Hydrocarbons... Contain only hydrogen and carbon. Types: Alkane: single bonds; saturated (largest possible number of hydrogens/carbon atom. [C n H 2n+2 ] Alkene: one or more carbon-carbon double bond. Unsaturated hydrocarbon. Alkyne: one carbon-carbon triple bond. Unsaturated hydrocarbon. Aromatic: carbon atoms connected in a planar ring. Unsaturated hydrocarbon.
Hydrocarbons... Relatively nonpolar. (covalent bonds) Insoluble in water. (like dissolves like) Less volatile with increasing molar mass. (because of London dispersion forces)
Alkanes... [C n H 2n+2 ] Methane: CH 4 major component of natural gas; home heating; gas stoves; hot water heaters Ethane: C 2 H 6 Propane: C 3 H 8 used for home cooking and heating; gas grills Butane: C 4 H 10 disposable lighters and fuel canisters for gas camping stoves.
Name consists of Prefix Where are the substituents? 2.Parent How many carbons in the longest chain? 3. Suffix Which family? If two different chains of equal length are present: choose the one with the larger number of branch points as the parent.
Rules for naming alkanes... Longest continuous chain of carbon atoms gives the root name 1. For alkanes, add –ane to the root: Meth: C Eth: C 2 Prop: C 3 But: C 4 2. For alkanes beyond butane, use the Greek root for the number of carbons then add -ane to the end. C-C-C-C-C-C = hexane pent=5; hex=6; hept=7; oct=8; non=9; dec= 10
Substituent Group(s) added in place of a removed hydrogen.
Alkanes as a substituent group... Alkyl substituents: 1. Remove a hydrogen from the alkane. C 2 H 6 is ethane 2. Drop the -ane and add -yl. -C 2 H 5 is ethyl
Positions of substituent groups are specified by numbering the longest chain sequentially. (Use the lowest number for the position of the substituent group) The location and name of the substituent group is followed by root alkane name. 3-methylhexane C C-C-C-C-C-C
Substituents in alphabetical order. Use di-, tri-, etc. to indicate multiple identical substituents.
Cyclic Alkanes... C n H 2n Cycloalkanes Smaller than five carbons, very reactive. Rings of carbon atoms. Isomers Cis: both substituents are on the same side of the ring. Trans: substituents are on opposite sides of the ring.
Reactions of Alkanes.... Combustion: react with oxygen produce carbon dioxide and water Substitution: halogen atoms replace hydrogen atoms Dehydrogenation reactions:hydrogen removed forms double bond there unsaturated hydrocarbon is the product
Alkenes Root hydrocarbon (longest chain containing double bond) name ends in –ene. 2. More than three carbon atoms, the location of the double bond is indicated by the lowest numbered carbon atom in the bond. If equidistant: begin at end closer to substituent group. CH 2 =CHCH 2 CH 3 1-butene CH 3 CH=CHCH 3 2- butene 3. More than one double bond Indicate the position of each and use –diene, triene, tetraene...
Cycloalkenes... Name same as alkenes. Number so double bond is between C1 and C2 and the first substituent has the lowest number possible.
Alkynes... Unsaturated hydrocarbons contain atleast one triple carbon-carbon bond. -yne replaces –ane. Begin numbering chain at end closest to triple bond. More than one bond: -diynes, -triynes. Double and triple bonds: -enynes Start numbering from end nearer first bond. (if there is a choice. Usually double bonds get lower numbers than triple.)
Reactions of Alkenes and Alkynes... Addition reactions: double bond broken and new bonds formed to atoms added. Hydrogenation reactions: addition of hydrogen atoms Halogenation: addition of a halogen Elimination:one reactant splits apart to give two products. Substitutions: two reactants exchange parts to give two new products. Rearrangement:one reactant undergoes a reorganization of bonds and atoms to give a new product.
Aromatic Hydrocarbons... Benzene and its structural relatives Monosubstituted benzene: named as other hydrocarbons, with benzene as parent name. If substituent larger than ring (six carbons) : benzene becomes substituent group called phenyl. Disubstituted benzene: ortho:1,2 meta-1,3 para-1,4 More than two: number the position of each substituent group.
Alcohols... Alcohols: presence of an –OH (hydroxyl group) Nomenclature: replace final -e of parent hydrocarbon with –ol. (parent: longest chain containing –OH) Position of –OH specified by number- lowest number. Classified by: number of hydrocarbon fragments bonded to carbon where –OH group is attached. eg.C-C-C-Cor C-C-C-C or C C-C-C
Alcohols.... Polar Higher boiling points than expected from molecular weights. Intermolecular attractions. –OH extensive hydrogen bonding.
Aldehydes... Nomenclature: remove –e replace with –al. Longest chain as base name,must contain the carbonyl group. Aldehyde carbon assigned number 1, when subtituent positions are listed in the name. Bonded to at least one hydrogen atom. Number indicates position of carbonyl group.
Carboxylic Acids... Two systems: aldehyde and alcohol Derived from open chain alkanes: Carboxyl carbon is always C1. Replace terminal –e of alkane with –oic acid. -COOH group bonded to a ring, the suffix – carboxylic acid is used. The carboxylic acid carbon is attached to C1 and is not itself numbered in this system.