Final Exam

Boiling Points:

  1. CH4
  2. NH3
  3. H2O

  1. -162° C
  2. -33° C
  3. 100° C

How many kcal/mole more stable is benzene due to resonance?
36 kcal/mole

How strong is the hydrogen bond?

 

5-6 kcal/mole

What are the bond strengths of:
  1. C=C (? + ?)
  2. C=C (? only)
  3. C—C 
  4. C—H
  5. H—H

  1. 146 kcal/mole
  2. 63 kcal/mole
  3. 83 kcal/mole
  4. 99 kcal/mole
  5. 104 kcal/mole

General formula for alkanes:
CnH2n+2
General formula for cycloalkanes:
CnH2n
R-Cl
alkyl chloride
R-OH
alcohol
[image]

carbonyl – can be either:

  • aldehyde
  • ketone

[image]
aldehyde
[image]
ketone
[image]
formaldehyde
[image]
amide
[image]
carboxyl/carboxylic acid
[image]
ester/carboxylic acid ester
[image]
nitrile
[image]
secondary (2°) amine
[image]
ether
Rotational energy barrier for C=N pi bond:
?18 kcal/mole
Rotational energy barrier O=O pi bond:
?5 kcal/mole
pKa of H2O:
15.7
pKa of hydronium ion (H3O+):
-1.7
pKa=?
-log(Ka)

Ka equation for following reaction of weak acid (HX):

 

HX + H2O – H3O+ + X

Ka = [H3O+] [X] ? [HX]

 

or:

Ka = [H3O+]2 ? [HX]

 

Electronegativities of following elements:

 

H          C          N          O          F

 

 

                        P           S          Cl

H          C          N          O          F

2.2       2.5       3.0        3.5        4.0

 

                        P           S          Cl

                       2.2        2.5        3.0

pKa of acetic acid: [image]
4.7
pKof ethanol: [image]
?16
pKa of chloroacetic acid: [image]
?2.9

pKa of methane:

 [image]

50-60

pKa of an alkene:

[image]

?44

pKa of a terminal alkyne:

 

R?C—H

?25
For EA, how many kcals/mole per order of magnitude?
1.35 kcal/mole

EA difference between eclipsed and staggered ethane:

[image]

2.9 kcal/mole

Difference in energy between gauche and anti-butane:

[image]

?0.8 kcal/mole

How much more stable is the chair confomer than the half-chair confomer of cyclohexane?

[image]

?10.9 kcal/mole

How much more stable is equitorial methyl-cyclohexane than axial-methylcyclohexane?

[image]

?1.8 kcal/mole

In what category do these belong? Name them:

[image]

Bicyclic compounds

  1. bicyclo [4.3.0] nonane (fused)
  2. bicyclo [3.2.1] octane (bridged)
  3. bicyclo [3.2.2] nonane (bridged)
  4. bicyclo [3.3.1] nonane (bridged)
  5. bicyclo [4.2.0] octane (fused)

Formula for number of possible enantiomers:

[image]

2n where n=total centers of chirality
[image]
sulfydryl group/thiol
Draw the intermediate of an SN2 reaction and indicate its hybridization state

[image]

sp2 hybridized

What are the relative rates of the following alkyl-halides for SN2 reactions?

  1. methyl halide (1°)
  2. ethyl halide (1°)
  3. isopropyl halide (2°)
  4. neopentyl halide (1° – special case)
  5. tertiary (3°) alkyl halide 

  1. 30
  2. 1
  3. 0.03
  4. 10-5
  5. 0

  1. ?G and
  2. Rate equation for reaction: 

 

CH3—Cl + OH > CH3—OH + Cl

  1. -24 kcal/mol
  2. rate = [CH3Cl] [OH]Ae?G/RT

Rank these oxygen containing compounds in order of decreasing nucleophilicity:

 

OH, H2O, RO, ROH, RCO2

RO>OH>RCO2>ROH>H2O

Rank these compounds in order of decreasing nucleophilicity:

 

HS, IOH, CN

HS>CN>I>OH

Rank these compounds in order of decreasing nucleophilicity:

 

CH3CO2, CH3OH, CH3O,CH3CO2H, CN

CN>CH3O>CH3CO2>CH3CO2H>CH3OH
What is the resultant stereochemistry from an SN1 reaction with a chiral starting material?
racemic mixture – 1:1 ratio of enantiomers
How much ring strain in cyclopropane?
?25 kcal/mole

What are the torsional energies of the following butane conformations:

  1. anti
  2. eclipsed II and VI
  3. eclipsed IV
  4. gauche 

 

              (1)   (2)   (4)    (3)

[image]

[image]
propyl group
[image]
isopropyl group
[image]
tert-butyl
[image]
sec-butyl
[image]
butyl group
[image]
phenyl group
[image]
benzyl group
What bond is the strongest as far as IR spectroscopy is concerned?
O—H

For ethene, what are the:

  1. hybridization state of carbons
  2. bond angles

  1. sp2  
  2.  

[image]

 

Definitions of:

  1. BrOnsted acid
  2. BrOnsted base

 

  1. proton (H+) donor
  2. proton (H+) acceptor

Definitions of:

  1. Lewis acid
  2. Lewis base

  1. electron pair acceptor
  2. electron pair donor

x

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