Hydrocarbon Compounds Functional Groups Organic Chemistry Hydrocarbon Compounds Functional Groups

Organic Chemistry Involves Carbon Carbon atoms form bonds with other atoms and also with other carbon atoms to form RINGS OR LONG CHAIN MOLECULES Living things contain many carbon compounds

Characteristics of Organic Compounds All have covalent bonds Generally nonpolar molecules Therefore, many are soluble in nonpolar solvents not water “like dissolves like” (ex: Gasoline) Have LOW MELTING POINTS/HIGH VAPOR PRESSURES Held together by weak intermolecular forces Have you ever seen or heard of “solid” gasoline? Most are nonelectrolytes because they do not form ions

Hydrocarbons Homologous Series of Hydrocarbons - similar properties and related structures Alkanes, -enes & -ynes: Contain any number of carbon atoms, one after the other, in a long straight chain (table Q) As the chain gets longer (i.e. MORE CARBON ATOMS) -molecular size INCREASES (duh!) -Intermolecular forces between molecules INCREASES – Vander Waals force increases and the molecules start to intertwine (wrap together) Since intermolecular forces increase then Boiling points INCREASE while Freezing points Decrease (just like solutions) Prefixes tell you how many carbon atoms are in the chain (table P) Ethane C2H6 Ethene C2H4 Ethyne C2H2

Saturated and Unsaturated Compounds Hydrocarbon Compounds can be separated into Saturated & Unsaturated compounds Saturated: All carbon-to-carbon bonds are single -Unsaturated: At least one of the carbon-to-carbon bonds is a double or triple bond Are the following compounds Saturated or Unsaturated? - Saturated - Unsaturated Unsaturated  Saturated 

Butter – is a mixture of triglycerides of several different fatty acids

Naming the Hydrocarbons Follows IUPAC naming system: (International Union of Pure & Applied Chemistry): Need to identify where double & triple bonds are located in the chain by assigning a number Rules for naming (page 702 in textbook): – Find the longest Carbon Chain Number the Carbons in the chain so that the lowest # possible is associated with the double or triple bond (NOTE: LOOK both “Left to Right” Direction & “Right to Left” Direction) Select Prefix from Table P based on the longest chain carbon Combine carbon prefix with either –ane, -ene or yne ending based upon carbon to carbon bonds Give position number to double bond or triple bond Combine name with # carbon followed by “-” and then Hydrocarbon name 1-butene 2-butene

Isomers Compounds that have the SAME molecular formula (same atoms in the same molar ratio) but DIFFERENT structural formulas are called isomers different compounds with different names and different physical properties such as boiling and melting point Example: CH3OCH3 and C2H5OH OR Pentane Methyl Butane

Methyl (-CH3) Groups Methyl propane Butane Pentane Methyl Butane If more than 1 methyl group, use di for 2, tri for 3, etc. in front of the Homologous Series Name Methyl propane Methyl Group Butane Pentane Methyl Butane Methyl Group

Di, Tri, … What is the longest continuous chain of carbons here? (3 Carbons) so Propane Any Methyl? How Many Methyl Groups? Therefore Name is: Dimethyl Propane

Functional Groups TABLE R – Organic Functional Groups Some organic compounds have one or more hydrogen atoms replaced by a particular arrangement of atoms known as a functional group TABLE R – Organic Functional Groups The symbol R, R’ & R” are used to represent any carbon chain Ethanol (R-OH) R in this case is:

Names of Functional Groups See Example column on Table R & note the ENDING Carbon in the chain is numbered so carbon with –the functional group attached has lowest possible number 2-butanol ethanol If more than one functional group - then prefixes di, tri, tetra ,etc. are added (usually for Halides) Cl Cl 1,2-dichlorobutane

Organic Reactions Organic reactions tend to proceed at a much slower rate than inorganic reactions. Organic compounds undergo several reactions where usually only the functional group is involved The larger part of the reacting molecule often remains unchanged during the reaction

Substitution Reactions Replacing one atom or group of atoms with a different one (similar to Double Replacement) Only saturated hydrocarbons or alkanes An alkane (all single C-C bonds), a halogen replaces a hydrogen atom to produce a halocarbon + Br2  + HBr hydrogen bromide ethane bromine bromoethane

Addition (If hydrogen is added it’s called hydrogenation) Similar to a SYNTHESIS reaction Limited to alkenes & alkynes (unsaturated hydrocarbons) Involves breaking apart the double or triple bond and adding two or more atoms to carbon atoms Characterized by the formation of a single product ethene bromine 1,2-dibromoethane

Fermentation enzyme C6H12O6  2 C2H5OH + 2 CO2 can occur in living systems enzymes acts as catalysts to break down organic molecules enzyme C6H12O6  2 C2H5OH + 2 CO2 glucose ethanol carbon dioxide

ALCOHOL + ACID ------ ESTER + WATER Esterification An alcohol and an acid form an ESTER and water Esters have 2 names – the first name is derived from the alcohol name with a –yl ending. The second name comes from the organic acid with a –ate ending Esters are responsible for the aromas associated with fruits, flowers and leaves ALCOHOL + ACID ------ ESTER + WATER +  + H2O Methyl ethanoate water methanol ethanoic acid

Saponification Making of organic salts or “SOAP” Hydrolysis (break down) of fats by bases Soaps have both a polar end and a non-polar end Therefore they can bring polar (water) and non-polar (grease) solutes together The reason why a soapy sponge will clean a greasy countertop, but just water will not

Ester (fat) + NaOH → SOAP + glycerol

Polymerization Polymers are molecules composed of repeating units – “PLASTICS” Very, Very, Very long chains of carbons all bonded in a chain Smaller hydrocarbon molecules combine to form very long and large molecules Ex. Sodium polyacrylate Occurs in nature in the production of proteins and starches

Sodium Polyacrylate