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I nternational U nion of P ure and A pplied C hemistry

IUPAC Nomenclature of Hydrocarbons. I nternational U nion of P ure and A pplied C hemistry. Models Used to Represent Structures. Naming Alkanes. The IUPAC name of any organic compound has three basic parts

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I nternational U nion of P ure and A pplied C hemistry

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  1. IUPAC Nomenclature of Hydrocarbons I nternational U nion of P ure and A pplied C hemistry

  2. Models Used to Represent Structures

  3. Naming Alkanes • The IUPAC name of any organic compound has three basic parts Root- denotes number of carbon atoms in the longest continuous chain of carbon atoms Prefix- gives positions and names of any branches Suffix- indicates series to which the molecule belongs (e.g. alkane, alkene alkyne)

  4. Root and Side Group Names of Alkanes

  5. The alkanes (CnH2n+2)

  6. Steps for Naming Alkanes • Longest chain has 6 carbon atoms • Root name is hex- • Compound is alkane • Suffix is -ane 1. Identify the root • Identify the longest continuous chain • Find the root name for the number of carbons in the chain 2. Identify the suffix

  7. Identify the prefix (name the branches) • Identify the number of carbon atoms in each branch • Determine the name of each branch • Number the C atoms on the longest chain to produce the lowest number combinations (or sum) for the branches • Two branches have one carbon atom and 3rd branch has 2 carbon atoms • Methyl- and ethyl-

  8. Precede the name of each branch with the number of the carbon atom to which it is attached on the main chain. • For more than one of the same branch use a prefix: di = 2 ,tri = 3, tetra = 4, penta = 5 • Separate numbers using commas • Separate numbers and words using hyphens • 3-ethyl • 2,4-dimethyl

  9. Arrange branches alphabetically (ignore prefixes di, tri, etc…) 4. Name the compound • Combine prefix, root, and suffix to name the compound • Prefix: 3-ethyl-2,4-dimethyl • Root: hex- • Suffix: -ane • Name: 3-ethyl-2,4-dimethylhexane

  10. Finding the longest continuous chain of carbon atoms is not always simple all possibilites must be examined C-C C-C-C-C-C-C-C-C-C it won’t always be the horizontal one as shown here C 9 try these also …….. C-C C-C C-C-C-C-C-C C-C-C- C-C-C C- -C-C-C-C-C C 6 8 C

  11. Name this alkane 4 3 2 1 2-methylbutane

  12. Find the longest continuouscarbon chain 1 2 3 4 5 3-methylpentane

  13. Name the Following Compound 4 3 2 1 5 6 7 4-ethylheptane

  14. Number from the end nearestthe first substituent 7 6 5 4 3 2 1 4-ethyl-3-methylheptane

  15. Number from the end nearestthe first substituent 8 7 6 5 4 3 2 1 3-ethyl-5-methyloctane

  16. Use “di-” with two substituents 1 2 3 4 2,3-dimethylbutane

  17. Every substituent must get a number 1 2 3 4 5 6 3,3-dimethylhexane

  18. You need numbers, even though it appears on the same carbon! 5 4 3 2 1 2,2,4-trimethylpentane

  19. Name the following compound 1 2 3 4 5 6 7 8 9 10 3,4,8-trimethyldecane

  20. Name the following compoundDimethyl alphabetized as methyl, not dimethyl 1 2 3 4 5 6 7 8 6-ethyl-3,4-dimethyloctane

  21. Drawing Alkanes e.g. draw 3-ethyl-3-methylpentane root: pent- suffix: -ane C-C-C-C-C 1 2 3 4 5 • Identify the root • Gives the number of carbon atoms in the main chain • Identify the suffix • Indicates the type of bond between carbon atoms 3. Draw and number main chain

  22. Identify the prefix and draw the side groups Complete the condensed structural formula Prefix: 3-ethyl-3-methyl- (ethyl and methyl group on carbon 3)

  23. Draw the structural diagram of 2-methylheptane

  24. Physical Properties of Alkanes • Since alkanes are non-polar, they are not soluble in water

  25. Naming Alkenes 1. Identify the root • Identify longest chain with a double bond. • Assign root name based on number of carbons • Identify the suffix • Number the main chain by starting at the end of the chain nearest the double bond. Root: pent- Suffix: -2-ene • (indicate the number of the carbon atom that precedes the double bond, only if alkene has 4 or more carbons)

  26. Root: pent- Prefix: 2,3-dimethyl- Suffix: -2-ene Name: 2,3-dimethylpent-2-ene • Identify the prefix • Name the side groups on alkenes as you would for alkanes • Name the compound. • Combine the prefix, root and suffix.

