Sulfonation

Dr. Sajjad Ahmad

Assistant professor
UET (Lahore) FSD Campus
Part #1
• What is sulfonation
• Types of sulfonation
• Classification of sulfonates
• Procedures for preparing sulfonates
 Sulfonation
Sulfonation is the introduction of a sulfonic acid
group (–SO3H), or the corresponding salt or
sulfonyl halide group into an organic compound.

Types Of Sulfonation Include

1. Sulfochlorination
2. Halosulfonation (ClSO3H)
3. Sulfoxidation
4. Sulfoalkylation
5. Sulfoacylation
6. Sulfoarylation
 Classification of sulfonates

• Aliphatic and alicyclic

• Aromatic
• Hetrocyclic
• N-sulfonates
 Procedures for preparing
sulfonates
1. Treatment of an organic compound with
SO2
2. Treatment with a compound of SO2
3. Condensation and polymerization methods
4. Oxidation of an organic already containing
sulfur in a lower state of oxidation such as
RSH.
 Sulfation
• Involves the placement of the –OSO2OH group
on carbon, yielding an acid sulfate (ROSO2OH)
, or of the –SO4- group between two carbons,
forming the sulfate ROSO2OH.
• Sulfatoalkylation designates introduction of a
sulfated alkyl group into an organic compound
Classification of sulfates

Sulfated alkanes
Alcohol sulfates
Cyclic sulfates
Sulfated carbohydrates
Sulfated nitrogenous polysachrides
Sulfonating and sulfating agents
• Sulfur trioxide and compounds
1. Sulfur trioxide, oleum, concentrated sulfuric acid (SO3 plus
water)
2. Chlorosulfonic acid (SO3 plus HCl)
3. Sulfur trioxide adducts with organic compound
4. Sulfamic acid
• The sulfur dioxide group
1. Sulfurous acid, metallic sulfates
2. Sulfur dioxide with chlorine
3. Sulfur dioxide with oxygen
• Sulfoalkylating agent
1. Sulfomethylating agents
2. sulfoethylating agents
3. Miscellaneous alkylating agents
Chemical and physical factors in
sulfonation and sulfation
• When employing SO3 or its compound for
sulfonation and sulfation, important variables
determining the rate of reaction are
1. Concentration of SO3 in sulfonating agent
2. Chemical structure of organic compound
3. Time in relation to temperature and reagent
strength
4. Catalyst
5. Solvents
Concentration of SO3
• To carry sulfonation and sulfation, it is necessary
to maintain the SO3 concentration in the
sulfonating agent at a certain minimum level.
• SO3 itself employed
1. Initial stage of sulfonation is completed rapidly
2. When reacting with HC But sulfonic acid
produced react with SO3 to form complex
Sulfonating organic acid which is less reactive
than SO3
3. When reacting with Sulfonating Organic Acid
Initial reaction product is acyl sulfate
4. Next it is converted to sulfonate
Hydrates of SO3
• Hydrates of SO3 are usually the solution of SO3 in
water
• Water has a great affinity for SO3
• In this system it regarded as base which in
proportion to its concentration tend to neutralize the
acidic SO3
Procedure for completing
sulfonation
• Use of excess acid
• Physical removal of water
• Chemical removal of water
Chemical structure
• Aromatic hydrocarbons as a class are easily
sulfonated
• Substitution of hydrocarbon ring with hydroxal or
amino groups, or with successive alkyl groups,
increases the ease of sulfonation
• Halogen, nitro, carbonyl, and sulfonyl groups make
sulfonation more difficult
• Ortho para directing groups facilitate sulfonation,
while meta directing groups hinder sulfonation
Time-temperature-reagent
strength
• To attain maximum efficiency in comercial
sulfonation the reaction time must be reduced to
minimum compatable with product yield
• Reaction rate is approximately doubled by 10°C rise
in temp.
• Maximum reaction rate is achieved with stronger
reagent
Catalyst and sulfonation aids
• Changing orientation
1. The addition of mercury changes the orientation in a
number of aromatic sulfonation reactions
2. The form of mercury employed is immaterial
3. An organic mercurial intermediate is formed
4. Catalytic effect functions for disulfonation
5. Mercury is utilized only when using oleum or SO3 as
sulfonating agent.
6. Mercury effects the orientation of benzoic acid, phthalic
anhydride,naphthol, nitrobenzene.etc
7. Mercury is also utilized in some cases to increase yield in
sulfonation but without changing orientation
Catalyst
• Facilitating reaction
1. The addition of catalyst sometimes allows the use
of lower temperatures, improve yield,
acceleration reaction.
• Inhibiting side reactions
1. sulfone formation in case of aromatic sulfonation
can be avoided by adding acetic acid
Solvents

