7.3 – Functional Groups Part 1 – Halocarbons & Alcohols

Functional Groups Functional groups are groups of atoms found within molecules that are involved in the chemical reactions characteristic of those molecules. Hence the name, they are simply groups of atoms that can be attached to a hydrocarbon chain and have a specific FUNCTION This allows for different characteristics, reactions, etc. Functional groups can pertain to any molecules, but you will usually hear about them in the context of organic chemistry. The symbol “R” refers to a hydrogen or hydrocarbon side chain that is attached to a functional group

Functional Groups Type Structure Functional group Halocarbon R-F (Cl, Br, or I) halogen Alcohol R-OH hydroxyl װ װ

Halocarbons Halocarbons are organic compounds that contain one or more covalently bonded halogens. The functional group is the halogen atom Halogens include: Fluorine Chlorine Bromine Iodine

Naming Haloalkanes IUPAC names for halogen substituents are: Fluorine = fluoro- Chlorine = chloro- Bromine = bromo- Iodine = iodo- The halo-substituents are numbered and arranged alphabetically, like we did before

Nomenclature of Halogens Number the main (longest) carbon chain so that the halogen will have the lowest number. Number the position of the halogen. Alkanes always end in ane. Use the same prefixes as before to name the main carbon chain. If there are alkyl groups in addition to halogens attached to the main chain; the halogen’s position and name come first when naming.

Types of Halocarbons: Primary Halocarbons where a halogen is on a carbon attached one other carbon

Types of Halocarbons Secondary Halocarbons: the halogen is on a carbon that is attached to two other carbons

Types of Halocarbons Tertiary Halocarbons: halogen is on a carbon that is attached to three other carbons

Other substituents Use the same naming rules Number position on the parent chain Put in alphabetical order 2-chlorobutane 3-bromo-2-chlorobutane Also, 2,2-dibromo-4-methylpentane is a good example of knowing which end to count from

Haloalkanes - Examples An alkane in which halogen atoms replace one or more hydrogens Used as solvents and anesthetics CFC’s (chlorofluorocarbons) were used a propellants in aerosols React with ozone in the upper atmosphere Resulted in ozone depletion over the Antarctic

Alcohols Alcohols are compounds in which one or more hydrogen atoms in an alkane have been replaced by a hydroxyl group. (-OH)   The name of the alkane chain loses the terminal "e" (from ane)and adds "ol",

Nomenclature of Alcohols Naming and Numbering Alcohols: The longest chain of carbon atoms containing the –OH group is selected as the parent. alkane chain is numbered from the end closer to the –OH group. To show the compound is an alcohol, the suffix –e of the parent alkane is changed to –ol.

Nomenclature of Alcohols Naming and Numbering Alcohols: A number is used to show the location of the –OH group. In the numbering of the parent chain, the location of the –OH group takes precedence (given the lowest number)over alkyl groups and halogen substituents For cyclic alcohols, numbering begins at the carbon bearing the –OH group.

Alcohols Examples of alcohols: Methanol Ethanol 2 1 1

Alcohols

Designation of Alcohols Much like halocarbons, alcohols can be designated as primary, secondary or tertiary based on the extent of carbon substitution Alcohols Primary Secondary Tertiary

C6H12O6(aq) →2 CH3CH2OH(aq) + CO2(g) Alcohols - Formation Fermentation Fermentation is the production of ethanol from sugars by the action of yeast. C6H12O6(aq) →2 CH3CH2OH(aq) + CO2(g) Humans have long taken advantage of this process in making bread, beer, and wine.

Alcohol - Formation In brewing, alcoholic fermentation is the conversion of sugar into carbon dioxide gas (CO2) and ethyl alcohol. This process is carried out by yeast enzymes. This is in fact a complex series of conversions that bring about the conversion of sugar to CO2 and alcohol. Yeast is a member of the plant family and in brewing we use the sugar fungi form of yeast. These cell gain energy from the break down of the sugar. The by-product, CO2, bubbles through the liquid and dissipates into the air. The other by-product alcohol, remains in the liquid which is great for us but not for the yeast, as the yeast dies when the alcohol exceeds its tolerance level.