Phthalic anhydride (C6H4(CO)2O) is a chemical compound used in the production of plastics, resins, and dyes. It is known for its strong odor and corrosive properties.
| IUPAC Name | 1,3-dioxoisoindoline-5-carboxylic acid |
| Molecular Formula | C8H4O3 |
| CAS Number | 85-44-9 |
| Synonyms | Phthalic acid anhydride, 1,2-benzenedicarboxylic anhydride, 1,3-isobenzofurandione |
| InChI | InChI=1S/C8H4O3/c9-7-5-3-1-2-4-6(5)8(10)11-7/h1-4H |
Phthalic Anhydride Properties
Phthalic Anhydride Formula
The formula of phthalic anhydride is C8H4O3. It consists of eight carbon atoms, four hydrogen atoms, and three oxygen atoms. The molecular formula represents the composition of the compound.
Phthalic Anhydride Molar Mass
The molar mass of phthalic anhydride is calculated by summing the atomic masses of its constituent atoms. It is approximately 148.12 grams per mole. Molar mass helps in determining the quantity of the substance in a given sample.
Phthalic Anhydride Boiling Point
C6H4(CO)2O has a boiling point of around 295 degrees Celsius. This temperature is the point at which the compound changes from a liquid to a gas phase when heated. The boiling point is an important characteristic for various applications.
Phthalic Anhydride Melting Point
The melting point of C6H4(CO)2O is about 131 degrees Celsius. It represents the temperature at which the compound transitions from a solid to a liquid state. The melting point is essential for handling and processing the substance.
Phthalic Anhydride Density g/mL
C6H4(CO)2O has a density of approximately 1.53 grams per milliliter. Density is a measure of how much mass is packed within a given volume of a substance. It aids in determining the substance’s physical properties.
Phthalic Anhydride Molecular Weight
The molecular weight of C6H4(CO)2O is approximately 148.12 grams per mole. It is the sum of the atomic weights of all the atoms in a molecule. Molecular weight is crucial for various calculations and conversions.
Phthalic Anhydride Structure
C6H4(CO)2O has a cyclic structure composed of two benzene rings connected by a carbon-carbon double bond. It possesses two carbonyl groups (-C=O) attached to adjacent carbon atoms. The structure influences its reactivity and chemical properties.
Phthalic Anhydride Solubility
C6H4(CO)2O is sparingly soluble in water, but it dissolves readily in organic solvents such as ethanol, acetone, and benzene. Solubility is the ability of a substance to dissolve in a particular solvent, affecting its application and handling.
| Appearance | White crystalline solid |
| Specific Gravity | 1.53 g/cm³ |
| Color | Colorless |
| Odor | Strong, pungent |
| Molar Mass | 148.12 g/mol |
| Density | 1.53 g/mL |
| Melting Point | 131 °C |
| Boiling Point | 295 °C |
| Flash Point | 151 °C |
| Water Solubility | 0.2 g/100 mL at 20 °C |
| Solubility | Soluble in organic solvents |
| Vapour Pressure | 0.07 mmHg at 25 °C |
| Vapour Density | 5.1 (air = 1) |
| pKa | 2.82 |
| pH | Not applicable |
Phthalic Anhydride Safety and Hazards
C6H4(CO)2O poses certain safety hazards and should be handled with care. It is considered corrosive to the skin, eyes, and respiratory system. Direct contact can cause irritation, burns, and allergic reactions. Adequate protective measures, such as gloves, goggles, and respiratory protection, should be used when working with the compound. In case of ingestion or inhalation, immediate medical attention is necessary. It is crucial to avoid release into the environment and dispose of it properly. C6H4(CO)2O should be stored in a cool, well-ventilated area away from sources of ignition. Safety data sheets and proper training should be consulted before handling the substance.
| Hazard Symbols | Corrosive (C), Harmful (Xn) |
| Safety Description | Avoid contact with skin and eyes. Use personal protective equipment. Handle in well-ventilated areas. Dispose of properly. |
| UN IDs | UN 2214 |
| HS Code | 29173500 |
| Hazard Class | 8 (Corrosive substances) |
| Packing Group | III |
| Toxicity | Harmful if swallowed or inhaled. Corrosive to skin and eyes. Can cause allergic reactions. |
Phthalic Anhydride Synthesis Methods
There are several methods to synthesize C6H4(CO)2O.
