Linear Alkylbenzene Sulfonic
Acid, also known as LABSA or LAS has a chemical formula of CH3(CH2)11C6H4SO3H.
LABSA exist as a brown liquid that is soluble in water and non-volatile. The
properties of LABSA vary in physical and chemical properties depending on the
length of the alkyl chain. It is also bio-degradable and hence easily
distinguished from alkylbenzene sulfonate (ABS) by its linear, straight chain
The commercial method of
manufacturing LABSA is by sulfonating linear alkylbenzene (LAB) with
either oleum (10-25% sulfur trioxide [SO3] in sulfuric acid) or an
SO3-air mixture. The major product is para-alkylbenzene sulfonic acid. The
reaction temperature has to be controlled during the addition of acid and the
reaction goes into completion after 30 to 45 minutes. Too high temperature and
reaction time and cause an undesirable dark-colored product.
Sulphuric acid (H2SO4)
is preferred over use of sulphur trioxide due to cheaper SO3 and
equipment cost. Reaction of pure SO3 it too aggressive an
electrophilic reagent and forms a black char on contact due to the rapid
exothermic reaction. As a result, cooling is required as high temperatures can
promote formation of by-products.Therefore, H2SO4 and
oleum are more commonly used for sulfonation of alkyl benzene and sulphate
fatty alcohols for heavy duty detergents. Water is formed in the reaction and
hence dilutes the oleum and H2SO4. Sulfonation reaction
stops when the concentration of H2SO4
drops by 90%.
Linear Alkyl Benzene Sulphonic
Acid (LABSA) is the most commonly used synthetic surfactant due to its low cost
and effectiveness. LABSA is an anionic surfactant widely used in a wide range
of Domestic Detergents Powder and dish wash cleaner as an emulsifier, wetting
agent due to its high solubility in water for foaming and low salt content. It
lowers the surface tension of water, allowing stains to loosen and release from
fabrics and surfaces.
LABSA is used widely in
agriculture industry. It is used in pesticides to enhance the quality of the
spray and produce better crop.
LABSA is used as a degreaser
of plating and leather making industry as well as a deinking agent in the paper