{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chapter 3 Notes - Chapter3 Reactions:AcidsandBases...

Info icon This preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 3 An Introduction to Organic Reactions: Acids and Bases
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Reactions and Their Mechanisms There are four general types of organic reactions: Substitutions Additions Eliminations
Image of page 2
Rearrangements Cleavage of Covalent Bonds Homolysis Heterolysis
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
In Class Problem: Designate each of the following reactions as (a) a substitution, (b) an elimination, (c) an addition, (d) a rearrangement, or (e) some combination of the former.
Image of page 4
Heterolytic reactions almost always occur at polar bonds. The reaction is often assisted by formation of a new bond to another molecule. The following two examples illustrate two types of heterolytic cleavage reactions: (1) An example of a unimolecular reaction process:
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
(2) An example of a bimolecular reaction process:
Image of page 6
Introduction to Acid‐Base Chemistry Brønsted ‐Lowry Definition of Acids and Bases Acid: a substance that can donate a proton. Base: a substance that can accept a proton. Example: Hydrogen chloride is a very strong acid. When dissolved in water essentially all hydrogen chloride molecules transfer their proton to water. Example: Aqueous hydrogen chloride and aqueous sodium hydroxide are mixed. The actual reaction is between hydronium and hydroxide ions.
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Lewis Definition of Acids and Bases Lewis Acid: electron pair acceptor Lewis Base: electron pair donor (Curved arrows show movement of electrons to form and break bonds.) Opposite Charges Attract and React BF 3 and NH 3 react based on their relative electron densities. BF 3 has substantial positive charge on the boron. NH 3 has substantial negative charge localized at the lone pair on nitrogen.
Image of page 8
In Class Problem: Write an equation that shows the Lewis acid and Lewis base in the reaction of (a) molecular chlorine (Cl 2 ) with aluminum chloride (AlCl 3 ). (b) boron trifluoride (BF 3 ) with tert‐butyl alcohol ((CH 3 ) 3 COH).
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Heterolysis of Bonds to Carbons: Carbanions and Carbocations Reaction can occur to give a carbocation or carbanion depending on the nature of Z. Carbocations (Lewis acids) have only 6 valence electrons and a positive charge. Carbanions (Lewis bases) have 8 valence electrons and a negative charge.
Image of page 10
Organic Chemistry Terms for Lewis Acids and Bases Electrophiles (“electron‐loving” reagents ): seek electrons to obtain a stable valence shell of electrons. They are electron‐deficient species e.g. carbocations. Nucleophiles (“nucleus‐loving” reagents): seek a proton or some other positively charged center. They are electron‐rich species e.g. carbanions. The Use of Curved Arrows in Illustrating Reactions Curved arrows show the flow of electrons in a reaction and not the movement of atoms. An arrow starts at a site of higher electron density (a covalent bond or unshared electron pair) and points to a site of electron deficiency.
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern