程序代写案例-CHEM 251

Organic Chemistry I – CHEM 251
O
NH2
OHC5H12
C4H9Br
C3H6
C3H4
(2) (3) (3)
(4)
(2)
(3)(8)
at least
(22
)
at least
(26)
Problem Set #1

[1] Draw the direction of the dipole for each bond highlighted in red. Some
highlighted bonds may not have a dipole. Fundamental



[2] Draw the direction of the net dipole for each of the following molecules. Some
molecules may not have a net dipole. Fundamental-medium




[3] Convert the following Lewis structures to their correct skeletal structures or vice
versa (skeletal structures to their correct Lewis structures). Fundamental




[4] Draw all constitutional isomers of the following molecules or molecular formula.
The total number of constitutional isomers for each compound is given in
parenthesis.

Fundamental:


Medium:


Very advanced:
(see if you can find 10 of each)
H
H
H
H
H
H
H
H
H
H
H
H O C O H
O
H
H Br
H3C
S
CH3
O
H3C
H2
C
C
H2
CH3I Cl
H
H
H
H
H
H O C O H
O
H H3C
S
CH3
O
H3C
H2
C
C
H2
CH3
O
OH N H
H
Br Br
C
O
C
H
H H
H
Br
O C C N H
H
H
H
H
H
H O
O
C C
H
H
H
C
CH
H
H H
H


Organic Chemistry I – CHEM 251
[12] The acid-base reactions of isopropanol and of acetone with water are shown
below (the acidic hydrogen atom is highlighted in red). Medium–advanced



Explain why isopropanol is 100x more acidic than acetone even though the
conjugate base of acetone is resonance stabilized while the conjugate base of
isopropanol is not.




[13] Squaric acid is a strong acid with pKa of 1.2. Draw the Lewis structure of the
conjugate base of squaric acid and use proper curved arrow notation to show
how its negative charge is shared by two oxygen atoms. Medium







[14] (i) Draw the Lewis structure of CH3NO2 showing all lone pairs and formal
charges.
(ii) Use curved arrow notation to show the acid-base reaction between CH3NO2
(pKa = 11) and water (pKa = 15.7).
(iii) Draw all resonance contributors of the conjugate base of CH3NO2. Label
which are major and which are minor contributors.
All medium








H3C
O
CH3
+ H O H H3C
O
CH2
+ H O H
H
H3C
OH
CH3
+ H O H H3C
O
CH3
+ H O H
H
isopropanol
pKa = 17
acetone
pKa = 19
O
O
OH
OH
Organic Chemistry I – CHEM 251
[15] (i) Use proper curved arrow notation to indicate the flow of electrons for the
following acid-base reactions and give the structures of the products. In each pair
of reactants the base should be easy to identify, though you will have to determine
which proton is the most acidic. Medium


(ii) Predict whether the equilibrium lies to the right (favoring products) or the left
(favoring products). The pKa values in the box will be helpful. Medium



























H H
O O
O
O
N
H
HOCH3 NH3
pKa 269 25.6 3615.2 36
Molecule
H H NH2
H H OCH3
O O
OCH3
O
O
N
O
O
OCH3
+
+
+
+
+
a)
b)
c)
d)
e)


























































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