1. Alcohols and Alkyl Halides: Introduction to Reaction Mechanisms
Chapter 5
Alcohols and Alkyl Halides:
Introduction to Reaction Mechanisms
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2. Section 5.1
FUNCTIONAL GROUPS

3. Functional Groups-1
Alkanes are not generally considered to be functional groups (although C–H bonds can be reactive)
The multiple bonds in alkenes and alkynes are considered functional groups
The six-membered rings consisting of 𝑠𝑝 2 hybridized carbons in arenes are considered functional groups
In this chapter, we will focus on alcohols (ROH) and alkyl halides (RX, X = F, Br, Cl, I)

4. Survey of Functional Groups

5. Survey of Functional Groups-1

6. Survey of Functional Groups-2

7. IUPAC NOMENCLATURE OF ALKYL HALIDES
Section 5.2
IUPAC NOMENCLATURE OF ALKYL HALIDES

8. Two Types of Nomenclature
There are two distinct types of nomenclature for alkyl halides:
Functional class nomenclature: the alkyl group is treated as the “positive” portion of a halide salt

9. Two Types of Nomenclature-1
There are two distinct types of nomenclature for alkyl halides:
Functional class nomenclature: the alkyl group is treated as the “positive” portion of a halide salt
Substitutive nomenclature (preferred): the halogen is treated as a “halo-” substituent on an alkyl chain

10. IUPAC NOMENCLATURE OF ALCOHOLS
Section 5.3
IUPAC NOMENCLATURE OF ALCOHOLS

11. Two Types of Nomenclature-2
The two types of nomenclature we saw for alkyl halides apply to alcohols as well:
Functional class nomenclature: the alcohol is named as an “alkyl alcohol”; the alkyl group is treated as a substituent

12. Two Types of Nomenclature-3
The two types of nomenclature we saw for alkyl halides apply to alcohols as well:
Functional class nomenclature: the alcohol is named as an “alkyl alcohol”; the alkyl group is treated as a substituent
Substitutive nomenclature (preferred): the alcohol is named as an “alkanol,” with a number before “alkan” or “ol” to denote the position of the –OH group
Either the “n-alkanol” or “alkan-n-ol” names are acceptable.

13. Substitutive Nomenclature
When using the substitutive convention, it is important that the parent chain includes the –OH or –X substituent
For the purposes of numbering, the –OH group takes precedence over halogen substituents and alkyl groups

14. CLASSES OF ALCOHOLS AND ALKYL HALIDES
Section 5.4
CLASSES OF ALCOHOLS AND ALKYL HALIDES

15. Substitution pattern can profoundly affect the reactivity of a carbon!
Alcohols, alkyl halides, and other organic compounds are often classified by substitution pattern
The key question is: how many alkyl groups are attached directly to the carbon that bears the functional group?
One alkyl group: primary (𝟏°)
Two alkyl groups: secondary (𝟐°)
Three alkyl groups: tertiary (𝟑°)
Substitution pattern can profoundly affect the reactivity of a carbon!
One attached alkyl group; Two implicit hydrogens
Two attached alkyl groups; Two implicit hydrogens

16. BONDING IN ALCOHOLS AND ALKYL HALIDES
Section 5.5
BONDING IN ALCOHOLS AND ALKYL HALIDES

17. Hybridization, Geometry, and Bonding
The carbon bonded to –OH or –X is 𝑠𝑝 3 hybridized and tetrahedral
The C–O and C–X bonds are polarized toward the more electronegative O or X atom
The carbon atom bonded to O or X is partially positive

18. Dipole Moments
Because the C–O and C–X bonds are polarized, alcohols and alkyl halides are polar!
Dipole moments are comparable to that of water
Note the direction of the dipole vector and the implied partial charges on C, O, and X

19. Electrostatic Potential Maps
In both compounds, the heteroatom bears significant negative charge
In methanol, the O–H hydrogen bears most of the positive charge
In chloromethane, the nearby C–H hydrogens bear most of the positive charge