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Nomenclature. Nomenclature of Alcohol Determine the longest chain of carbon to which the hydroxyl is directly attached and name it Drop the final -e.

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Presentation on theme: "Nomenclature. Nomenclature of Alcohol Determine the longest chain of carbon to which the hydroxyl is directly attached and name it Drop the final -e."— Presentation transcript:

1 Nomenclature

2 Nomenclature of Alcohol

3 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.

4 Nomenclature of Alcohol

5 Common functional names of alcohol

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

7 4.4 Monocyclic Compound Cycloalkanes with only one ring are name by attaching the prefix “cyclo-” to the name of the alkanes

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

9 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

10 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

11 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

12 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.

13 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

14 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

15 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

16 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

17 4.5 Nomenclature of Alkenes and Cycloalkenes Two common alkenyl groups

18 4.5 Nomenclature of Alkenes and Cycloalkenes

19 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

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

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

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

23 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

24 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

25 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”

26 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

27 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

28 Conformational isomers

29 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

30 Potential energy diagram

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

32 4.9Conformational Analysis of Butane

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

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

35 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

36 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


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