Does MTBE dissolve in water?
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I would like to ask whether methyl tert-butyl ether is soluble in water? If possible, are there any data to support this? And will it have an impact on quality?
Reply 1# wc1527 MTBE is a colorless, low-viscosity liquid. Melting point: -109°C, boiling point: 55.3°C, freezing point: -108.6°C, relative density: 0.7407 (20/4°C), refractive index: 1.3694. Flash point (closed cup) –28°C, ignition point 460°C, explosion limit (in air) 1.65%-8.4% (by volume), vapor pressure (25°C) 32.664 kPa, critical pressure 3.43 MPa, critical temperature 223.95°C, viscosity (20°C) 0.36 mPa·s. It is miscible with gasoline and many organic solvents, slightly soluble in water, and can form azeotropic mixtures with certain polar solvents such as water, methanol, and ethanol. It has a scent similar to terpenes.
MTBE is soluble in water, but I’m not sure where to find the relevant data; I also hope to see experts provide an answer.
Physical properties Density (kg/m3, 20°C): 740.6 Critical temperature (°C): 223.9 Specific heat capacity (°C): 2.135 Vaporization heat (J/(g·K)): 30.10 Heat of combustion (MJ/kg): 38.21 Red vapor pressure (bar): 0.55 Critical pressure (KPC): 223.9 Refractive index (20 °C): 1.3689 Ignition point (°C): 480 Explosive limit in air (%V): Upper limit 1.65； Lower limit: 8.4 Research octane number: 117 Motor octane number: 101 Solubility of water in MTBE (20°C, g/100g): 1.5 Solubility of MTBE in water (20°C, g/100g): 4.3
Baidu Information: MTBE Directory – Introduction, Components, Toxicity of MTBE, Synthesis of MTBE, Physical Properties. Structure diagram of MTBE: Methyl tert-butyl ether, abbreviated as MTBE, has a melting point of -109°C and a boiling point of 55.2°C. It is a colorless, transparent liquid with a high octane rating; it possesses an ether-like odor. It is an ideal component for producing lead-free, high-octane oxygenated gasoline, and is widely used around the world as a gasoline additive. It not only effectively increases the octane rating of gasoline, but also improves vehicle performance, reduces the CO content in exhaust gases, and lowers the production costs of gasoline. Furthermore, MTBE is also an important chemical raw material; for example, high-purity isobutylene can be produced through cracking. MTBE is an organic ether with an oxygen content of 18.2%. Its vapor is heavier than air and can spread along the ground; it can burn when in contact with strong oxidizers. The purity of MTBE is approximately 97% to 99.5%. Its molecular formula is CH3OC(CH3)3, with a relative molecular weight of 88.15. The CAS number is 1634-04-4. Methyl tert-butyl ether is an additive for gasoline with a high octane rating (115 on the research octane scale). It contains much less oxygen than methanol, which helps in warming up the engine and saving fuel. Its low evaporation heat capacity is advantageous for cold starts, and it is commonly used in the formulation of lead-free and low-lead gasoline. It can also be re-fragmented into isobutylene, which serves as a raw material for rubber and other chemical products. The highest-quality methyl tert-butyl ether can be used in pharmaceuticals and serves as a pharmaceutical intermediate. Commonly known as “pharmaceutical-grade MTBE”; Baidu Baike provides an explanation for “pharmaceutical-grade methyl tert-butyl ether”. High purity is required, along with stable batch quality and a small range of fluctuations. Edit this section’s components. MTBE is a component of high-octane gasoline; its base octane number is RON: 118, MON: 100. It is an excellent additive for increasing the octane rating of gasoline as well as an anti-knock agent. MTBE and gasoline are mutually soluble in any proportion without layering; when blended with gasoline components, it exhibits a good blending effect, resulting in a blending octane number that is higher than its pure octane number. MTBE has a relatively high oxygen content, which can significantly improve automobile exhaust emissions. However, if the proportion of MTBE added is not controlled, causing the theoretical stoichiometric air-fuel ratio to exceed the range within which the electronic control unit of the engine with closed-loop control can make adjustments, the excess oxygen will interfere with the closed-loop control and reduce the conversion efficiency of the three-way catalytic converter. Research