• Excess acid
• Chlorinated solvents
• Liquid SO2
• Aqueous solvents
• Miscellaneous solvents
• Solvent stability
Kinetics of sulfonation
• Aromatic sulfonation is a eelectrophilic substitution reaction
• Sulfonation is a reversible process
• Reaction temperature in certain cases have an important
influence on position of entering group
• Sulfur tri oxide has a tendency to form complex with
sulfonic acid
• With sulfuric acid formation of water slows the reaction
• With sulfur high speed of reaction is a problem
• We have different rate equations with different sulfonating
agents
Mechanism of reaction
• Eelectrophilic substitution
Aromatic sulfonation
• Without sulfur trioxide
• Intermediate compound is electrically neutral.
Thermodynamics
• Heats effects encountered in sulfonation are of great
importance.
• Depending upon the reaction involved and upon
how it is conducted, net effect may vary widely
from highly exothermic over a short period of time
to endothermic over a long period
• Some reactions are exhothermic in initial stage but
endothermic in final stage.
With SO3 and its compounds
• With SO3 and its compounds it is convenient to
calculate the net heat effect in any particular
sulfonation by using SO3 vapour as reference
point reasons are
1. More heat is evolved in sulfonation with this
reagent then with any other group
2. All th compound of SO3 used as sulfonating
agents can be made from it by direct exothermic
reaction with the material forming the compound
Heat of sulfonation
• Net heat evolved can be calculated from the
following equation
∆Hc = ∆Hv - ∆HD
∆Hc = heat of sulfonation with compound of SO3
being used as sulfonating Agent
∆Hv = heat of sulfonation with SO3 vapor
(exothermic)
∆HD = heat of dissociation of sulfonating agent into
SO3 vapor and compounding reagent (endothermic)
Desulfonation reactions
• Aromatic sulfonates are hydrolytically desulfonated by
heating in aqueous acid medium
• This reverse reaction generally proceeds in rapidly and in
good yield especially in the presence of mineral acid which
accelerates the reaction catalytically.
• It is proportional to hydrogen ion activity of solution.
• For each 10ºC rise in temperature the reaction velocity of
hydrolysis increases 2.5-3.5 times and same with molar
increase in acid concentration.
• With increase ring methylation desulfonation temperature
lowers.
Desulfonation
• Sulfonation followed by desulfonation has been
used to separate mixtures of aromatic compounds
not easily separable by sulfonation.
• Desulfonation is a tool in studying the chemical
structure of commercial sulfonated petroleum
fractions from lubricating oil range.
• Sulfonation-desulfonation is a useful tool for
preparing ortho isomer derivative of benzene.
• Useful in raw material and waste recovery
Working-up procedures
• There are different factors that make the final
product separation a time consuming process.
1. Presence of excess acid
2. Unreacted starting material
3. Occurrence of side reactions
• Some commercial sulfonation apply
stoichiometric amounts of reagents and product
can be used after neutralization.
• In some cases even with excess acid more
seperation is not required
Separation processes
Dilution with water
• This method is often applied when using excess acid or oleum
and yield free sulfonic acid
• Its use is based on the knowledge that many sulfonic acid are
relatively insoluble in sulfuric acid of intermediate strength
obtainable by suitable dilution of reaction mixture with water
• Applied for th separation of
1. Hydrocarbon sulfonic acids
2. Disulfonic acid of anthraquinone
3. Sulfonated aromatic amines
4. Sulfonated fatty oils
5. Aromatic sulfonyl chlorides
Separation processes
• Salting out
• The method yields the sulfonate salt by the addition of
aqueous NaCl to the acid reaction mixture
• The desired sulfonate salt is usually only slightly soluble
in the dilute acid medium and often crystallizes from it in
good yield.it is used in seperation of
1. Sulfonate dye intermediates
2. Sulfonated fatty oils
3. Efficiently employed to obtain highly water soluble
sulfonate salts
Separation processes
Neutralization with lime
• The procedure involves treatment of diluted reaction mixture
with Ca(OH)2 or CaCO3 to convert excess sulfuric acid to
insoluble calcium sulfate and the sulfonic acid to calcium
sulfonate.
• Treatment of filtrate with sodium carbonate or sulfate yields
insoluble calcium carbonate or sulfate
• The filtrate comprises the desired sodium sulfonate
• Use for the isolation of any sulfonate yielding a soluble
calcium salt.
Industrial equipment and
techniques
Material of construction
• Cast iron is resistant to action of sulfuric acid
• Lined steel vessels combine low cost and high
strength with good corrosion resistance
Commercial sulfonation
methods
• Batch process
• Continuous process
Batch processing
• Sulfonation is conducted in
autoclaves of standard type
• Major feature of
consideration are heat
transfer and agitation
• Depending upon conditions
equipment maay be of cast
iron,glass lineed, lead lined
Batch processing
• Ball-mill sulfonator,operable under vacuum with
hot air heating, used with solid, doughy or viscous
masses.
• Plastic coated steal towers are used.
Heating and cooling
• Sometimes direct gas fire is used for heating
• Steam is most commonly employed
• Steam under pressure is used in jackets capable of
bearing 10atm pressure
• In some cases cooling is required which could be
done by using brine.
• By spraying water outside of kettle.
• By circulating through heat exchanger
Continuous process
• Continuous process in sulfonation is usually
preferable in dye intermediates which are prepared
in relatively small amount from expensive raw
materials
Aliphatic sulfonation
• Sulfomethylation of aniline
1. Aniline is reacted with aqueous sodium
hydroxymethanesulfonate.
2. Aqueous sodium bisulfite is charged to a brick lined vessel
equiped with a blde agitator and copper coil for heating and
cooling.
3. Formaldehyde is then added with agitation followed by heating
for half an hour.
4. After cooling to 25ºC aniline is added and temperature is
maintaind to 25ºC for 3 hours.followed by heating to 35ºC for
one hour.
5. Tests are performed to check completion.salting out is done to
get sulfonate.
6. Product is washed and filtered off.
Addition of sodium bisulfite to
maleic acid ester
• Di maleate and 95% and ethanol are charged to an
enameled jacketed kettle provided with moderate agitation
and distillation take off.
• Aqueous sodium hydroxide is then added to neutralize
toluene sulfonic acid catalyst in the crude ester.
• Aqueous bi sulfite is then added and the mixture is heated
to 100ºC with slow agitation.it is held at this temp for 12
hours
• The mix is cooled to 60ºC and the distillation take off is
connected for the removal of alcohol solvent begins at 80ºC
• Distillation continued for 7 hours aat 91ºC to remove 75%
alcohol.
• Solution is then cooled and packed
Sulfoethylation of oleic acid
• Oleoyl chloride is heated with sodium 2-
hydroxyethanesulfonate.
• Solid 2-hydroxyethanesulfonateis shoveled into a
homogeneous lead lined condensation kettle.
• Heating and stirring begin with oleoyl chloride addition.
• The mixture is stirred for 15 min after reaching 100ºC.
• When the reaction is vigorous and HCl evolved.
• Temperature rises to 110ºC.
• Finally powdered product is attained
• Neutralize with sodium carbonate
Monosulfonation of benzene
• Benzene can be monosulfonated by partial pressure
distillation method
• Sulfuric acid is pumped from storage
• Liquid benzene from storage is pumped to direct
vaporizer superheater and then to sulfonator and
sulfonation tower
• Reaction time is 1.5 hours
• Temperature is 180ºC
Sulfonation of dodecylbenzene
• The hydrocrbon is pumped into the glass lined sulfonation kettle
equiped with turbo type mixer and external heat exchanger.
• Mixer is turned on and 20% oleum is added as fast as possible,
not exceeding a temperature of 30ºC.
• Reaction time is 1.5-2.0 hours.
• At the end spentacid has a strength of 98.2% and is mixed with
sulfonic acid
• Water is added for layer seperation
• Upper laayer of sulfonic acid is neutralized by adding aqueous
soda
• Approximately 90% of the hydrocarbonis sulfonated.
Sulfonation of Benzene
• Benzene can be sulfonated by;
• Batch process
• Continuous process
• Batch time is more as compared to residence time in
continuous reactor.
Batch process for monosulfonation of
benzene
• Reaction time:14 hrs
• Temperature:160-180oC
• Acid strength:90-92%
• Jacketed cast iron sulfonation kettle is used
• Agitation done at 80rpm
Monosulfonation of benzene by continuous
process

