Organic Chemistry Introduction Functional Groups Names and Structures Alkanes Cycloalkanes Alkenes Alkynes Alcohols

Introduction Organic chemistry is the study of carbon-containing compounds The field of organic chemistry is very important for a wide variety of reasons. A huge number of carbon-containing compounds are known. Most of the advances in the pharmaceutical industry are based on a knowledge of organic chemistry. Life as we know it is based on organic chemistry.

Introduction Most organic compounds have a “skeleton” that is composed of C-C bonds. The C-C bonds may be single bonds, double bonds, or triple bonds. Carbon forms a total of 4 bonds. The “skeleton” of an organic compound has H’s attached to it. other “heteroatoms” like O, halogens, N, S, and P may be present as well

Introduction propane methane acetylene acetone Some familiar organic compounds: propane methane acetylene acetone

Introduction Acetic acid “ether” aspirin Ethyl alcohol Some familiar organic compounds: Acetic acid “ether” aspirin Ethyl alcohol

Introduction Organic compounds are commonly classified and named based on the type of functional group present. An atom or group of atoms that influences the way the molecule reacts, behaves, or functions The center of reactivity in an organic compound

Functional Groups On your exam, you will be responsible for recognizing and naming the various common functional groups that are found in organic compounds: Use Table 25.4 and the following slides to help you study

Functional Groups Class of Compound Functional Group Alkane None Cycloalkane Alkyl halide Alkene Alkyne Alcohol Ether

Functional Groups Class of Compound Functional Group Aldehyde Ketone Carboxylic Acid Ester

Functional Groups Class of Compound Functional Group Amine Amide Nitrile Aromatic ring

Alkanes Contain C-C single bonds no functional group Tetrahedral electron domain geometry sp3 hybridized carbons Free rotation around single bonds propane

Cycloalkanes Contain C – C with at least 3 of the carbons arranged in a cyclic (ring) structure No functional group Tetrahedral ed geometry sp3 hybrid orbitals

Alkyl Halides Contain C-halogen bond F, Cl, Br, or I Alkyl halides are generally (but not always) polar molecules.

Alkenes Contain C=C (carbon-carbon double bonds) 1 sigma bond & 1 pi bond Trigonal planar geometry sp2 hybridized carbons Which atoms must be coplanar in an alkene? 1-propene

Alkenes The C=C present in an alkene is composed of 1 sigma (s) bond and 1 pi (p) bond. Double bonds are rigid and cannot rotate freely. Rotation would cause loss of overlap of the p orbitals, destroying the p bond. ethylene

Alkynes Contain C C (carbon-carbon triple bonds) 1 sigma bond 2 pi bonds Linear electron domain geometry sp hybridized carbons Which atoms must be co-linear in an alkyne?

Aromatic Ring Planar ring system with alternating single and double bonds does not react like an alkene Trigonal planar sp2 hybridized carbons Benzene ring is a very common aromatic ring. benzene pyridine

Functional Groups Alkanes are often called saturated hydrocarbons Organic compounds composed of carbon and hydrogen that contain the largest possible number of hydrogen atoms per carbon atom. Alkenes, alkynes, and aromatic hydrocarbons are called unsaturated hydrocarbons Organic compounds composed of carbon and hydrogen that contain less hydrogen than an alkane having the same number of carbon atoms

Alcohols Contain C-O-H bond hydroxyl group Alcohols form hydrogen bonds between molecules. How does hydrogen bonding affect boiling point??? Amphoteric

Ethers Contain C-O-C bond tetrahedral e.d. geometry why? bent molecular geo.

Amines Contain C-N-R R’ R and R’ can be H or C Primary and secondary amines form hydrogen bonds. Common organic bases lone pair of e- on N primary secondary tertiary

Aldehydes Contain (-CHO) Carbonyl (C=O) trigonal planar geometry always on the 1st or last carbon in a chain trigonal planar geometry sp2 hybrid orbitals

Ketones Contain Trigonal planar e.d. geo. sp2 hybridized C O C-C-C Carbonyl attached to middle of chain Trigonal planar e.d. geo. sp2 hybridized C

Carboxylic Acids Contain carboxyl group Form hydrogen bonds trigonal planar sp2 hybridized carbon

Esters Contain trigonal planar sp2 hybridized

Amides Contain C=O is trigonal planar & sp2 hybridized where R and R’ = H or C C=O is trigonal planar & sp2 hybridized

Nitriles Contain Linear sp hybridized C

Functional Groups Example: Identify the functional groups present in the following compounds. thyroxine testosterone

Functional Groups Example: Identify the functional groups in the following compounds. Lisinopril Vanillin

Depicting Structures of Organic Compounds Organic compounds can be depicted using a variety of formulas: Empirical formula Molecular formula Lewis structure Full structural formula Three dimensional drawings Condensed structural formula Line angle drawings

Depicting Structures of Organic Compounds Ethyl acetate is an organic molecule with: empirical formula = C2H4O molecular formula = C4H8O2

Depicting Structures of Organic Compounds Ethyl acetate is an organic molecule with: Lewis structure: depicts all covalent bonds using a straight line and shows all nonbonding pairs of electrons Full structural formula: a Lewis structure without the nonbonding electrons

Depicting Structures of Organic Compounds Ethyl acetate is an organic molecule with: 3-d drawing: Condensed structural formula Line angle drawing

Names and Structures of Alkanes Some of the simplest alkanes: You must know these!!!

