© 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity...

55
© 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis Bruice University of California, Santa Barbara

Transcript of © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity...

Page 1: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Alkenes Structure, Nomenclature,

and an introduction to Reactivity

• Thermodynamics

and Kinetics

Chapter 5

Paula Yurkanis BruiceUniversity of California,

Santa Barbara

Page 2: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Molecular Formula and the Degree of Unsaturation

molecular formula = CnH2n+2 – 2 hydrogens for every π bond or ring

degree of unsaturation = the total numbers of π bonds and rings

Page 3: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Compounds with Molecular Formula = C8H14

CnH2n+2 = C8H18

Therefore, C8H14 has two degrees of unsaturation.

compounds with six hydrogens and two degrees of unsaturation

Page 4: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Saturated and Unsaturated Hydrocarbons

Saturated hydrocarbons have no double bonds.

Unsaturated hydrocarbons have one or more double bonds.

Page 5: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Nomenclature of Alkenes

Replace “ane” of alkane with “ene.”

The functional group gets the lowest possible number.

Page 6: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Stereoisomers are Named Using a cis or trans Prefix

Page 7: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Nomenclature of Dienes

two double bonds = diene

Page 8: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Number in the direction so that the functional group

gets the lowest number.

Nomenclature of Alkenes

Page 9: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Substituents are stated in alphabetical order.

Nomenclature of Alkenes

Page 10: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Nomenclature of Alkenes

Page 11: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Nomenclature of Cyclic Alkenes

A number is not needed to denote the position of the functional group;

it is always between C1 and C2.

Page 12: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Nomenclature of Alkenes

Page 13: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Nomenclature of Alkenes

Page 14: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Vinylic and Allylic Carbons

vinylic carbon: the sp2 carbon of an alkene

allylic carbon: a carbon adjacent to a vinylic carbon

Page 15: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Double Bonds Have Restricted Rotation

Rotation about a double bond breaks the π bond.

Page 16: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Six Atoms of an Alkene are in the Same Plane

Page 17: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Alkenes Have Cis–Trans Isomers

Cis: The hydrogens are on the same side of the ring.

Trans: The hydrogens are on opposite sides of the ring.

cis trans

They have different configurations; they can be separated.They have different configurations; they can be separated.

Page 18: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Which Is Cis and Which Is Trans?

Page 19: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

The E,Z System of Nomenclature

Z = Zusammen (together) E = Entgegen (opposite)

Page 20: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Relative Priorities

The relative priorities of the two groups depends on the

atomic numbers of the atoms attached to the sp2 carbon.

Page 21: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

The E and Z Isomers

Page 22: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

E and Z

Page 23: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

E and Z

Page 24: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Isomers for Compounds withTwo Double Bonds

Page 25: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Reactions of Organic Compounds

Organic compounds can be divided into families.

All members of a family react in the same way.

The family a compound belongs to depends on its functional group.

Page 26: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Electrophiles

An electrophile has a positive charge,a partial positive charge,or an incomplete octet.

Page 27: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Nucleophiles

A nucleophile hasa negative chargeor a lone pair.

Page 28: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

A Nucleophile Reacts with an Electrophile

Your first organic reaction

is a two-step reaction.

Page 29: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Curved Arrows

Curved arrows are used to show the mechanism of a reaction.

The mechanism of a reaction is the step-by-step description of the process by which reactants are converted into products.

first step of the reaction

Page 30: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

second step of the reaction

The curved arrow shows where the electrons start from and where they end up.

Curved Arrows

Page 31: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

How to Draw Curved Arrows

Page 32: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

How to Draw Curved Arrows

Page 33: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

How to Draw Curved Arrows

Page 34: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

How to Draw Curved Arrows

Page 35: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Thermodynamics and Kinetics

Page 36: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

A Reaction Coordinate Diagram

A reaction coordinate diagram shows the energy changes that take place in each step of a reaction.

Page 37: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

The Equilibrium Constant

The equilibrium constant gives the concentration of reactants and products at equilibrium.

Page 38: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Exergonic and Endergonic Reactions

Page 39: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Gibbs Free-Energy Change (∆G°)

Page 40: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Calculating ∆H°

Page 41: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Page 42: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Reaction Coordinate Diagrams for Fast and Slow Exergonic and Endergonic Reactions

Page 43: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Free Energy of Activation (∆G‡)

The free energy of activation is the energy barrier of the reaction.

Page 44: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Rate of a Reaction

Increasing the concentration increases the rate.

Increasing the temperature increases the rate.

The rate can also be increased by a catalyst.

Page 45: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

The Rate of a Reaction versusThe Rate Constant for a Reaction

Page 46: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

The Rate of a Reaction versusThe Rate Constant for a Reaction

Page 47: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

The Arrhenius Equation

The value of A pertains to the frequency and orientation of collisions.

e–Ea/RT

The term e–Ea/RT provides the reaction of molecules withthe needed activation energy at a given temperature (T).

Page 48: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

An Electrophilic Addition Reaction

Transition states have partially formed bonds.

Page 49: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Reaction Coordinate Diagram forEach Step of the Addition of HBr to 2-Butene

Page 50: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Reaction Coordinate Diagram forthe Addition of HBr to 2-Butene

The rate-limiting step of the reaction is the step that has its transition state at the highest point of the reaction coordinate diagram.

Page 51: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

A Catalyst

A catalyst provides a pathway for a reaction with a lower energy barrier.

A catalyst does not change the energy of the starting point (the reactants) or the energy of the end point (the products).

Page 52: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Enzymes

Most biological reactions require a catalyst.

Most biological catalysts are proteins called enzymes.

The reactant of a biological reaction is called a substrate.

Page 53: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

The Active Site of an Enzyme

An enzyme binds its substrate at its active site.

Page 54: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Enzyme Side Chains that Bind the Substrate

Some enzyme side chains bind the substrate.

Some enzyme side chains are acids, bases, and nucleophilesthat catalyze the reaction.

Page 55: © 2014 Pearson Education, Inc. Alkenes Structure, Nomenclature, and an introduction to Reactivity Thermodynamics and Kinetics Chapter 5 Paula Yurkanis.

© 2014 Pearson Education, Inc.

Some enzyme side chains are acids, bases, and nucleophiles that catalyze the reaction.

Enzyme Side Chains that Catalyze the Reaction