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Handout: Hydrocarbons: IUPAC names Naming Hydrocarbons (nomenclature)

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Presentation on theme: "Handout: Hydrocarbons: IUPAC names Naming Hydrocarbons (nomenclature)"— Presentation transcript:

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2 Handout: Hydrocarbons: IUPAC names Naming Hydrocarbons (nomenclature)

3 Drawing structures: its all good 2-butene This is called the condensed structure On a test, choose a method that shows all Hs CH 3 CH=CHCH 3 Using brackets can also shorten some formulas: CH 3 (CH 2 ) 4 CH 3 vs. CH 3 CH 2 CH 2 CH 2 CH 2 CH 3

4 Background: formulas for HCs Alkanes= C n H 2n+2, enes= C n H 2n, ynes= C n H 2n-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: C 22 H (2x5 - 2 = )

5 Naming: common vs. IUPAC Common names used in the 1800s are still used for some compounds today: Acetylene AcetoneFormic acid 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

6 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

7 Mnemonic for first four prefixes First four prefixes Meth- Eth- Prop- But- Monkeys Eat Peeled Bananas

8 ? Decade Decimal Decathalon Other prefixes Pent- Oct- Dec- Hex-, Hept-, Non-

9 Numbering carbons Q- draw pentene A- Wheres 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 Ethene 3-nonyne 2-butene C2H4C2H4 1-pentene

10 Multiple multiple bonds Give 1 st bond (1 st 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 2,3-heptadiene 2,4,6-nonatriyne CH 3 CH 2 CH 2 CH=C=CH 2 2-butyne 1,2-hexadiene 1,2,4-pentatriene

11 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

12 Naming side chains 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: CH 3 - methyl CH 3 CH 2 - ethyl CH 3 CH 2 CH 2 - propyl (CH 3 ) 2 CH- isopropyl 2,3-dimethylpentane CH 3 CH 3 CH 3 CH 3 iso (branched) is not an IUPAC convention Br- (bromo), Cl- (chloro), F- (fluoro), I- (iodo)

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

14 ene Rule 2: longest carbon chain Naming side chains

15 1-hexene ene Rule 3: attach prefix (according to # of C) Naming side chains

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

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

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

19 1-hexene2-ethyl-4-methyl-4-methyl-1-hexene Naming side chains ethyl methyl Rule 6: attach name of branches

20 Rule 7: list alphabetically 1-hexene2-ethyl-4-methyl-4-methyl-1-hexene Naming side chains ethyl methyl

21 Rule 8,9: group similar branches 1-hexene2-ethyl-4-methyl-4-methyl-1-hexene Naming side chains ethyl methyl

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

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

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

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

26 Pg Recall, the exceptions to organic compounds are oxides of carbon, carbonates, bicarbonates, cyanides. b) is an oxide, d) bicarbonate, e) carbonate This is a straight chain molecule as all carbons are consecutive none are possible: a) one too few Hs (should be CH 3 CH 2 CH 3 ), b) one H too many (should be CH 2 =CHCH 2 CH 3 ), c) one H too many (should be CH 3 CH=CHCH 2 CH 3 ).

27 ,2-dimethyloctane 1,3-dimethylcyclopentane 1,1-diethylcyclohexane 6-ethyl-5-isopropyl-7-methyl-1-octene

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

29 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


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