Exercise 5 : - Acid-Base Reactions

1. Camphor is terpene which has many varied uses such as a plasticizer and in fireworks. Even though it is a naturally occurring compound, the high demand for this compound requires an additional synthetic source. Camphene is a readily available terpene and is used in the synthesis. The first step in the reaction involves treatment of camphene with an acetic acid/sulfuric acid mixture.

Write an equation for the first step in this synthetic sequence.

2. The following table lists pK_a values for a selection of acids in aqueous solution:

Acid	pKa	Acid	pKa	Acid	pKa
HI	-10	CH3OH2^+	-2,5	CH3OH	16
H2SO4	-9	H3O^+	-1.74	(CH3)2C=O	19.2
HBr	-9	CH3CO2H	4.75	HC≡CH	25
HCl	-7	NH4^+	9.2	NH3	38
(CH3)2OH^+	-3.8	C6H5OH	9.9	H2C=CH2	44
(CH3)2C=OH^+	-2.9	CH3NH3^+	10.6	C2H6	50

a. Will dimethyl ether, (CH₃)₂O, dissolve in concentrated sulfuric acid, H₂SO₄? Explain your answer.

Yes. (CH₃)₂OH⁺ (pK_a = -3.8) is a weaker acid than H₂SO₄ (pK_a = -9)

b. Will dimethyl ether, (CH₃)₂O, dissolve in acetic acid, CH₃CO₂H? Explain your answer.

No. (CH₃)₂OH⁺ (pK_a = -3.8) is a stronger acid than CH₃CO₂H (pK_a = 4.75)

3. Arrange the following compounds in order of decreasing acidity:

a.

b.

c.