Names and Structures of Alkanes Some of the simplest alkanes: You must know these!!!

Names and Structures of Alkanes The previous alkanes are also called straight-chain hydrocarbons: all of the carbon atoms are joined in a continuous chain Alkanes containing 4 or more carbons can also form branched-chain hydrocarbons (branched hydrocarbons) some of the carbon atoms form a “branch” or side-chain off of the main chain

Names and Structures of Alkanes An example of a straight chain hydrocarbon: C5H12 CH3CH2CH2CH2CH3 pentane Examples of a branched hydrocarbon: C5H12 CH3CHCH2CH3 CH3 CH3 CH3CCH3 CH3 2-methylbutane 2,2-dimethylpropane

Names and Structures of Alkanes The three structures shown previously for C5H12 are structural isomers: compounds with the same molecular formula but different bonding arrangements Structural isomers are unique compounds and generally have different properties: different melting points different boiling points often different chemical reactivity

Names and Structures of Alkanes Organic compounds can be named either using common names or IUPAC names. You must be able to name alkanes, cycloalkanes, alkyl halides, alkenes, alkynes, and alcohols with 10 or fewer carbons in the main chain (or ring) using the IUPAC naming system.

Names and Structures of Alkanes Alkane Nomenclature: Find the longest continuous chain of carbon atoms and use the name of the alkane with the same number of carbons for the base name of the compound: The longest chain is not always written in a straight line. Base name: heptane

Names and Structures of Alkanes Number the carbon atoms in the longest chain beginning with the end of the chain closest to a substituent groups attached to the main chain that have taken the place of a hydrogen atom on the main chain A substituent

Names and Structures of Alkanes Name and give the location of each substituent Common substituents: Halo group a halogen atom “Halo” groups are named using “halo”: Cl chloro Br bromo I iodo F fluoro

Names and Structures of Alkanes Common substituents: alkyl group A substituent that is formed by removing an H atom from an alkane the alkyl group attaches to the main chain at the carbon that has lost its H

Names and Structures of Alkanes Alkyl groups are named by replacing the “ane” ending of the parent alkane with the “yl” ending. Alkyl groups to know:

Names and Structures of Alkanes Alkyl groups to know (cont):

Names and Structures of Alkanes Methyl group 3-methylheptane Note: Separate numbers from letters using a hyphen. Separate groups of numbers using commas.

Names and Structures of Alkanes Alkane Nomenclature: When two or more substituents are present, list them in alphabetical order: Butyl vs. ethyl vs. methyl vs. propyl When more than one of the same substituent is present (i.e. two methyl groups), use prefixes to indicate the number. Give the location of each as well. Di = two Tri = three Tetra = four Penta = five Note: Ignore these prefixes when alphabetizing.

Names and Structures of Alkanes Additional rules: If each end of the longest chain has a substituent the same distance from the end, start with the end nearer to the second substituent. correct incorrect 3-chloro-2,5-dimethylhexane

Names and Structures of Alkanes Example: Name the following compounds:

Names and Structures of Alkanes You must also be able to draw the structure of an alkane when given the IUPAC name. Identify the main chain and draw the carbons in it Identify the substituents (type and #) and attach them to the appropriate carbon atoms on the main chain. Be sure to connect the proper atoms when drawing bonds. Add hydrogen atoms to the carbons to make a total of 4 bonds to each carbon

Names and Structures of Alkanes Example: Draw the condensed structure for the following compounds. Draw a line angle drawing for each. 2,2-dimethylbutane 2-bromo-3-ethylhexane

Names and Structures of Alkanes Example: Draw the condensed structure for the following compound. Draw a line angle drawing for it. 2-methyl-4-propyloctane

Names and Structures of Cycloalkanes Cycloalkanes are named by: Use cyclo as a prefix with the name of the alkane with the same number of carbons present in the ring as the base name. Identify the substituents present using name and position number: No position number is used if only one substituent is present. For 2 or more substituents, number the ring to give the lowest possible numbers for the substituted carbons.

Names and Structures of Cycloalkanes isopropylcyclohexane 1,1-dibromo-3-methylcyclopentane

Names and Structures of Cycloalkanes Example: Name the following compounds.

Names and Structures of Cycloalkanes Example: Draw the following compounds. 1-chloro-3-ethylcyclohexane bromocyclobutane