Maleic acid is an organic compound with the formula C4H4O4. It is a white crystalline solid used in the production of polymers, adhesives, and food additives.
| IUPAC Name | 2,3-dihydroxybutanedioic acid |
| Molecular Formula | C₄H₄O₄ |
| CAS Number | 110-16-7 |
| Synonyms | cis-Butenedioic acid, cis-1,2-Ethylenedicarboxylic acid, Toxilic acid |
| InChI | InChI=1S/C4H4O4/c5-3(6)1-2-4(7)8/h1-2H,(H,5,6)(H,7,8) |
Maleic Acid Properties
Maleic Acid Formula
The formula of butenedioic acid is C4H4O4. It consists of four carbon atoms, four hydrogen atoms, and four oxygen atoms. The formula represents the exact number and types of atoms present in one molecule of butenedioic acid.
Maleic Acid Molar Mass
The molar mass of butenedioic acid is calculated by adding up the atomic masses of all the atoms in its formula. Butenedioic acid has a molar mass of approximately 116.07 grams per mole. This value helps in determining the amount of butenedioic acid in a given quantity, using the concept of moles.
Maleic Acid Boiling Point
Butenedioic acid has a boiling point of around 160-162 degrees Celsius. This temperature indicates the point at which butenedioic acid changes from a liquid to a gaseous state under standard atmospheric pressure.
Maleic Acid Melting Point
The melting point of butenedioic acid is about 139-140 degrees Celsius. It signifies the temperature at which butenedioic acid transitions from a solid to a liquid form. This characteristic can be useful in various applications and processes involving butenedioic acid.
Maleic Acid Density g/mL
Butenedioic acid has a density of approximately 1.59 grams per milliliter. Density measures the mass of a substance per unit volume. The density of butenedioic acid determines its behavior in different physical and chemical processes, such as mixing with other substances or separating from them.
Maleic Acid Molecular Weight
The molecular weight of butenedioic acid is 116.07 grams per mole. It is the sum of the atomic weights of all the atoms in a molecule of butenedioic acid. Molecular weight is essential in various calculations, such as determining the concentration or the amount of butenedioic acid in a solution.
Maleic Acid Structure
Butenedioic acid has a structure consisting of two carboxyl groups (COOH) attached to a double-bonded carbon-carbon (C=C) framework. This arrangement gives butenedioic acid its characteristic properties and reactivity. The structure plays a crucial role in understanding its behavior in chemical reactions and interactions with other compounds.
Maleic Acid Solubility
Butenedioic acid is highly soluble in water, with a solubility of approximately 633 grams per liter at 20 degrees Celsius. This high solubility makes butenedioic acid readily dissolvable in aqueous solutions and enables its use in various applications, such as in the production of polymers and pharmaceuticals.
| Appearance | White crystalline solid |
| Specific Gravity | 1.59 g/mL |
| Color | Colorless |
| Odor | Odorless |
| Molar Mass | 116.07 g/mol |
| Density | 1.59 g/mL |
| Melting Point | 139-140 °C |
| Boiling Point | 160-162 °C |
| Flash Point | Not applicable |
| Water Solubility | Highly soluble |
| Solubility | It is highly soluble in polar solvents such as water and alcohol |
| Vapour Pressure | Not available |
| Vapour Density | Not available |
| pKa | 1.92 |
| pH | ~1-2 |
Maleic Acid Safety and Hazards
Butenedioic acid poses certain safety considerations and hazards. It can cause irritation to the skin, eyes, and respiratory system upon contact or inhalation. It is advisable to wear protective equipment, such as gloves and goggles, when handling butenedioic acid. In case of accidental ingestion, immediate medical attention should be sought. Butenedioic acid is also combustible, and precautions should be taken to avoid exposure to open flames or high temperatures. Proper ventilation is crucial to prevent the accumulation of vapors. It is important to store butenedioic acid in a secure, well-ventilated area, away from incompatible substances. Adhering to proper safety practices is essential when working with butenedioic acid.
| Hazard Symbols | Corrosive (C) |
| Safety Description | – Avoid contact with skin and eyes, – Use in a well-ventilated area, – Wear protective gloves and goggles, – Store in a secure, well-ventilated area |
| Un IDs | UN3265 |
| HS Code | 2917.11.00 |
| Hazard Class | 8 (Corrosive) |
| Packing Group | III |
| Toxicity | May cause irritation to skin, eyes, and respiratory system. Harmful if ingested. |
Acid Synthesis Methods
Various methods enable the synthesis of butenedioic acid. One prevalent approach involves oxidizing maleic anhydride with an oxidizing agent, such as potassium permanganate or hydrogen peroxide, while a catalyst is present. The reaction yields butenedioic acid as the product.
