Diphenyl ether

Description

Diphenyl ether (diphenyl oxide) is a colorless liquid with a floral odor. It is a white, crystalline solid at temperatures below 80ºF (27ºC). It has low volatility, low solubility in water, and is stable at high temperatures. Avoid contact with oxidizing materials.
Liquid diphenyl oxide is used primarily in industry. It is used in the industrial setting as a heat transfer fluid. It is the major component of Dowtherm A® (an eutectic mixture of phenyl ether and biphenyl) and further as a chemical intermediate in the production of surface-active agents and hightemperature lubricants, and in perfumery due to its geranium-like odour (ACG99b). It is also used as a chemical intermediate in the manufacture of surfactants and fire retardants.
Diphenyl oxide (DPO) is manufactured using the direct phenol method.

Chemical Properties

Diphenyl Ether has not been observed in nature. It is a colorless liquid or a crystalline solid (mp 26.8°C) with an odor reminiscent of geranium leaves. Diphenyl ether is obtained as a by-product in the production of phenol by high-pressure hydrolysis of chlorobenzene. Because of its stability and low price, diphenyl ether is used in large quantities in soap perfumes.

Physical properties

Diphenyl oxide is a practically colorless crystalline solid with a harsh, floral-green, metallic geranium-type odor. clear pale yellowish liquid after melting. It is almost completely insoluble in water, but dissolves in most of the common organic solvents. Its high thermal stability at temperatures as high as 350 to 400°C. together with its noncorrosiveness and general chemical inertness make it eminently suitable as a component of high-boiling heat transfer media.

Occurrence

Reported found in muscat grapes, grilled beef, green tea, potato chips, buckwheat, Bourbon vanilla and lemon balm.

Uses

Diphenyl ether is widely used as a heat transfer agent and a dye carrier. It can be used alone or as a mixture with other materials. Because of its reactivity, It can also be used as a raw material or chemical intermediate to produce commercial products. Diphenyl ether is used in the production of:

1. Diphenyl ether is employed as a processing aid in the production of polyesters. It acts as a chemical intermediate in the production of surface active agents and high temperature lubricants, fire retardants like polybrominated diphenyl ethers (PBDEs) and fragrance for detergents.
2. Heat transfer media – like DOWTHERMTM fluids used for heating industrial processes
3. Alkylated diphenyl oxides – used to make surfactants, greases and lubricants
4. Halogenated diphenyl oxides – used in insecticides, wood preservatives, and flame retardants for appliance casings in consumer electronic products
5. High temperature solvents
6. Coatings
7. Textile dye labeling
8. Plastics – like ethylene-propylene-diene monomer (EPDM) rubber that is used for membrane roofing materials
9. Diphenyl ether plays a vital role in the Ferrario reaction to produce phenoxathiin, which finds application in polyamide and polyimide production. Involving similar reactions, diphenyl ether is a significant side product in the high-pressure hydrolysis of chlorobenzene in the production of phenol.
10. Diphenyl ether is found in alcoholic beverages. Diphenyl ether is present in muscat grapes, green tea, vanilla, lemon balm, buckwheat, potato chips and grilled beef. Diphenyl ether is a flavouring ingredient.

Uses

Phenyl Ether is an Impurity of Propofol (P829750).

Preparation

By heating potassium phenolate with bromobenzene or with chlorobenzene at elevated temperatures.

Definition

ChEBI: Diphenyl ether is an aromatic ether in which the oxygen is attached to two phenyl substituents. It has been found in muscat grapes and vanilla. It has a role as a plant metabolite.

Aroma threshold values

Aroma characteristics at 1.0%: grassy, musty, powdery, dry, terpy, ocimenelike, aromatic and hoplike with green juniper berry nuances.

Taste threshold values

Taste characteristics at 10 ppm: dry chemical, floral rosey with carrot, tropical and hoplike terpy notes and a green vegetative and woody nuance.

