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Handout: Hydrocarbons: IUPAC names

Naming Hydrocarbons (nomenclature). Handout: Hydrocarbons: IUPAC names. Drawing structures: it’s all good. 2-butene. On a test, choose a method that shows all Hs. This is called the “condensed structure”. CH 3 CH=CHCH 3.

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Handout: Hydrocarbons: IUPAC names

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  1. Naming Hydrocarbons(nomenclature) Handout: Hydrocarbons: IUPAC names

  2. Drawing structures: it’s all good 2-butene On a test, choose a method that shows all Hs This is called the “condensed structure” CH3CH=CHCH3 Using brackets can also shorten some formulas: CH3(CH2)4CH3 vs. CH3CH2CH2CH2CH2CH3

  3. Background: formulas for HCs • Alkanes= CnH2n+2, enes= CnH2n, ynes= CnH2n-2 • Remember enes, then think of what would happen if bond was single or triple instead. • Provides some useful information (e.g. for compositional analysis, or to check work) • Cannot always tell hydrocarbon type based on numbers (e.g. propyne vs. propadiene) Q - how many hydrogens in each of these: 6 carbon alkane Alkene: C22H 14 44 8 (2x5 - 2 = 10 - 2)

  4. Formic acid Acetone Acetylene Naming: common vs. IUPAC • Common names used in the 1800’s are still used for some compounds today: • The International Union of Pure and Applied Chemistry (IUPAC) was established in 1900s • Frequent revisions to nomenclature • Systematic method allows an infinite number of compounds to be named given a few rules

  5. Basic names of hydrocarbons • Hydrocarbon names are based on: 1) class 2) # of C, 3) side chain type and 4) position • 1) name will end in -ane, -ene, or -yne • 2) the number of carbons is given by a “Prefix” 1 meth- 2 eth- 3 prop- 4 but- 5 pent- 6 hex- 7 hept- 8 oct- 9 non- 10 dec- • Actually, all end in a, but a is dropped when next to a vowel. E.g. a 6 C alkene is hexene Q - What names would be given to these: 7C, 9C alkane 2C, 4C alkyne 1C, 3C alkene heptane, nonane ethyne, butyne does not exist, propene

  6. Monkeys Eat Peeled Bananas Mnemonic for first four prefixes First four prefixes • Meth- • Eth- • Prop- • But-

  7. Other prefixes • Pent- ? Decade Decimal Decathalon • Oct- • Dec- • Hex-, Hept-, Non-

  8. C2H4 Numbering carbons 1-pentene Q- draw pentene A- Where’s the bond? We number C atoms • Thus, naming compounds with multiple bonds is more complex than previously indicated • Only if 2+ possibilities exist, are #s needed • Always give double bond the lowest number • Q - Name these 2-butene Ethene 3-nonyne

  9. CH3CH2CH2CH=C=CH2 Multiple multiple bonds 2,3-heptadiene 2,4,6-nonatriyne • Give 1st bond (1st point of difference) lowest # • include di, tri, tetra, penta, etc. before ene/yne • Comma between #s, hyphen between #-letter • You do not need to know ene + yne 2-butyne 1,2,4-pentatriene 1,2-hexadiene

  10. Cyclic structures • Cyclic structures are circular • Have “cyclo” in name • Benzene is not a cyclic structure • cyclopentane Q- Draw these (note: carbons in a double bond should be consecutive- 1 and 2, 5 and 6, etc.): cyclobutene 1,3-cyclopentadiene cyclopropane

  11. C H 3 H C C H 3 3 C H 3 Naming side chains • 2,3-dimethylpentane • Names are made up of: side chains, root • Root is the longest possible HC chain • Must contain multiple bonds if present • Add -yl to get name of side chain • Common side chains include: CH3- methyl CH3CH2- ethyl CH3CH2CH2- propyl (CH3)2CH- isopropyl • “iso” (branched) is not an IUPAC convention • Br- (bromo), Cl- (chloro), F- (fluoro), I- (iodo)

  12. Naming side chains Example: use the rules on the bottom of handout to name the following structure Rule 1: choose the correct ending ene

  13. Naming side chains Rule 2: longest carbon chain ene

  14. Naming side chains Rule 3: attach prefix (according to # of C) 1-hexene ene

  15. Naming side chains Rule 4: Assign numbers to each carbon 1-hexene

  16. Naming side chains Rule 4: Assign numbers to each carbon 1-hexene 1-hexene

  17. Naming side chains ethyl methyl methyl Rule 5: Determine name for side chains 1-hexene 1-hexene

  18. Naming side chains ethyl methyl methyl Rule 6: attach name of branches 2-ethyl-4-methyl-4-methyl-1-hexene 1-hexene

  19. Naming side chains ethyl methyl methyl Rule 7: list alphabetically 2-ethyl-4-methyl-4-methyl-1-hexene 1-hexene

  20. Naming side chains ethyl methyl methyl Rule 8,9: group similar branches 2-ethyl-4-methyl-4-methyl-1-hexene 1-hexene

  21. Naming side chains ethyl methyl methyl Rule 8,9: group similar branches 2-ethyl-4,4-dimethyl-1-hexene

  22. Naming side chains • Try PE 1 on pg. 1019 (answer to a is wrong) 3-methylhexane 4-ethyl-2,3-dimethylheptane 5-ethyl-2,4,6-trimethyloctane

  23. Naming side chains Name the structures below 3-ethyl-2-methylpentane 3-ethyl-1,5,5-trimethylcyclohexene

  24. More practice Pg. 1049 # 24.5, 24.6, 24.7, 24.14, 24.15 Ignore 24.15 e) 4-bromo-7-methyl-2-nonene 2,5-dibromo-6-chloro-1,3-cycloheptadiene 5-fluoro-7,7-dimethyl-2,4-octadiene

  25. Pg. 1049 24.5 - Recall, the exceptions to organic compounds are oxides of carbon, carbonates, bicarbonates, cyanides. b) is an oxide, d) bicarbonate, e) carbonate 24.6 - This is a straight chain molecule as all carbons are consecutive. 24.7 - none are possible: a) one too few Hs (should be CH3CH2CH3), b) one H too many (should be CH2=CHCH2CH3), c) one H too many (should be CH3CH=CHCH2CH3).

  26. 24.15 2,2-dimethyloctane 1,3-dimethylcyclopentane 1,1-diethylcyclohexane 6-ethyl-5-isopropyl-7-methyl-1-octene

  27. Ortho Meta Para Aromatic nomenclature 1,2-dimethylbenzene orthodimethylbenzene There are 2 naming methods • Numbering carbons • ortho, meta, para (stomp) ST 1,3-dimethylbenzene metadimethylbenzene Benzene is very stable (does not generally undergo addition) 1,4-dimethylbenzene paradimethylbenzene

  28. More practice • Build a molecule that can be named according to the rules that we have talked about. Make it challenging. • Place your model at a vacant lab station. • On a scrap piece of paper write the following: 1) your station number, 2) the structure of your molecule, 3) the name of the structure. Give this to your teacher. • Rotate through the stations, drawing the structures and determining their names. At the end of the class students will reveal the answer with an explanation. For more lessons, visit www.chalkbored.com

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