Another method entails hydrolyzing maleic anhydride by reacting it with water, resulting in the formation of butenedioic acid. Depending on the desired conditions and reaction rate, this reaction can occur under acidic or alkaline conditions.
The catalytic oxidation of butane or benzene produces butenedioic acid by oxidizing them with air or oxygen using a catalyst, such as vanadium pentoxide. The resulting reaction mixture undergoes further purification steps to isolate butenedioic acid.
Additionally, microorganisms can ferment specific carbohydrates to synthesize butenedioic acid. This biological method involves the utilization of specific bacteria or fungi that produce butenedioic acid as a metabolic byproduct.
Each of these synthesis methods presents advantages and considerations concerning reaction conditions, scalability, and environmental impact. The choice of method depends on factors such as the desired yield, purity requirements, and overall process feasibility.
Maleic Acid Uses
Butenedioic acid finds various applications due to its versatile properties. Here are some of its uses:
- Polymer production: The production of polymers, such as polyesters and alkyd resins, utilizes butenedioic acid as a precursor, imparting desirable properties like durability and flexibility to these materials.
- Adhesive formulation: Adhesive formulations incorporate butenedioic acid to enhance their bonding capabilities, promoting adhesion between different substrates. This makes it useful in industries such as construction and automotive.
- Food and beverage industry: In the food and beverage industry, butenedioic acid serves as an acidulant and flavor enhancer, adding a sour taste to various products like candies, soft drinks, and fruit juices.
- Textile industry: The textile industry utilizes butenedioic acid in dyeing and finishing processes, where it acts as a dye levelling agent, ensuring uniform color distribution on fabrics.
- Pharmaceutical applications: Butenedioic acid finds application in the pharmaceutical industry for the synthesis of active pharmaceutical ingredients (APIs) and as a pH adjuster in drug formulations.
- Water treatment: Butenedioic acid controls scale and corrosion in water treatment processes, preventing mineral deposits from forming in pipes and equipment.
- Cosmetics and personal care products: Butenedioic acid regulates pH and acts as a chelating agent in cosmetics and personal care products, stabilizing formulations and enhancing their effectiveness.
- Agricultural applications: Butenedioic acid derivatives function as plant growth regulators and herbicides in agriculture, aiding in the control of weed growth and improvement of crop yield.
Butenedioic acid’s diverse range of applications underscores its significance in various industries, contributing to the development of numerous products and processes.
Questions:
Q: How many ionizable H atoms are in each molecule of maleic acid, C4H4O4?
A: There are two ionizable H atoms in each molecule of butenedioic acid.
Q: Does maleic acid have a dipole moment?
A: Yes, butenedioic acid has a dipole moment due to the presence of polar bonds within its structure.
Q: What are the molecular formulas of glyoxyl, maleic acid, and acontic acid?
A: The molecular formulas are as follows: glyoxyl (C2H2O2), butenedioic acid (C4H4O4), acontic acid (C6H6O6).
Q: Is maleic acid or fumaric acid more reactive with bromine?
A: Butenedioic acid is more reactive with bromine compared to fumaric acid.
Q: Would isomerization of maleic acid occur if the reaction were performed in neutral water?
A: No, isomerization of butenedioic acid would not occur in neutral water.
Q: How close were your values of pKa1 and pKa2 for maleic acid?
A: The pKa1 value for butenedioic acid is approximately 1.92, while the pKa2 value is around 6.07.
Q: How to dissolve maleic acid?
A: Butenedioic acid can be dissolved in water by stirring it in at room temperature until it fully dissolves.
Q: When was maleic acid found?
A: Butenedioic acid was discovered in 1834 by the German chemist August Wilhelm von Hofmann.
Q: How does ethanol react with malic acid to form maleic acid?
A: Ethanol reacts with malic acid in the presence of a dehydrating agent, such as sulfuric acid, to form butenedioic acid.
Q: Does maleic acid, when mixed with HCl and heated, form fumaric acid?
A: Yes, butenedioic acid, when mixed with HCl and heated, undergoes an isomerization reaction to form fumaric acid.