Benzoyl chloride

Physical and Chemical Properties

The pure product of benzoyl chloride is a colorless and transparent flammable liquid, which is smoking exposed to air in the air. In Industry, it is slightly pale yellow, with a strong pungent odor. Its steam has a strong stimulating effect on eye mucous membranes, skin, and respiratory tract, by stimulating the mucous membranes and eyes tear. Its melting point is-1.0 ℃, boiling point is 197.2 ℃, relative density is 1.212 (20 ℃), flash point is 72 ℃, and refractive index (n20) is 1.554. It is soluble in ether, chloroform, benzene, and carbon disulfide. It can gradually be decomposed in water or ethanol, ammonia, which generates benzoic acid, benzamide, ethyl benzoate, and hydrogen chloride. In the laboratory, it can be obtained by distillation of benzoic acid and phosphorus pentachloride under anhydrous conditions. The industrial production process can be obtained by the use of thionyl chloride benzaldehyde. Benzoyl chloride is an important intermediate for preparing dyes, perfumes, organic peroxides, resins, and drugs. It is also used in photography and artificial tannin production, which was formerly used as an irritant gas in chemical warfare.

Application

Benzoyl chloride could used as a raw material in organic synthesis, dye, and pharmaceuticals. It can also used as a manufacturing initiator for benzoyl peroxide, t-butyl peroxybenzoate, pesticides, and herbicides. In pesticides, it is a new insecticide that is inducible isoxazole parathion (Isoxathion, Karphos) intermediate. Benzoyl chloride is an important benzoyl and benzyl reagent. Most benzoyl chloride is used in the production of benzoyl peroxide, and secondly for the production of benzophenone, benzyl benzoate, and benzyl cellulose. Benzoyl peroxide catalyzes polymerization initiator for the monomer plastic, polyester, epoxy, acrylic resin production, self-curing agent, which is a glass fiber material, fluorine rubber, silicone crosslinking agents, oil refined, bleached flour, and fiber decolorizing.

Description

Benzoyl chloride is a colorless to slightbrown liquid with a strong, penetrating odor. Molecularweight = 140.57;Boiling point = 197.2℃ at 760 mmHg;Freezing/Melting point= 2 1℃; Flash point = 72℃;Vapor pressure =0.38 mmHg at 20℃; Autoignitiontemperature=197℃. Explosive limits in air:Lower=2.5%; Upper=27%.Hazard Identification(based on NFPA-704 M Rating System): Health 3,Flammability 2, Reactivity 2 (water reactive).Decomposes in water.

Chemical Properties

Benzoyl chloride is a colorless to slight brown liquid with a strong, penetrating odor; vapor causes tears. Soluble in ether and carbon disulfide; decomposes in water. Combustible. It is a liquid acyl chloride used as a benzoylating agent.

Uses

Benzoyl chloride is widely utilized for the synthesis of peroxides. It is employed in the production of dyes and perfumes. It also serves in the manufacturing of pharmaceuticals and resins.

Uses

For acylation, i.e., introduction of the benzoyl group into alcohols, phenols, and amines (Schotten-Baumann reaction); in the manufacture of benzoyl peroxide and of dye intermediates. In organic analysis for making benzoyl derivatives for identification purposes.

Definition

ChEBI: Benzoyl chloride is an acyl chloride consisting of benzene in which a hydrogen is replaced by an acyl chloride group. It is an important chemical intermediate for the manufacture of other chemicals, dyes, perfumes, herbicides and pharmaceuticals. It has a role as a carcinogenic agent. It is an acyl chloride and a member of benzenes. It is functionally related to a benzoic acid.?

Production Methods

Benzoyl chloride can be prepared from benzoic acid by reaction with PCl5 or SOCl2, from benzaldehyde by treatment with POCl3 or SO2 Cl2, from benzotrichloride by partial hydrolysis in the presence of H2SO4 or FeCl3, from benzal chloride by treatment with oxygen in a radical source, and from several other miscellaneous reactions. Benzoyl chloride can be reduced to benzaldehyde, oxidized to benzoyl peroxide, chlorinated to chlorobenzoyl chloride and sulfonated to m-sulfobenzoic acid. It will undergo various reactions with organic reagents. For example, it will add across an unsaturated (alkene or alkyne) bond in the presence of a catalyst to give the phenylchloroketone:

Synthesis Reference(s)

Journal of the American Chemical Society, 73, p. 702, 1951 DOI: 10.1021/ja01146a061
Synthesis, p. 306, 1983 DOI: 10.1055/s-1983-30314

General Description

Benzoyl chloride appears as a colorless fuming liquid with a pungent odor. Flash point 162 °F. Lachrymator, irritating to skin and eyes. Corrosive to metals and tissue. Density 10.2 lb / gal. Used in medicine and in the manufacture of other chemicals.