  27. ethene propene but-1-ene but-2-ene

  28. 2-methylbut-2-ene

  29. 6-methylhept-2-ene

  30. trans-6-methyl-3-propyloct-2-ene

  31. Drawing Alkenesdraw a structural formula for 2-methylbut-1-ene • Identify the root • Identify the suffix • Draw and number the main carbon chain • Identify the prefix and draw the branches • Complete the structural formula by adding hydrogens Root: but- (4 carbons) Suffix: double bond between c-1 and c-2 Prefix: methyl group on c-2

  32. Naming Alkynes 1. Identify the root • Identify longest chain with a triple bond. • Assign root name based on number of carbons • Identify the suffix • Number the main chain by starting at the end of the chain nearest the triple bond. Root: pent- Suffix: -1-yne • (indicate the number of the carbon atom that precedes the triple bond, only if alkyne has 4 or more carbons)

  33. Root: pent- Prefix: 3-methyl- Suffix: -1-yne Name:3-methylpent-1-yne • Identify the prefix • Name the side groups on alkynes as you would for alkanes • Name the compound. • Combine the prefix, root and suffix.

  34. Drawing Alkynesdraw a structural formula for 3-ethyhex-1-yne • Identify the root • Identify the suffix • Draw and number the main chain • Identify the prefix and draw any side groups • Add enough hydrogen atoms to give each carbon atom four bonds. • Root: hex- (6 carbons) • Suffix: -1-yne (triple bond between c1and c2 • Prefix: ethyl group on c3

  35. ethyne propyne “acetylene” but-1-yne but-2-yne

  36. ALKYNES ( -YNE ) The functional group has precedence in numbering. Hex-2-yne functional group The suffix has precedence over any branches 4-methylpent-2-yne

  37. nomenclature of halides and nitro compounds

  38. 4-chloro-4-methylpent-2-yne 5-bromo-2-methylhept-3-yne

  39. ene vs. yne: which one wins? Number from the end closest to either the double bond or the triple bond, whichever is closest to the end. Compounds are named: en-yne. 8 7 6 5 4 3 2 1 CH3-CH2-C C-CH2-CH=CH-CH3 oct-2-en-5-yne

  40. cycloalkanes • The names of the cycloalkanes always contain the prefix cyclo • Cycloalkanes have the general formula CnH2n

  41. Cyclic molecules

  42. Naming Cyclic Hydrocarbons 1. Identify the root • Determine number of carbon atoms in the ring. Assign root name • 2. Identify the suffix • Not necessary to indicate location of double or triple bonds, always between c1-c2 Root: pent- Suffix: -1-yne • (indicate the number of the carbon atom that precedes the triple bond, only if alkyne has 4 or more carbons)

  43. Naming Cyclic Hydrocarbons • 3. Identify the prefix. • If there is only one substituent, do not use the “1”. • If there is more than one substituent, you must use all numbers, including “1”! • If there are two or more side groups, the numbering must start with a side group and then proceed in the direction that gives the lowest possible numbers to all the side groups. • If numbers are the same for two or more side groups, the side group that comes first alphabetically is assigned as c-1.

  44. Naming Cyclic Hydrocarbons • If the molecule is a cyclic alkene or cyclic alkyne, the multiple bond takes highest priority. The carbon atom on one side of the multiple bonds is c-1 and one the other side is c-2. If there are side groups, the numbering starts in the position that will make the number of the carbon atoms bonded to the side groups as small as possible. • 4. Name the compound • Combine the prefix, root, and suffix to name the compound.

  45. Naming Cyclic Hydrocarbons • Root: cyclopent • Suffix:-ene • Prefix:3,4-dimethyl Name: 3,4-dimethylcyclopentene

  46. 1,1-dimethylcyclohexane

  47. 4-ethyl-1,1-dimethylcyclohexane

  48. C H 3 C H 3 C H 3 C H C H 3 3 C H 3 C H 3 C H C H 3 2 C H C H 2 3 Some cycloalkanes 1,3-dimethylcyclopentane Drawn differently but same name. 1 2 1 = 2 3 3 4 3 1 2 2 1 3 3-ethyl-1,1-dimethylcyclobutane 1-ethyl-4-methylcyclohexane The more substituted carbon takes precedence even though E comes before M. E before M

  49. Numbering starts at the most highly-substituted carbon 2 1 3 7 4 6 5 2-chloro-1,1,6-trimethylcycloheptane

  50. cycloalkyl groups

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