Agenda Today Lesson on Naming and Structure of: – Alkanes – Branched Alkanes – Cycloalkanes – Alkyl Halides Practice Problems

Unit 1: Organic Chemistry Chapter 1 Organic Compounds Chapter 2 Polymers

1.1 Alkanes Organic Compounds: a molecular compound of carbon (exceptions are carbides, oxides of carbon, and cyanides) Special Nature of Carbon: -Bonding capacity is 4 -Relatively small atom (atomic number is 6) -Has an intermediate value for Electronegativity -As a result, carbon atoms bond with another to form long chains (“carbon backbone”) that can become very complex -Carbon-based molecules are the building blocks for life on Earth

Hydrocarbon: compound composed only of carbon and hydrogen atoms Saturated hydrocarbon: a hydrocarbon with only single covalent bonds between its carbon atoms; an alkane - The simplest hydrocarbon is methane, CH 4

Physical Representations for Organic Compounds: 1)Structural formula 2)Ball-and-stick model 3)The space-filling model Figure 1: Three representations of ethane, C 3 H 6 : a) structural formula; b) ball-and-stick; and c) space- filling model

The prefix (i.e. meth-, eth-, prop-, etc.) indicates the number of carbons. The suffix, -ane, indicates single bonds. Chemical Formula C n H 2n+2 Refer to page 9 in text

How to Draw Organic Structures Example: Drawing heptane, C 7 H 16 1)Structural formula a)Expanded formula b)Condensed formula 2)Line diagram CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 CH 3 (CH 2 ) 5 CH 3

Branch Chain Alkanes Parent chain: the longest continuous carbon chain in an organic compound Substituent group: an atom or group that replaces a hydrogen in an organic compound; forms a branch off the parent chain Alkyl group: a carbon chain that forms a branch off a parent chain of a hydrocarbon Example: 2-methylbutane Notice the “methyl” group branched off the “butane” parent chain

Structural Isomers Some compounds share the same molecular formula but have a different structure; these are called structural isomers Example: Butane and 2-methylpropane

Naming Substituents

Naming and Drawing Alkanes 1.Identify the parent chain. 2.Identify all substituents. 3.Number the parent chain from the end so that the substituents are attached to the carbon atom with the lowest possible number. If the numbering is a tie, the group that comes first alphabetically gets the lowest number. 4.If the same substituent is present more than once, use a prefix to indicate this (di-, tri-, tetra-, etc.) 5.When writing the final name, list substituents in alphabetical order, ignoring any prefixes. Separate words by hyphens; separate numbers by commas. 6.If there are two possible ways to arrange a parent chain, use the simplest possible arrangement.

Practice: Naming Unbranched Alkanes 1. Name the following compounds: a) b)

Practice: Naming Branched Alkanes 1.Name the following compounds: a) b)

c) d)

Cyclic alkanes: or cycloalkanes; is a hydrocarbon in which the carbon atoms form a closed loop Nomenclature: -Has the prefix “cyclo-” added to the parent ring -C 3 H 6, cyclopropane, is the simplest cycloalkane. -General Formula for cycloalkanes: C n H 2n Cycloalkanes

Naming and Drawing Cycloalkanes 1.Identify the parent carbon ring. 2.Identify all groups/branches attached to the parent chain. 3.Number the carbons in the ring to give the groups/branches the smallest number. 4.If numbering is a tie, the group that comes first alphabetically gets the lower number. 5.If there is only one group or chain attached to a carbon in the ring, you do not have to include the number 1 because it is redundant.

Practice: Naming Cycloalkanes 1.Name the following compounds: a) b)

Practice: Drawing Alkanes 1.Draw structural formulas for each of the following : a)4-ethyl-3,5-dimethylnonane b) 7-ethyl-2-methyl-4-(propan-2-yl)decane c) 1-ethyl-2-propylcyclooctane

Practice: Drawing Alkanes (Solutions) 1.Draw structural formulas for each of the following : a)4-ethyl-3,5-dimethylnonane b) 7-ethyl-2-methyl-4-(propan-2-yl)decane c) 1-ethyl-2-propylcyclobutane

Alkyl halide: an alkane in which or more hydrogen atoms have been substituted with one or more halogen atoms Nomenclature: -Each halogen has a specific prefix added to the parent ring Fluorine is “fluoro-” Chlorine is “chloro-” Bromine is “bromo-” Iodine is “iodo-” -General Formula for alkyl halides: R-X (where R is the alkyl group and X is the halogen) Alkyl Halides

Practice: Naming Haloalkanes 1.Name the following compounds: a) b)

Practice Questions Page 17 #1-7