Nomenclature

Nomenclature of Alcohol

Determine the longest chain of carbon to which the hydroxyl is directly attached and name it Drop the final -e to suffix –ol E.g methane  methanol Number the longest chain so that the carbon atom bearing the hydroxyl group will have the lowest number.

Nomenclature of Alcohol

Common functional names of alcohol

Example Draw bond-line formulas and give IUPAC substituted names for all of the isomeric alcohol with the formula C 4 H 10 O

4.4 Monocyclic Compound Cycloalkanes with only one ring are name by attaching the prefix “cyclo-” to the name of the alkanes

Cyclic alkanes If a cyclic alkane and one substituent is present, no need to designated position of substituent

Cyclic alkanes If a cyclic alkane and two substituents are presented, we number the ring beginning with the substituent first in the alphabet and number in the direction that gives the next substituent the lower number possible

Cyclic alkanes If a cyclic alkane and three or more substituents are presented, we begin at the substituent that leads to the lowest set of locants

Cyclic alkanes When a single ring system is attached to a single chain with a greater number of carbon atoms, or when more than one ring system is attached to a single chain, then

4.4 Bicyclic compounds A compound is considered bicyclic is when it contains two fused or a bridged ring The name of bicyclicalkane is corresponding to the total number of carbon presented.

Bicyclic alkanes If substituents are present, we number the bridge ring system beginning at on bridge-head, proceeding first along the longest bridge to the other bridge-head. The shortest bridge is named last

4.5 Nomenclature of Alkenes and Cycloalkenes Rules for naming alkenes Identify and name the longest chain of carbon atoms that contain C=C Parent name contains suffix -ene Number the carbon chain from one to the other, so as to give the lowest number to a double bond Designated the location of the double bond to the parent name Identify substituents and their locations

4.5 Nomenclature of Alkenes and Cycloalkenes Rules for naming cycloalkenes Identify and name the longest chain of carbon atoms that contain C=C Parent name contains suffix -ene Number the carbon chain from one to the other, starting with the double bond Identify substituents and their locations

4.5 Nomenclature of Alkenes and Cycloalkenes Name compounds containing a double bond and an alcohol as alkenol (cycloalkenol) Give the alcohol carbon the lower number

4.5 Nomenclature of Alkenes and Cycloalkenes Two common alkenyl groups

4.5 Nomenclature of Alkenes and Cycloalkenes

If two identical substituents are on the same side of the double bond, the compound is designated cis If they are opposite, the compound is designated trans

Nomenclature of Alkynes Rules for naming an alkynes are similar to alkene BUT Parent name ends with -yne

Example Name the following compound Draw the geometric isomers of 2-butene. Label them cis and trans

Nomenclature of Alkynes Monosubstituted acetylene or 1-alkyne are called terminal alkynes

4.7 Physical Properties Alkanes and Cycloalkanes Boiling point: increases with increasing molecular weight - unbranched molecules (homologous series) Branched alkanes have lowers boiling point - affected by van der Waals forces

4.7 Physical Properties Alkanes and Cycloalkanes Melting Points: - increasing but does not show the same smooth curve - alternation from odd and even number of carbon atoms - alkane chains with an even number of carbon atom pack more closely in the crystalline state  higher mp  cycloalkanes also have higher m.p

4.7 Physical Properties Alkanes and Cycloalkanes Density: Alkanes and cycloalkanes are the least dense of all group in organic compound. E.g < 1.00 g/ml at 4 o C Solubility: alkanes and cycloalkanes are almost insoluble in water Due to their low polarity and inability to form H-bond “like dissolves like”

4.7 Physical Properties Alkanes and Cycloalkanes Recall Sigma (σ) bondPi (π) bond Created when “head on” overlap occurs of orbitals Created when “side on” overlap occurs of orbitals

4.7 Physical Properties Alkanes and Cycloalkanes Only sigma (σ) bond can undergo rotation about that bond with respect to each other Each possible structure that result from rotation of group about the signma bond is called confomormational isomers Types: Newman projection formula and sawhorse formula

Conformational isomers

Eclipsed conformation Staggered conformation Each hydrogen on one carbon as close as possible to one hydrogen on the other carbon Hydrogen on one carbon as far from the hydrogen from other carbon

Potential energy diagram

Conformational isomers G is a group or atom other than hydrogen Barriers to rotation are somewhat larger

4.9Conformational Analysis of Butane

Example Using Newman projections to draw out all possible conformations of 1,2-dibromomethane

Example Draw a plot of energy versus dihedral angle for the conformation of 2-methylbutane about the C2-C3 bond

Stereoisomers and Conformational Stereoisomers Stereoisomers have the same molecular formula and connectivity but different arrangements of atoms in 3-D Conformational Stereoisomers: Stereoisomers that are interconvertible with one another by bond rotation

The Relative Stabilities of Cycloalkanes: Ring Strain Carbon chains are confined in rings, cycloalkanes are much less flexible than monocyclic alkanes. Strain energy is measure from the amount of heat that is produced from combustion reaction Ring strain describe the destabilization of a cyclic molecule