Chemistry Reference
In-Depth Information
8. Where possible, the leaving group (Y
) should be as hydrophilic as possible;
good candidates are Cl
and mesylate. Anionic leaving groups that are
particularly hydrophobic such as iodide and p-toluenesulfonate, tend to
form tighter ion pairs with the quat cation and slow down or stop the PTC
process.
Chemical processes related to or involving interfacial interactions such as those
introduced in this chapter present great opportunities for new and better pathways
for the transformation of raw materials into useful chemical products. They have
been utilized in nature since the origin of life, without understanding by humankind
for thousands of years, and by design for about a hundred. Economic, environmen-
tal, and intellectual driving forces will undoubtedly lead to their greater use in the
years to come.
PROBLEMS
6.1. Given the following chemical structures, predict the probable location of each
of the following compounds if solubilized in aqueous micellar solutions of (a)
sodium dodecyl sulfate, (b) n-hexadecyltrimethyl ammonium bromide, (c)
dodecylphenol(POE)
7
:
n-Hexadecane
n-Octanoic acid n-butyl lactate
Chlorobenzene
Methyl oleate
2,5-Di-t-butylhydroquinone
Di-n-butyl ether
Naphthalene
N,N-dimethylhexadecyl amine
Tetrahydrofuran
6.2. Which of the following surfactants would be expected to be most efficient at
solubilizing hexadecane: sodium n-nonylbenzene sulfonate, sodium hexa-
decylsulfate, benzyltrimethylammonium acetate, or SDS? For solubilizing
cholesterol?
6.3. A system of aqueous micelles of a nonionic POE surfactant is found to
solubilize an average of 2 molecules of a material per micelle at 25
C. If the
temperature of the system is raised to 50
C, would you expect the solubilizing
capacity per micelle to increase or decrease? Based on the information
provided, for the same total surfactant concentration, what can you say about
the total solubilizing capacity of the system at the two temperatures?
6.4. If an aqueous micellar solution of sodium tetradecylsulfate is employed to
solubilize a polar dye, would you expect the addition of dodecyl alcohol to
increase, decrease, or not affect the capacity of the system?
6.5. For the solubilization of high-molecular-weight hydrocarbons in anionic
micelles, would the addition of electrolyte be expected to increase, decrease,
or not affect the capacity of the system?
6.6. The base-catalyzed hydrolysis of esters is accelerated by the presence of
10
4
M nonylphenyl-POE
9
ether surfactant, unaffected by 10
4
M SDS, and
