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Solvents are chemicals that dissolve the solutes in a formulation. These solutes might take the form of solids, liquids, or gases. Solvents are utilised to create a solution once the solute interacts with them.
Aqueous and Non-aqueous Solvents
Aqueous solutions contain liquid water as their solvent. Water molecules encircle and integrate the solute (dissolved) ions and molecules into the water’s network of links. Following that, the dissolved species get diffused throughout the water.
A non-aqueous solvent is not an organic chemical and is not water. Liquid ammonia, antimony trichloride, sulfuryl chloride, hydrogen fluoride, nitrogen tetroxide, pure sulphuric acid, sulfuryl chloride fluoride, phosphoryl chloride, bromine pentafluoride, and other inorganic acids are some of the most common examples of non-aqueous solvents.
Types of Non-aqueous Solvents
Non-aqueous solvents are utilised in non-aqueous titration. There are four types of non-aqueous solvents:
- Aprotic Solvents: These solvents act as catalysts and are chemically inert. These solvents can accelerate or reduce the reaction rate during the chemical process or reaction, depending on the situation. The most common aprotic solvents are chloroform and benzene, neither are acidic nor basic.
- Protogenic Solvents: These are naturally acidic. They can donate a proton and improve the strength of weak bases. Hydrochloric acid and sulphuric acid are examples of protogenic solvents.
- Protophilic Solvents: Natural photophilic solvents are basic and have a strong proton affinity. Liquid ammonia, amines, and ketone are examples of protophilic solvents.
- Amphiprotic Solvents: These are protogenic and protophilic in nature. Amphiprotic solvents have acidic and basic properties. They also take the proton and donate it—for example, water, alcohols, and weak organic acids.
Purpose of Non-Aqueous Solvents
Non-aqueous titrations are the most common titrimetric approach used in pharmacopoeial assays. They serve a dual purpose: they may be used to titrate weak acids and bases while also providing a solvent in which organic molecules can be dissolved.
Titration is the process of calculating the quantity of material A by adding measured increments of substance B, the titrant, with which it reacts until exact chemical equivalency is obtained (the equivalence point).
A simple, quick and cost-effective method was devised for determining loratadine (LOR) in pure and pharmaceutical dosage forms. The method uses acetous perchloric acid as a titrant and acetous crystal violet as an indicator in a non-aqueous titration.
The final titer data are subtracted from the blank to obtain the real amount of acetous perchloric acid equal to LOR. The approach was used to determine LOR in pure and pharmaceutical formulations successfully. The proposed method’s percentage recoveries ranged from 84.8 0.1 per cent to 100.9 0.1 per cent. The approach demonstrated acceptable precision and accuracy by determining LOR without significant interference in the presence of various excipients seen in commercial preparations.
Aqueous Solutions
Aqueous is a term used to describe a water-based system. Aqueous can also refer to a solution or mixture including water as the solvent. The chemical bonding type of a material determines whether or not it will form an aqueous solution.
When a material dissolves in water, the symbol (aq) is added to the chemical name. Many ionic chemicals and hydrophilic (water-loving) entities dissolve in water.
For example, table salt dissolves in the water. Hydrophobic, or water-averse, substances do not dissolve in water or produce aqueous solutions. There will be no dissociation if you mix oil and water.
Types of Aqueous Solutions
- Electrolyte Solutions: Solutions that conduct electricity are known as electrolyte solutions. Since salt’s dissociated ions can travel freely in a solution when it dissolves, they allow a charge to flow. When salt is mixed with a solvent like water, electrolyte solutions are created. An electrolyte is a salt or ionisable molecule that permits that solution to conduct electricity when dissolved in a solution.
- Strong and Weak Electrolytes: An electrolyte is a salt or ionisable molecule that permits a solution to conduct electricity. A charge can flow because a salt’s dissociated ions can travel freely in a solution when it dissolves. A strong electrolyte dissociates into its constituent ions in solution, whereas a weak electrolyte remains fundamentally undissociated. Weak electrolytes include acetic acid, which is also a weak acid.
- Nonelectrolyte Solutions: Nonelectrolytes are substances that do not ionise in water. As a result, nonelectrolyte-containing liquids do not conduct electricity. Covalent bonds, rather than ionic ones, typically hold nonelectrolytes together. Glucose or C6H12O6 is an example of a nonelectrolyte. Although glucose (sugar) dissolves quickly in water, it is classified as a nonelectrolyte because it does not break into ions in the solution and does not conduct electricity.
Conclusion
An aqueous solution has water as its solvent. The sign (aq) after a species name in a chemical equation indicates that it is in an aqueous solution. Non-aqueous solvents, on the other hand, are utilised in chemical research and industry for reactions that cannot be performed in aqueous solutions or that require a unique environment.
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