In the o-xylene oxidation process, vaporized o-xylene mixes with air or oxygen and undergoes catalytic oxidation in the presence of a suitable catalyst like vanadium pentoxide or metal phthalocyanine complexes. The reaction produces a mixture of C6H4(CO)2O and other by-products. Distillation purifies the mixture to obtain pure C6H4(CO)2O.
The synthesis of C6H4(CO)2O from ortho-xylene involves the vapor-phase oxidation of ortho-xylene using a supported catalyst, such as a vanadium pentoxide catalyst supported on a silica or alumina substrate. The reaction is carried out at elevated temperatures, and the resulting C6H4(CO)2O is collected and purified.
The catalytic oxidation of naphthalene produces C6H4(CO)2O along with carbon dioxide as a by-product. The reaction occurs at high temperatures in the presence of a catalyst like vanadium pentoxide.
C6H4(CO)2O obtained through these industrial synthesis methods serves as a vital intermediate for producing various chemicals, including plasticizers, polyester resins, and dyes. Controlling reaction conditions and purification steps carefully ensures a high yield and quality of C6H4(CO)2O.
Phthalic Anhydride Uses
C6H4(CO)2O finds numerous applications across various industries due to its versatile properties. Here are some key uses of C6H4(CO)2O:
- C6H4(CO)2O plays a crucial role in the production of plasticizers, such as diethyl phthalate and dioctyl phthalate, which enhance the flexibility and durability of plastics for a wide range of applications.
- Manufacturers utilize C6H4(CO)2O in the production of polyester resins, commonly used in fiberglass-reinforced plastics, coatings, adhesives, and laminates.
- It serves as a vital precursor in the synthesis of dyes and pigments, which find extensive use in textiles, printing inks, and paints.
- Industries incorporate C6H4(CO)2O into flame retardant formulations to enhance fire resistance in applications like electrical and electronic devices, textiles, and construction materials.
- C6H4(CO)2O serves as a crucial building block for producing herbicides and insecticides, which assist in controlling unwanted plants and pests in agricultural and horticultural practices.
- Alkyd resins, synthesized with the aid of C6H4(CO)2O, play a vital role in formulating paints, varnishes, and coatings, offering exceptional adhesion, gloss, and durability.
- It serves as a crucial intermediate for the synthesis of pharmaceutical compounds and active ingredients, contributing to the production of various pharmaceutical products.
The diverse applications of C6H4(CO)2O highlight its significance in various industries, contributing to the development of numerous everyday products and materials.
Questions:
Q: What is phthalic anhydride?
A: C6H4(CO)2O is a chemical compound used in the production of plastics, resins, dyes, and various other industrial applications.
Q: How to make phthalic anhydride?
A: C6H4(CO)2O is typically synthesized through the oxidation of o-xylene or naphthalene, using suitable catalysts and purification methods.
Q: What is phthalic anhydride in?
A: C6H4(CO)2O is used in the production of plasticizers, polyester resins, dyes, pigments, flame retardants, herbicides, insecticides, alkyd resins, and pharmaceutical intermediates.
Q: Is phthalic anhydride stable?
A: C6H4(CO)2O is relatively stable under normal conditions, but it can react with water, alcohols, and amines, and may undergo hydrolysis or form corrosive solutions.
Q: What is the molecular formula of phthalic anhydride?
A: The molecular formula of phthalic anhydride is C8H4O3.
Q: What companies produce phthalic anhydride?
A: Companies such as BASF, ExxonMobil, LANXESS, and UPC Group are known producers of C6H4(CO)2O.
Q: What is phthalic anhydride in a condensation polymer?
A: C6H4(CO)2O is used in the production of condensation polymers like polyesters, where it acts as a building block in the polymerization process.
Q: Is phthalic anhydride a solid?
A: Yes, C6H4(CO)2O is a white crystalline solid at room temperature.