Organic Chemistry Nomenclature PDF

# Drawing Alkanes - **Methane** - H - H - C - H - HICIH - **Ethane** - H-C-H - CH3 - HH - H-C-C-H - HH - CH3CH3 - **Propane** - HH - HHH - H-C-C-C-H - HHHH - HHH CH3CH2CH3 - **butane** - HHHH - H-C-C-C-C-H - нннн CH3CH2CH2CH3 - **n-Pentane**...

# Drawing Alkanes - **Methane** - H - H - C - H - HICIH - **Ethane** - H-C-H - CH3 - HH - H-C-C-H - HH - CH3CH3 - **Propane** - HH - HHH - H-C-C-C-H - HHHH - HHH CH3CH2CH3 - **butane** - HHHH - H-C-C-C-C-H - нннн CH3CH2CH2CH3 - **n-Pentane** - H - H - H - H - CH3CH2CH2CH2CH3 - H - H - H - H - H - H - H - CH3(CH2)3CH3 # Branched Hydrocarbons: ## Naming Side Chains 1. Identify the parent chain: the longest possible HC chain 2. Identify substituents (side chains or groups) ### Common side chains include: #### Alkyl groups (add -yl to prefix) - CH3 - methyl - CH3CH2 - ethyl - CH3CH2CH2 - propyl - (CH3)2CH - isopropyl #### Halide groups - Br - (bromo) - Cl - (chloro) - F - (fluoro) - I - (iodo) # Representation of Molecular Formulae - Ball and stick model - HHH - H----о-н - ΗΗΗ - dash(Structural) formula - CH3CH2CH2OH - Condensed formula - OH - Bond Line(Skeletal) formula # Naming Substituted Cycloalkanes - Count the number of carbon atoms in the ring and the number in the largest substituent chain. If the number of carbon atoms in the ring is equal to or greater than the number in the substituent, the compound is named as an alkyl-substituted cycloalkane i.e. use the prefix cyclo followed by the suffix indicate the number of carbon atoms. - For an alkyl- or halo-substituted cycloalkane, start at a point of attachment as C and number the substituents on the ring so that the second substituent has as low a number as possible. - Number the substituents and write the name with the substituents in alphabetical order. ## Examples - tert-butylcycloheptane - 1-cyclobutyl-4-methylpentane # Practice: Name this molecule - parent chain: nine carbons - two methyl groups - one ethyl group # Example: Cycloalkane as a substituent - Treat cycloalkane as a substituent group if it is attached to a parent chain that has more carbons. - This compound is: 6-methyl-3-cyclopropyldecane # There is a -CH3 group attached to the octane chain: It is a methyl group - CH3 - CH3-CH2-CH2-CH2-CH2-CH-CH2-CH3 - The parent chain contains 8 carbons: It is octane # Common Names - Isopentane - Neopentane - n- Pentane - **CH2Cl2** - Common: Methylene chloride - IUPAC: Dichloromethane - **CHCI3** - Chloroform - Trichloromethane - **CCI4** - Carbontetrachloride - Tetrachloromthane # Cis-Trans Isomerism in Cycloalkanes - Rotation about C-C bonds in cycloalkanes is limited by the ring structure. - There are two different 1,2-dimethylcyclopropane isomers, one with the two methyl groups on the same side **(cis)** of the ring and one with the methyls on opposite sides **(trans)**. ## Examples - cis-1,2-Dimethylcyclopropane - trans-1,2-Dimethylcyclopropane # If there are different groups attached: - list them alphabetically in the name ## Examples - CH3 CH3 - methyl - group - (C2) - CH3 - CH2 CH2 CH3 - CH3- CH2 – CH2 - CH - CH - CH - CH3 - This compound is: 3,4-diethyl-2-methylheptane # Important Notes - The common names isopropyl, isobutyl, sec-butyl, tert-butyl are approved by the IUPAC for the substituted groups. - Substituent groups are cited in the name in alphabetical order, regardless of their order of occurrence in the molecule. Multiplication prefixes di, tri, ect. and structural prefixes sec., tert. (written in italics and separated from the name by a hyphen) are ignored, but prefixes iso and cyclo are not! - Thus "tert-butyl" precedes "ethyl", but ethyl preceeds "isopropyl" - 3-ethyl comes before 2,2-dimethyl - 4-hexyl comes before 2,3-diisopropyl - 3-Tert-butyl comes before 3-isopropyl ## Examples - 6-tert-Butyl-2-methyl-decane - 4-Isopropyl-3-methyl-decane # Practice: Name this molecule - parent chain: nine carbons - two methyl groups - one ethyl group # Example: Cycloalkane with single substituent - Br - This compound is: bromocyclopentane - Notice a number is not required when there is only one substituent group # Naming Rules - di = 2, tri=3, tetra=4 - number all carbons on the parent chain where groups are attached - separated by commas ## Examples - CH3 - CH3-CH-CH-CH2-CH2-CH2-CH2-CH3 - This compound is: 2,3-dimethyloctane # Example: Cycloalkane with multiple substituents - Start numbering C1 with lowest alpha substituent (ethyl >> methyl) ## Examples - CH3 - 1-ethyl-3-methylcyclohexane - CH3 - 1-ethyl-5-methylcyclohexane # Practice: Name these molecules ## (A.) - 4H3C-CH2 - H2C-CH2 - CH-CH3 - CH-CH-CH2-CH3 - CH3 ## (B.) - H3C - CH2-CH2-CH3 - CH-CH3 - CH-CH-CH2-CH3 - CH3 ## (C.) - CH3 - CH3 - CH3CH2CH-CH-CH-CH2CH-CH3 - CH2CH3 - CH-CH₃ # Practice: Draw the structures below - 3-ethyl-2-methylpentane - 3-ethyl-1,5,5-trimethylcyclohexene # Geometric Isomers in cycloalkanes and alkenes - A cis isomer is one in which the substituents are on the same side of the C=C or cyclic alkane - A trans isomer is one in which the substituents are on the opposite sides of the C=C or cyclic alkane ## Examples - cis-1,2-dichlorocyclopropane - trans-1,2-dichlorocyclopropane