Thionyl chloride is a chemical compound used in various industrial applications. It reacts with alcohols and carboxylic acids, producing corresponding chlorides and sulfuryl chloride, respectively.
| IUPAC name | Thionyl chloride |
| Molecular formula | SOCl₂ |
| CAS number | 7719-09-7 |
| Synonyms | Sulfurous dichloride, Sulfur oxychloride, Thionyl dichloride |
| InChI | InChI=1S/Cl2OS/c1-4(2)3 |
Thionyl Chloride Properties
Thionyl Chloride Formula
The formula of thionyl dichloride is SOCl₂, representing one sulfur atom bonded to two chlorine atoms. It is a widely used chemical compound in various industries.
Thionyl Chloride Molar Mass
Thionyl dichloride has a molar mass of approximately 118.97 grams per mole. The molar mass is determined by summing the atomic masses of its constituent elements.
Thionyl Chloride Boiling Point
Thionyl dichloride has a boiling point of around 79.6 degrees Celsius. This is the temperature at which the liquid form of thionyl dichloride changes into a gaseous state.
Thionyl Chloride Melting Point
The melting point of thionyl dichloride is approximately -104.5 degrees Celsius. This is the temperature at which the solid form of thionyl dichloride transitions into a liquid state.
Thionyl Chloride Density g/mL
Thionyl dichloride has a density of about 1.64 grams per milliliter. Density is the measure of mass per unit volume and is an important characteristic of a substance.
Thionyl Chloride Molecular Weight
The molecular weight of thionyl dichloride is roughly 118.97 grams per mole. It is calculated by adding the atomic weights of sulfur, chlorine, and oxygen.
Thionyl Chloride Structure
The structure of thionyl dichloride consists of one sulfur atom bonded to two chlorine atoms. The sulfur and chlorine atoms are arranged linearly, forming a molecule with a bent shape.
Thionyl Chloride Solubility
Thionyl dichloride is sparingly soluble in water but dissolves readily in organic solvents such as benzene, toluene, and carbon tetrachloride. Its solubility is an important factor in its applications.
| Appearance | Colorless to pale yellow liquid |
| Specific Gravity | 1.638 g/mL |
| Color | Colorless |
| Odor | Pungent, suffocating |
| Molar Mass | 118.97 g/mol |
| Density | 1.638 g/mL |
| Melting Point | -104.5 °C |
| Boiling Point | 79.6 °C |
| Flash Point | Not applicable |
| Water Solubility | Reacts violently |
| Solubility | Soluble in organic solvents such as benzene, toluene, and carbon tetrachloride |
| Vapour Pressure | 4.33 kPa at 20 °C |
| Vapour Density | 3.9 (air = 1) |
| pKa | -6.3 |
| pH | Not applicable |
Thionyl Chloride Safety and Hazards
Thionyl dichloride poses several safety hazards and must be handled with care. It is highly corrosive and can cause severe burns upon contact with skin, eyes, or mucous membranes. Inhalation of its vapors can lead to respiratory irritation and damage. The compound reacts violently with water, releasing toxic gases, such as hydrogen chloride. Therefore, it should be stored and handled away from moisture sources. Thionyl dichloride also reacts vigorously with alcohols and water-containing compounds, which can result in fire or explosion hazards. Adequate ventilation, personal protective equipment, and proper storage practices are essential to ensure safe handling of thionyl dichloride.
| Hazard Symbols | Corrosive (C), Toxic (T), Dangerous for the Environment (N) |
| Safety Description | – Keep away from moisture sources and incompatible substances.<br>- Use in a well-ventilated area and wear appropriate personal protective equipment.<br>- Handle with care to avoid contact with skin, eyes, and mucous membranes.<br>- Store in a tightly closed container in a cool, dry place. |
| UN IDs | UN 1836 (Thionyl dichloride) |
| HS Code | 2812.10.00 |
| Hazard Class | 8 (Corrosive substances) |
| Packing Group | II (Moderately hazardous) |
| Toxicity | Highly toxic by inhalation, ingestion, and skin absorption.<br>- Can cause severe burns and respiratory irritation.<br>- May have long-term harmful effects on aquatic organisms. |
Thionyl Chloride Synthesis Methods
Different methods allow for the synthesis of thionyl dichloride.
One common approach involves the reaction between sulfur trioxide (SO₃) and sulfur dichloride (SCl₂) in the presence of a catalyst like activated carbon or aluminum chloride. The reaction proceeds at elevated temperatures, typically around 300-400°C, and produces thionyl dichloride as a result.
