the name. Bonded to at least one hydrogen atom. Number indicates position of carbonyl group.

  32. Practice. . .

  33. Practice. . . CH3CHO Ethanal CH3CH2CHO Propanal CH3CH(CH3)CH2CH(CH2CH3)CHO 2-ethyl-4-methylpentanal

  34. Ketones. . . Contain carbonyl group bonded to two carbon atoms Final –e replaced with -one. Longest chain with ketone group is the parent. Numbering begins at the end nearest the carbonyl carbon.

  35. Practice. . . CH3CH=CHCH2COCH3 4-hexen-2-one CH3CH2COCH2COCH3 2,4-hexanedione CH3CH2COCH(CH3)2 2-methyl-3-pentanone CH3COCH2CH2CH2COCH2CH3 2,6-octanedione

  36. Practice. . . OHCCH2CH2CH2CHO Pentanedial CH3CH2CH(CH3)CH(CH2CH2CH3)COCH3 4-methyl-3propyl-2-hexanone CH3CH=CHCH2CH2CHO 4-hexenal

  37. Practice. . . 3-methylbutanal 3-methyl-3-butenal 4-chloro-2-pentanone

  38. Carboxylic Acids. . . Two systems: aldehyde and alcohol Derived from open chain alkanes: Carboxyl carbon is always C1. Replace terminal –e of alkane with –oic acid. -COOH group bonded to a ring, the suffix –carboxylic acid is used. The carboxylic acid carbon is attached to C1 and is not itself numbered in this system.

  39. Practice. . . CH3CH(CH3)CH2CH2COOH 4-methylpentanoic acid HOOCCH2CH(CH2CH3)CH2CH2CH(CH3)CH2COOH 3-ethyl-6-methyloctanedioic acid

  40. Practice. . .

  41. Practice. . . (CH3)2CHCH2COOH 3-methylbutanoic acid CH3CHBrCH2CH2COOH 4-bromopentanoic acid CH3CH=CHCH=CHCOOH 2,4-hexadienoic acid CH3CH2CH(COOH)CHCH2CH2CH3 2-ethylpentanoic acid

  42. Carboxylic Acids. . . Strong hydrogen bonding has a noticeable effects on boiling points. Much higher than corresponding alcohols.

  43. Isomerism

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