Lesson 02a - Intro to Functional Groups

SCH4 Organic – Lesson 2a ORGANIC FUNCTIONAL GROUPS • • • Organic compounds are grouped into classes. The properties & reactions of a particular class are similar & are determined by the functional group. A functional group is a recognizable combination of atoms (other than C—C & C—H bonds) within an organic molecule. COMMON FUNCTIONAL GROUPS: • Carbon-carbon multiple bonds o (C=C , CC) • Single bonds between carbon & a more electronegative atom o ( C—O, C—N, C—Cl ) • Double bond between C & O o (C=O) PROPERTIES OF ORGANIC MOLECULES: The properties of an organic molecule are primarily determined by the reactivity & polarity of the functional group. Polar? Strongest Intermolecular Forces MP / BP Solubility in Water NO dispersion forces low low YES dipole-dipole forces med med YES (and H—N or H—O) H-bonding high high ORGANIC HALIDES Fn’l Group: Properties: Uses: • • • a halogen R-Cl R-F R-Br R-I “R” = rest of hydrocarbon (HC) chain (an “alkyl” group) • Polar (depending on number & position of halogens) • • insecticides refrigerants eg. chloroethane SCH4 Organic – Lesson 2a Nomenclature 1. Root: Name the longest hydrocarbon chain that has the halogen attached to it. This is called the parent chain. 2. Prefix: - Number the parent chain from the end closest to the functional group. - Number and name the halogen as a prefix to the parent chain. The prefixes are: fluoro-, chloro-, bromo-, or iodo- Number & name any other substituents (in alpha order) Example: 2,3-dichlorobutane Practice: 2-fluoropropane 3-chloro-2-iodo-3-methylpentane **Chain numbering priority** 1.Any other functional group 2.C=C or C  C 3.Halogen 4.alkyl NOTE: Isomers have the same chemical formula. A double bond prevents the structure from rotation and therefore can “lock” the structure into a 3D shape. If the C at each end of the double bond has two different substituents attached, it can be further classified as trans (substituents on opposite sides) or cis (substituents on the same side). Example: SCH4 Organic – Lesson 2a ETHERS Fn’l Group: an ether linkage • Properties: Uses: R-O-R’ O • Polar • • lock de-icer solvent (will dissolve both polar and non-polar substances) R R’ Nomenclature 1. Root and suffix: Name the longest continuous HC chain as the parent chain. 2. Prefix: - The shorter HC chain & O together are considered the substituent. Name & number them as an “alkoxy” group (Number where the alkoxy group comes off the parent chain) - Name & # any other substituents before the chain they come off, always numbering closest to the functional group. Eg: 2-ethoxybutane Practice: CH3-CH2-CH2-CH2-O-CH2-CH3 CH3-O-CH2-CH2-CH3 3-propoxyheptane ethoxyethane 2-methyl-1-butoxypentane SCH4 Organic – Lesson 2a Lesson 2a Practice HALOALKANES 1. Name the following molecules. Identify the longest chain, and number so that the halogen(s) has the lowest values possible. Identify numbers for other substituents. List substituents in ABC order. a) b) c) d) 2. Draw condensed structural diagram and a line structural diagram for each of the following molecules. a) 1-iodopropane c) 3-bromo-2,2-dimethylpentane b) 2-chloro-1-fluoroethane d) 2,4-dibromo-3-chlorohexane 3. These compounds have an error in their names! Draw the compounds and rename them correctly. a) 3-chlorobutane b) 4-chloro-3-bromohexane SCH4 Organic – Lesson 2 ETHERS 4. Name the following molecules. Identify the longest chain, and number so that the halogen(s) has the lowest values possible. Identify numbers for other substituents. List substituents in ABC order. a) b) 5. Draw condensed structural diagram and a line structural diagram for each of the following molecules. a) Methoxyethane c) 2-ethoxypentane b) 2-propoxybutane d) 3-ethoxy-4-methylhexane 6. These compounds have an error in their names! Draw the compounds and rename them correctly. a) 3-propoxymethane b) 4-methoxy-4-methylbutane