216
transformations into various castor oil-based products. Castor oil-based products
are produced entirely environmentally friendly, biodegradable, and sustainable.
6 Castor Oil Products Significant Applications in Industries
Researchers are now emphasizing on the edible oils as the industrial raw materials
in the area of research. The using of edible oils as a raw material for chemical reactions is related to major environmental issues, the price of vegetable oil has increased
significantly, which inevitably influence the economic feasibility of edible-oil-based
goods. Consequently, the collection of edible vegetable oils cannot be deemed a
potential feedstock to a different industrial reaction. The production of industrials
chemical products made from non-edible oils is one possible way to get the better
control on such limitations. In this case of castor oil consisting of ricinoleic acid
around 90% and small quantities of oleic and palmitic acids, many non-edible oils
having higher in unsaturated oleic acid and lower in saturated palmitic acid. Castor
oil can therefore distinguish between other edible and non-edible oils, making it the
raw materials of greatest interest for the industries.
6.1 Dehydration
Iodine content in the castor oil is low and is thus referred to as a non-drying oil.
Although, it is non-drying when its dehydration gives semi-drying or drying oil.
Ricinoleic acid dehydration is a catalyzed acid reaction that eliminates the hydroxyl
group and forms a new double bond. Dehydration is typically done at a temperature
around 250 °C using most commonly employed catalysts such as concentrated sulfuric acid, sodium bisulfate, phosphoric acid, phthalic anhydride, and acid-activated
clay are most widely used under inert atmosphere or vacuum [3, 20–24].
This mechanism, the hydroxonium is developed by electrophilic attack by a proton against the unshared electron pairs of the carbon-12 hydroxyl group, and the
carbonium ion is generate by a loss of water, and ejection of a proton from either
carbon-11 or carbon-13 [25–27]. Since dehydrated castor oil commonly has a ratio
of 4:1 to 3:1 between nonconjugated and conjugated dienoic acid,it is easier to
remove hydrogen from the 13-carbon atom than in an 11-carbon atom.
As shown in Fig. 3, ricinoleic acid dehydration requires the elimination of the
hydroxyl group and one of its α hydrogen presents on one of the carbon-connected
hydroxyl group forming conjugated and nonconjugated linoleic acids. Typically
conjugated acid is polymerized and other anti-polymerizing agents such as sodium
sulfite or zinc chloride, or aluminum chloride [28]. Many potential side reactions
with estolide are developed during the dehydration of ricinoleic due to heat acceleration. Dehydrated castor oil-based protective coating, varnishes, lubricants, soaps,
paints, inks, alkyd resins system provide properties like quick-drying, durability,
chemical tolerance, metals adhesion, high gross and water quality [1, 4, 29].
S. Dhanuskar et al.
transformations into various castor oil-based products. Castor oil-based products
are produced entirely environmentally friendly, biodegradable, and sustainable.
6 Castor Oil Products Significant Applications in Industries
Researchers are now emphasizing on the edible oils as the industrial raw materials
in the area of research. The using of edible oils as a raw material for chemical reactions is related to major environmental issues, the price of vegetable oil has increased
significantly, which inevitably influence the economic feasibility of edible-oil-based
goods. Consequently, the collection of edible vegetable oils cannot be deemed a
potential feedstock to a different industrial reaction. The production of industrials
chemical products made from non-edible oils is one possible way to get the better
control on such limitations. In this case of castor oil consisting of ricinoleic acid
around 90% and small quantities of oleic and palmitic acids, many non-edible oils
having higher in unsaturated oleic acid and lower in saturated palmitic acid. Castor
oil can therefore distinguish between other edible and non-edible oils, making it the
raw materials of greatest interest for the industries.
6.1 Dehydration
Iodine content in the castor oil is low and is thus referred to as a non-drying oil.
Although, it is non-drying when its dehydration gives semi-drying or drying oil.
Ricinoleic acid dehydration is a catalyzed acid reaction that eliminates the hydroxyl
group and forms a new double bond. Dehydration is typically done at a temperature
around 250 °C using most commonly employed catalysts such as concentrated sulfuric acid, sodium bisulfate, phosphoric acid, phthalic anhydride, and acid-activated
clay are most widely used under inert atmosphere or vacuum [3, 20–24].
This mechanism, the hydroxonium is developed by electrophilic attack by a proton against the unshared electron pairs of the carbon-12 hydroxyl group, and the
carbonium ion is generate by a loss of water, and ejection of a proton from either
carbon-11 or carbon-13 [25–27]. Since dehydrated castor oil commonly has a ratio
of 4:1 to 3:1 between nonconjugated and conjugated dienoic acid,it is easier to
remove hydrogen from the 13-carbon atom than in an 11-carbon atom.
As shown in Fig. 3, ricinoleic acid dehydration requires the elimination of the
hydroxyl group and one of its α hydrogen presents on one of the carbon-connected
hydroxyl group forming conjugated and nonconjugated linoleic acids. Typically
conjugated acid is polymerized and other anti-polymerizing agents such as sodium
sulfite or zinc chloride, or aluminum chloride [28]. Many potential side reactions
with estolide are developed during the dehydration of ricinoleic due to heat acceleration. Dehydrated castor oil-based protective coating, varnishes, lubricants, soaps,
paints, inks, alkyd resins system provide properties like quick-drying, durability,
chemical tolerance, metals adhesion, high gross and water quality [1, 4, 29].
S. Dhanuskar et al.