Another method involves the direct reaction of sulfur dioxide (SO₂) with phosphorus pentachloride (PCl₅) or phosphorus oxychloride (POCl₃). This reaction takes place under reflux conditions, with the gradual addition of the reagents, and yields thionyl dichloride.
The reaction of sulfur with phosphorus trichloride (PCl₃) yields thionyl dichloride. This process involves heating the reactants and allowing the formation of thionyl dichloride.
Another method involves the reaction between phosphorus pentasulfide (P₂S₅) and phosphorus pentachloride (PCl₅) in the presence of a Lewis acid catalyst such as aluminum chloride. The reaction occurs at elevated temperatures and results in the formation of thionyl dichloride.
It is important to note that these synthesis methods require proper handling and safety precautions due to the hazardous nature of the reactants involved. The safe and effective synthesis of thionyl dichloride requires the expertise of experienced chemists and the use of proper laboratory equipment.
Thionyl Chloride Uses
Thionyl dichloride finds numerous applications across various industries due to its versatile chemical properties. Here are some common uses of thionyl dichloride:
- Conversion of Carboxylic Acids: Thionyl dichloride converts carboxylic acids into acyl chlorides, utilizing the Vilsmeier-Haack reaction extensively in organic synthesis.
- Alcohol Chlorination: Thionyl dichloride reacts with alcohols, forming alkyl chlorides and finding application in the production of chlorinated compounds for pharmaceuticals and agrochemicals, known as the Darzens reaction.
- Dehydration Agent: Thionyl dichloride acts as a dehydrating agent, facilitating the removal of water from various compounds. It finds common usage in synthesizing dyes, perfumes, and pharmaceutical intermediates.
- Lithium-Ion Battery Manufacturing: Manufacturers employ thionyl dichloride in producing lithium-thionyl dichloride batteries, which exhibit high energy density and long shelf life. These batteries have applications in medical devices, military equipment, and remote sensors.
- Polymerization Reactions: Thionyl dichloride participates in polymerization reactions, contributing to the synthesis of diverse polymers, including polycarbonates and polyanhydrides.
- Phosphorus Compounds: Thionyl dichloride reacts with phosphorus compounds, such as phosphorus trichloride, producing phosphoryl chlorides. Chemists utilize these intermediates to synthesize organophosphorus compounds and flame retardants.
- Chemical Reagent: Thionyl dichloride serves as a versatile reagent in numerous chemical transformations, including esterification, halogenation, and nucleophilic substitution reactions.
Questions:
Q: What can thionyl chloride be flushed with?
A: Thionyl dichloride can be flushed with a large excess of a compatible alcohol or base, such as methanol or sodium bicarbonate solution.
Q: What is the product of valeric acid with thionyl chloride?
A: The reaction of valeric acid with thionyl dichloride produces valeryl chloride, along with sulfur dioxide gas.
Q: Can you add thionyl chloride with a carboxylic acid?
A: Yes, thionyl dichloride can be added to a carboxylic acid to convert it into an acyl chloride through the Vilsmeier-Haack reaction.
Q: Which of the following is the correct Lewis formula for thionyl chloride (SOCl2)?
A: The correct Lewis formula for thionyl dichloride (SOCl2) is represented as S=O | Cl – Cl.
Q: What drives the thionyl chloride reaction?
A: The thionyl dichloride reaction is driven by the high reactivity of thionyl chloride, which acts as an electrophile in various chemical transformations.
Q: How to quench thionyl chloride?
A: Thionyl dichloride can be quenched by adding a suitable quenching agent such as a primary or secondary alcohol, or by carefully hydrolyzing it with water.
Q: What would you get if you mix amines with thionyl chloride?
A: Mixing amines with thionyl dichloride results in the formation of corresponding amine hydrochloride salts.
Q: What is thionyl chloride?
A: Thionyl dichloride is a chemical compound with the formula SOCl2, commonly used as a reagent in organic synthesis and as a dehydrating agent.
Q: What will excess thionyl chloride do?
A: Excess thionyl dichloride can lead to vigorous reactions, potentially resulting in the production of toxic gases or explosion hazards, and should be handled with caution.
Q: How to neutralize thionyl chloride?
A: Thionyl dichloride can be neutralized by carefully adding it to a large excess of a suitable base, such as sodium bicarbonate or sodium hydroxide, while ensuring appropriate safety measures.