• Sulfuric acid is pumped from storage

• Liquid benzene from storage is pumped to direct
vaporizer super heater and then to sulfonator and
sulfonation tower
• Reaction time is 1.5 hours
• Temperature is 180ºC
 Batch process for monosulfonation of benzene
Recycled
benzene
Benzene Benzene
feed line supply tank

Gaug
e
Cooling
Jacket coil

External oil Perforated

heating Condensed
distributor
mechanism liquor tank
Monosulfonation of benzene Pressure
regulator
Meter

Benzene+ Condense
water r
vap.
Sulfon
-ator
Separato
Benzene vap. r Benzene
water

Sulfonatio
n tower
Direct vaporizer Neutralizing
super heater drier
Product
meter
Pump

Liq.Benzene
Sulfuric acid tank storage tanks
Anthraquinone 1-sulfonate
Raw materials
• quinone
• oleum
Catalyst
Mercury sulfate
Sulfonator temp. 50-60oC
Reaction time in sulfonator:30 min
 Storage for rotary
Wash water filter
Mixe
storage
r
Filter for
recovered
anthraquinone Rotary filter

Storage
AQ mixer for
dryer 35%K-salt
Conc. KCl slurry
soln.

Neutral
mixer

Storage

Sulfonat
or Filtrate 85oC
Pptator
receivers
Anthraquinone for K-salt
80oC
crystallizer