Chemical Properties and Major Uses of Resorcinol
Properties of Resorcinol
Physical Properties – It shows following physical properties –
It is white in color and solid at room temperature.
It is soluble in water, alcohol and ether.
Its molar mass is 110 g/mol.
It turns pink on exposure to air, light and iron.
It gives a faint benzene odor.
It is insoluble in chloroform and carbon disulfide.
Its melting point is 110℃.
Its boiling point is 277℃.
Its density is 1.28g/cm3.
Chemical Properties – It shows following chemical properties –
It reduces Fehling’s solution and ammoniacal silver solution.
Phthalic anhydride reaction with resorcinol –
Reaction of Resorcinol With Tert-amyl Alcohol –
Reaction of Resorcinol With Ethyl Acetoacetate –
Reaction of Resorcinol With Formaldehyde –
Production of Resorcinol
Resorcinol is prepared from benzene. It crystallizes from benzene as colorless needles. Production of it from benzene takes place through several steps. It is a classic sulfonate fusion process. In this, benzene is treated with sulfuric acid at 100℃ which gives mono sulfonic acid. Which is converted to m-disulfonic acid with 65% oleum at 85℃. Now m-benzenedisulfonate melts in alkaline medium (NaOH) at 300℃ which gives resorcinol and sodium sulfite. Reaction is given below –
As the above reaction shows one step can be reduced by reacting SO3 directly to benzene.
Applications of Resorcinol
Large scale production of resorcinol itself shows its high demand in the market and usefulness. Few applications of resorcinol are listed below –
It is used in acne treatment.
It is antiseptic and disinfectant so used in treatment of many chronic skin diseases such as eczema, psoriasis etc.
It is used in shampoo as an anti-dandruff agent.
Its 2% solution has been used in the treatment of hay fever and whooping cough.
It protects from UV -rays so used in sunscreens.
It is used in treatment of gastric ulcers.
It is used in many medicated soaps as well.
It is used in the production of diazo dyes, plasticizers and resins.
It is used as an analytical reagent for qualitative determination of ketoses.
It is used in explosive materials as well.
It is used in synthesis of raw materials for aerogel.
As it can withstand a wide range of temperatures So,
it is used in the automotive industry as well.
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FAQs on Resorcinol: Complete Guide for Chemistry Students
1. What exactly is resorcinol in chemistry?
Resorcinol is an organic compound that belongs to the family of phenols. Chemically, it is a dihydroxybenzene, which means it has a benzene ring with two hydroxyl (-OH) groups attached at the 1st and 3rd carbon positions. It is an isomer of catechol and hydroquinone.
2. What is the chemical formula and structure of resorcinol?
The chemical formula for resorcinol is C₆H₆O₂. Its structure features a six-carbon benzene ring with two hydroxyl groups (-OH) attached to the carbon atoms at positions 1 and 3. This specific arrangement is also known as meta-dihydroxybenzene.
3. What is the official IUPAC name for resorcinol?
The official IUPAC (International Union of Pure and Applied Chemistry) name for resorcinol is benzene-1,3-diol. This systematic name clearly describes its structure: a 'benzene' ring with two 'diol' (hydroxyl) groups located at the 1st and 3rd positions.
4. What are the most common uses of resorcinol in real-world applications?
Resorcinol has several important applications across different industries. Some key examples include:
- Adhesives: It is used to manufacture strong, waterproof adhesives known as resorcinol-formaldehyde resins, often used for bonding wood or reinforcing rubber in tires.
- Skincare: In low concentrations, it is used in topical treatments for acne and eczema due to its exfoliating and antiseptic properties.
- Dyes and Chemicals: It acts as a building block (an intermediate) in the synthesis of various dyes, plastics, and pharmaceuticals.
5. What does resorcinol look like, and what are its key physical properties?
In its pure form, resorcinol is a white, crystalline solid, often appearing as small needles or a powder. It is soluble in water and alcohol. A notable property is that it can slowly turn pink or reddish when exposed to light and air due to oxidation.
6. How is resorcinol different from its isomers, catechol and hydroquinone?
Resorcinol, catechol, and hydroquinone are all isomers with the same formula, C₆H₆O₂. The main difference lies in the position of the two hydroxyl (-OH) groups on the benzene ring:
- Resorcinol: The -OH groups are at positions 1 and 3 (meta-position).
- Catechol: The -OH groups are at positions 1 and 2 (ortho-position).
- Hydroquinone: The -OH groups are at positions 1 and 4 (para-position). This structural difference affects their physical properties, such as melting point, and their chemical reactivity.
7. Why is resorcinol more reactive than benzene in chemical reactions?
Resorcinol is more reactive than benzene because the two hydroxyl (-OH) groups are powerful activating groups. They donate electron density into the benzene ring through resonance, making the ring much more electron-rich. This increased electron density makes it more susceptible to attack by electrophiles, causing it to undergo electrophilic substitution reactions more readily than benzene.
8. How does resorcinol actually work in skincare products to treat acne?
In skincare, resorcinol functions as a keratolytic agent. This means it helps break down and shed the hard, outer layer of dead skin cells. By removing this layer, it helps to unclog pores and prevent the formation of pimples. It also possesses mild antiseptic qualities, which can help reduce acne-causing bacteria on the skin.
9. Is there a simple lab test to confirm if a compound is resorcinol?
Yes, a common qualitative test is the phthalein dye test. When resorcinol is heated with phthalic anhydride and a drop of concentrated sulphuric acid, it forms a specific dye. If this mixture is then added to a dilute sodium hydroxide (NaOH) solution, the appearance of a distinct green fluorescence confirms the presence of resorcinol.
10. Is resorcinol related to vitamins like Vitamin A?
No, resorcinol is not a vitamin and has no nutritional relationship to Vitamin A. Resorcinol is a simple phenolic compound (benzene-1,3-diol) used for its chemical properties. In contrast, vitamins like Vitamin A (retinol) are complex organic molecules that are essential nutrients required for biological processes in the body. They are chemically and functionally distinct.