Synthesis Reference(s)

Synthetic Communications, 13, p. 335, 1983 DOI: 10.1080/00397918308066985
Synthesis, p. 204, 1991 DOI: 10.1055/s-1991-26419

General Description

Colorless liquid with a mild pleasant odor. May float or sink in water. Freezing point is 81°F.

General Description

Diphenyl ether occurs, e.g., in lemon balm oil. The compound forms colorless crystals that possess a geranium-like aroma. Diphenyl ether is formed as a byproduct in the high-pressure hydrolysis of chlorobenzene. Because of its high thermal stability, a eutectic mixture of diphenyl ether and biphenyl is employed as a heat transfer medium. Diphenyl ether is the starting material for organic intermediates and is used as a fragrance component. The compound is also employed as a processing aid in the production of polyesters; several polybromine derivatives of diphenyl ether are used as fire retardants.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Diphenyl oxide can react with oxidizing materials. . A vigorous reaction occurred between the ether and chlorosulfuric acid.

Health Hazard

Inhalation may cause nausea because of disagreeable odor. Contact of liquid with eyes causes mild irritation. Prolonged exposure of skin to liquid causes reddening and irritation. Ingestion produces nausea.

Fire Hazard

Diphenyl oxide is combustible.

Flammability and Explosibility

Non flammable

Safety Profile

Moderately toxic by ingestion. Prolonged exposure damages liver, spleen, kidneys, and thyroid, and upsets gastrointestinal tract. A skin and eye irritant. Combustible when exposed to heat or flame; can react with oxidizing materials. For explosion hazard, see ETHERS. To fight fire, use water, foam, CO2, dry chemical. When heated to decomposition it emits acrid smoke and irritating fumes

Potential Exposure

Strong oxidizers may cause fire andexplosions. Attacks some plastics, rubber, and coatings.

First aid

Wear protective gloves andclothing to prevent any reasonable probability of skin contact. Safety equipment suppliers/manufacturers can providerecommendations on the most protective glove/clothingmaterial for your operation. All protective clothing (suits,gloves, footwear, headgear) should be clean, available eachday, and put on before work. Contact lenses should not beworn when working with this chemical. Wear splash-proofgoggles and face shield if working with the liquid or dustproof chemical goggles and face shield if working with thecrystalline material, unless full face-piece respiratory protection is worn. Employees should wash immediately withsoap when skin is wet or contaminated. Provide emergencyshowers and eyewash.Respirator Selection: 2

Carcinogenicity

Phenyl ether was not mutagenic in the Ames Salmonella assay with or without metabolic activation.

storage

Color Code—Green: General storage may be used.Prior to working with diphenyl oxide you should be trainedon its proper handling and storage. Before entering confinedspace where this chemical may be present, check to makesure that an explosive concentration does not exist. Store intightly closed containers in a cool, well-ventilated areaaway from oxidizers. Store in tightly closed containers in acool, well-ventilated area away from heat. Sources of ignition, such as smoking and open flames, are prohibitedwhere this chemical is used, handled, or stored in a mannerthat could create a potential fire or explosion hazard. Metalcontainers involving the transfer of 5 gallons or more ofthis chemical should be grounded and bonded. Drums mustbe equipped with self-closing valves, pressure vacuumbungs, and flame arresters. Use only nonsparking tools andequipment, especially when opening and closing containersof this chemical.

Shipping

The name of this material is not in the DOT listof materials for label and packaging standards. However,based on regulations, it may be classified as anEnvironmentally hazardous substances, solid, n.o.s. Thischemical requires a shipping label of “CLASS 9.” It falls inHazard Class 9 and Packing Group III.[20,

Purification Methods

Crystallise the ether from 90% EtOH. Melt it, wash it with 3M NaOH and water, dry it with CaCl2 and fractionally distil it under reduced pressure. Fractionally recrystallise it from its melt and store over P2O5. [Beilstein 6 IV 562.]

Toxics Screening Level

The initial threshold screening level (ITSL) for diphenyloxide (also known as phenyl ether) is 70 μg/m3 based on an eight hour averaging time.