Brown, LeMay Ch 25 AP Chemistry Organic Chemistry Brown, LeMay Ch 25 AP Chemistry

25.1: Organic Chemistry The study of carbon compounds, but not limited to living systems Biochemistry: study of the chemistry of living things Functional group: a group of atoms which determine how a molecule functions or reacts A part of a molecule that is not part of the “base” carbon chain Also called a substituent

25.2: Intro to Hydrocarbons Compounds composed of only C and H Combust to form CO2 and H2O Types: Alkanes: contain only single C-C bonds Also called saturated (contain the maximum # of H’s) Unsaturated: contain < maximum # of H’s Alkenes: contain at least one C=C bond Alkynes: contain at least one C≡C bond Aromatics: C’s connected in a planar ring (contain s and p bonds) and have delocalization

25.3: Alkanes Lewis structure vs. condensed structural formula Ex: C4H10 H3C–CH2–CH2–CH3 CH3CH2CH2CH3

Structural isomers Compounds with same formula but different structures (different bonding arrangements) Free rotation around C-C bonds limits number of isomers of alkanes * Straight-chain n- all C in a continuous chain * Branched iso- one CH3 branched off t- or neo- lower-case “t”-shaped “n-” means normal There are 18 possible isomers for C8H18, and 75 possible isomers for C10H22.

Ex: Draw all the structural isomers for... CH4 C2H6 C3H8 C4H10 C5H12

Organic Nomenclature prefix base suffix What substituents? What “family”? How many carbons? Originally formulated by IUPAC in 1892 (http://www.acdlabs.com/iupac/nomenclature/) Find the longest continuous chain of C atoms; use the name of this chain as the base of the compound’s name. 1 = meth- 2 = eth- 3 = prop- 4 = but- 5 = pent-6 = hex- 7 = hept- 8 = oct- 9 = non- 10 = dec- IUPAC = International Union of Pure and Applied Chemistry

Number the C atoms in the longest chain, beginning with the end nearest to a substituent. If different substituents are present, give the lowest number to the substituent with highest priority (see list). (http://www.chem.ucalgary.ca/courses/351/Carey5th/nomenclature/functional/func.html) Name and give the location (carbon #) of each substituent as prefixes or suffixes. (It varies.) When 2 or more substituents are present, name them in alphabetical order as prefixes When 2 or more of the same substituents are present, use a Greek prefix (di-, tri-, tetra-, penta-, hexa-, …)

Ex: Name all the molecules. CH4 C2H6 C3H8 methane ethane propane butane 2-methylpropane pentane 2,2-dimethylpropane 2-methylbutane

Saturated hydrocarbons Alkanes: CnH2n+2; suffix is -ane Cycloalkanes: CnH2n (n>2); prefix is cyclo- C’s bonded in a ring; not planar like an aromatic compound (except cyclopropane) Ex: Draw Lewis structures of the first 4 cycloalkanes and name them. cyclobutane cyclopropane cyclopentane cyclohexane

25.4: Unsaturated hydrocarbons Alkenes: CnH2n; prefix is bond #; suffix is –ene (more than one double bond: –diene, -triene) Geometrical isomers: same formula & same groups, but different structures. cis- groups with highest priority on same side of bond axis (high priority = high atomic mass) trans- groups with highest priority diagonal/across the double bond Ex: Draw and name all the isomers of C4H8. y y x x

Alkynes: CnH2n-2; prefix is bond #; suffix is –yne Reactions: unsaturated molecules are more chemically reactive than saturated compounds Addition: H3C-C≡C-CH3 + Br2 → ? Hydrogenation: CH3-CH=CH-CH3 + H2 → ? → H3C-C=C-CH3 | Br Br―Br Manufacturers hydrogenate the oil in peanut bitter so it will not separate from the peanut part. → H3C-CH―CH-CH3 | H H―H

Aromatics: named like alkanes, but primarily based on benzene Prefix describes relative positions of substituents: ortho- 2 substituents next to each other meta- 2 substituents separated by one C para- 2 substituents separated by two C’s ortho- meta- para- Naphthalene: “mothballs”

25.4 – 25.5: Functional Groups Notation: “R” stands for: Alkyl group, such as -CH3 -C2H5 -C3H7, etc. H

Ester Name of group Formula of group Suffix Name Example structure Example chemical name Carboxylic acid O || R-C-OH or “R-COOH” -oic acid Ester R-C-O-R “R-COOR” -yl ___oate

Ketone R-O-H Alcohol “R-OH” -al -one R-C-R Aldehyde O || R-C-H or “R-CHO” -al Ketone R-C-R -one Alcohol R-O-H “R-OH” -ol (suffix if highest priority) hydroxyl- (prefix if lower priority)

Ether R-C-O-C-R ___ ether Amine R-NH2 -amine NH2 NH2

(bromo-, chloro-, fluoro-, iodo-) Alkene \ / C=C / \ -ene Alkyne R-C≡C-R -yne Halide R-X halo- (bromo-, chloro-, fluoro-, iodo-)

C ring with double bond(s) Cycloalkane C ring cyclo-___-ane Cycloalkene C ring with double bond(s) cyclo-___-ene Alkane -(CH2)n-CH3 -yl

*25.7: Chirality Chiral: a molecule having a nonsuperimposable mirror image (Originally discovered by Louis Pasteur) Compounds containing C atoms with four different substituents are inherently chiral Optical isomers or enantiomers: nonsuperimposable mirror images Labeled “L” (levo, left-handed) and “D” (dextro, right-handed) Racemic: a mixture containing both enantiomers (both L and D) http://nobelprize.org/educational_games/chemistry/chiral/