Reactivity Profile

Benzoyl chloride reacts violently with protic solvents such as alcohols, with amines and amides (for example dimethylformamide [Bretherick 1979 p. 6] ) and with inorganic bases. Causes the violent decomposition of dimethyl sulfoxide [Chem. Eng. News 35(9): 87 1957]. May react vigorously or explosively if mixed with diisopropyl ether or other ethers in the presence of trace amounts of metal salts [J. Haz. Mat., 1981, 4, 291]. Friedel-Crafts acylation of naphthalene using Benzoyl chloride, catalyzed by AlCl3, must be conducted above the melting point of the mixture, or the reaction may be violent [Clar, E. et al., Tetrahedron, 1974, 30, 3296].

Hazard

Highly toxic. Strong irritant to skin, eyes, and mucous membranes, and via ingestion, inhala- tion. Upper respiratory tract irritant. Probable car- cinogen.

Health Hazard

INHALATION: may irritate eyes, nose and throat. INGESTION: causes acute discomfort. SKIN: causes irritation and burning.

Chemical Reactivity

Reactivity with Water Slow reaction with water to produce hydrochloric acid fumes. The reaction is more rapid with steam; Reactivity with Common Materials: Slow corrosion of metals but no immediate danger; Stability During Transport: Not pertinent; Neutralizing Agents for Acids and Caustics: Soda ash and water, lime; Polymerization: Does not occur; Inhibitor of Polymerization: Not pertinent.

Mechanism of action

Indicative of its high reactivity (relative to alkyl chlorides), benzyl chloride reacts with water in a hydrolysis reaction to form benzyl alcohol and hydrochloric acid. In contact with mucous membranes, hydrolysis produces hydrochloric acid. Thus, benzyl chloride is a lachrymator and has been used in chemical warfare. Theoretically, for every mole of benzyl chloride reacted, one mole of hydrochloric acid is released[1].

Toxicology

Benzoyl chloride is of low acute oral toxicity in rats (LD₅₀ 2529 mg/kg). It is more toxic by inhalation (LC₅₀ 230 ppm, 4 h in male rats and 314 ppm, 4 h in female rats). The compound is irritating to skin, mucous membranes, eyes, and the respiratory tract.
When benzoyl chloride or solutions of benzoyl chloride in benzene were applied to the skin of mice for up to 10 months irritation and keratinization resulted, and to some extent, ulceration and necrosis of the skin occurred. A few tumors (skin, lung) were observed in those mice. There is no clear evidence that benzoyl chloride is mutagenic.
For humans, benzoyl chloride is classified as a lachrymator. It is irritating to the skin, eyes, and mucous membranes. The available data are inadequate to evaluate the carcinogenic potential of benzoyl chloride to humans.

Potential Exposure

Benzoyl chloride is used as a chemical intermediate; in organic synthesis; to produce other chemicals, dyes, perfumes, herbicides, and medicines.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medicalattention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. If victim is conscious, administer water ormilk. Do not induce vomiting. Medical observation isrecommended for 24
48 h after breathing overexposure, aspulmonary edema may be delayed. As first aid for pulmonaryedema, a doctor or authorized paramedic may consideradministering a corticosteroid spray.

storage

(1) Color Code—Red Stripe: FlammabilityHazard: Do not store in the same area as other flammablematerials. Color Code—White: (2) Corrosive or ContactHazard; Store separately in a corrosion-resistant location.Store in a cool, dry, well-ventilated area preferably in adetached warehouse. Keep away from sources of ignition.Avoid physical damage to the container.

Shipping

UN 1736 Benzoylchloride, Hazard class: 8; Labels: 8—Corrosive material.

Purification Methods

A solution of benzoyl chloride (300mL) in *C6H6 (200mL) is washed with two 100mL portions of cold 5% NaHCO3 solution, separated, dried with CaCl2 and distilled [Oakwood & Weisgerber Org Synth III 113 1955]. Repeated fractional distillation at 4mm Hg through a glass helices-packed column (avoiding porous porcelain or silicon-carbide boiling chips, and hydrocarbon or silicon greases on the ground joints) gave benzoyl chloride that did not darken on addition of AlCl3. Further purification is achieved by adding 3 mole% each of AlCl3 and toluene, standing overnight, and distilling off the benzoyl chloride at 1-2mm [Brown & Jenzen J Am Chem Soc 80 2291 1958]. Refluxing for 2hours with an equal weight of thionyl chloride before distillation has also been used. [Beilstein 9 IV 721.] Strong IRRITANT. Use in a fume cupboard.

Incompatibilities

May form explosive mixture with air. Contact with heat, hot surfaces, and flames causes decomposition, forming phosgene and hydrogen chloride. Water contact may be violent; forms hydrochloric acid. Reactions with amines, alcohols, alkali metals, dimethyl sulfoxide, strong oxidizers, and metal salts may be violent, causing fire and explosions. Attacks metals in the presence of moisture, forming explosive hydrogen gas. Attacks some plastics, rubber or coatings.

Waste Disposal

Pour into sodium bicarbonate solution and flush to sewer.

References

[1] Tsonis C, et al. 26 - Polybenzyls. 1989; 5: 455-464.