Chem 125 Review12/14/05

Projected material

This material is for the exclusive use of Chem 125 students at Yale and may not

be copied or distributed further.

It is not readily understood without reference to notes from the lecture.

Functional Group Names

RED: Memorize & Identify HOMO/LUMO

BLUE: Memorize

Substitution of Cl for H• •

H CH3Cl Clweak bond

(58 kcal/mole)

••

SOMO

H Cl

•

CH3 Cl Cl

CH3Cl

•

Cl

single-electrons

single-barbedarrows

"free-radical chain"

Cl Cl*

C

CH2

H2

••

+*n

+

Addition of Cl2 to an Alkene

ClC

CCl

H2

H2

C

C

H2

H2Cl

ClCl(actually both

steps at once)

••

••HOMO() LUMO(*)HOMO(p)

LUMO(p)

New LUMONew HOMO-2New

HOMO-1

NewHOMO

* F-CH3

It is very common for an “electrophile” (LUMO) adding to the HOMO of an alkene to come along with a HOMO that can react

with the * LUMO of the same alkene. This is the case in the previous example where the

LUMO is the * of Cl-Cl (or the vacant 2p orbital of Cl+) and the

HOMO is an unshared pair of Cl.

EthersHOMO :O

LUMO *CO

Alkyl Halides AlcoholsHOMO :XLUMO *CX

HOMO :OLUMO *OH

(or *CO)

Aldehydes / Ketones

R

R

O

-Y:

R R

O

Y

-

Addition of HY to C=O

H__Y

-Y:R R

OH

Y

HOMO :OLUMO *C=O

Imines BoranesLike C=OHOMO :NLUMO *

HOMO B-H

LUMO 2pB

Carboxylic Acids

Acidic because RCOO- has better HOMO-LUMO mixing

(resonance stabilization) than RCOOH.

Acid Derivatives

All have an X group attached to C=O that can leave as a reasonable anion.

R

X

O

-Y:

R X

O

Y

-

R

Y

O

X-

reverse or Substitution of Y for X

I think I have fixed the following frame from the lecture of

11/16/05 so that it works with other browsers.

[No one had told me of the problem until day before yesterday. Let me

know when something fails.]

CIP (R/S) Nomenclaturefor Stereogenic Centers

(S)inister (left)

COOH

COOH

OH

H

H

HO4

3

2

1

1

3

4

2

(2R,3R)-2,3-dihydroxybutanedioic

acid

rightturn

H

(R)ectus (right)

H

Jones Sec. 4.4 pp. 157-161

HO D

CH3

H

leftturn

HO CH3

D

H

14

2

3

CH3 CH3

HO HODHHD

Why Maxwell’s velocity distributions are different in

1, 2, and 3 Dimensions.

(a minor point for Chem 125)

James Clerk Maxwell

(1831-1879)

Distributionof Velocities

On the Motions and Collisions of perfectly elastic Spheres (1859)

to find: f(vx)

probability ofx-velocity between

vx and vx + d vx

vx

vz

vy

v

(Total velocity) v2 = vx2 + vy

2 + vz2

Assume vx , vy , vz are independent

(meaning that joint probability is a product)

g(vx2 + vy

2 + vz2) = f(vx) f(vy) f(vz)

ProductSum

g(vx2 + vy

2 + vz2) = c3 e-a (vx

2 + vx2 + vx

2)

f(vx) = c e-a vx2

f(v) = C v2 e-a v2

vx

vz

vy

v

Note that for a certain magnitude of v, the little dx dy dz box, in which we have reckoned probability, could be anywhere on the surface of a sphere of radius v. The area of this surface is proportional to v2.

f(v) = C v2 e-a v2

0.00

0

v

f(v)

1D2D

3D

MaxwellVelocity

Distribution