has also shown that MTBE contaminates groundwater sources; as a result, states such as California in the United States are preparing to ban MTBE. Research by a research institution in Japan also shows that when the MTBE content in gasoline exceeds 7%, nitrogen oxides emitted by vehicles increase. Therefore, in premium lead-free gasoline in Japan, the amount of MTBE added does not exceed 7%. Edit this paragraph: Toxicity of MTBE MTBE has certain toxicity. Research on its toxicity began in the late 1980s. Studies have found that it mixes easily with water and can penetrate the soil, damaging groundwater quality, leading to it being considered a potential pollutant. MTBE is primarily absorbed through the respiratory tract, but it can also be absorbed through the skin and digestive tract; in animals, exposure to high concentrations of MTBE can cause cancer. In mice, the **concentration is 1.0 mmol/L, and the lethal concentration is 1.6 mmol/L. The effects on the human body are mainly manifested as irritative reactions in the upper respiratory tract and eye mucosa, while long-term exposure can cause dry skin. The U.S. EPA recommends a quality concentration of MTBE in drinking water of 5.2–10.3 micrograms/L. Editing this section: Synthesis of MTBE MTBE is generally synthesized using methanol and isobutylene as raw materials, with the aid of acidic catalysts; among these, resin catalysts are the most commonly used in industry. Different synthetic routes have been developed due to the various sources of isobutylene. Sources of isobutylene:
– C4 fractions produced as a by-product of ethylene production via cracking
– C4 fractions generated as a by-product of catalytic cracking units in refineries
– Obtained by isomerization and dehydrogenation of n-butane
Catalysts for synthesizing MTBE:
– Hydrofluoric acid
– Sulfuric acid
– Styrene-based cation exchange resins
– Solid acids
– Molecular sieves
Reaction equation:
The reaction to form MTBE is a selective addition reaction; the tertiary carbon atom in the alkene forms a carbocation in the presence of an acidic catalyst, which then combines with an alcohol to form an ether. Its reaction is a reversible exothermic reaction. Edit this section: Physical properties Density (kg/m3, 20°C): 740.6 Critical temperature (°C): 223.9 Specific heat capacity (°C): 2.135 Heat of vaporization (J/(g·K)): 30.10 Heat of combustion (MJ/kg): 38.21 Red vapor pressure (bar): 0.55 Critical pressure (KPC): 223.9 Refractive index (20 °C): 1.3689 Ignition point (°C): 480 Explosive limit in air (%V): Upper limit 1.65 ； Lower limit: 8.4 Research octane number: 117 Motor octane number: 101 Solubility of water in MTBE (20°C, g/100g): 1.5 Solubility of MTBE in water (20°C, g/100g): 4.3 Applications Methyl tert-butyl ether is currently used as a substitute for tetraethyl lead. It is produced by using isobutylene and methanol from cracked C4 as raw materials, under the catalysis of macroporous sulfonic acid cation exchange resin, and then refined. Product properties: This product has a camphor-like odor, is colorless and transparent. At room temperature, it is fully miscible with alcohols, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated solvents, etc. Like other methyl tert-alkyl ethers, this product also possesses another very important property, namely a strong resistance to auto-oxidation, making it less likely to form peroxides. It is mainly used by refineries as a blending agent for high-octane gasoline, and can also serve as a solvent for paraffins, oils, fragrances, alkaloids, resins, and rubber, as well as a reagent in organic synthesis reactions. It is flammable and volatile, and poses a risk of explosion in the presence of ignition sources or heat. In the 1970s, MTBE began to attract attention as a gasoline blending component to improve gasoline octane rating. MTBE can increase the octane rating of gasoline, and it has stable chemical properties. Gasoline with added MTBE can also improve a vehicle’s driving performance and reduce the level of carbon monoxide in exhaust gases. It also has a high combustion efficiency, which helps to suppress the formation of ozone. It can replace tetraethyl lead as an anti-knock agent to produce lead-free gasoline. Currently, about 95% of MTBE is used as an octane booster and an oxygenate in gasoline. MTBE is also an important raw material for producing polymeric isobutylene. It is also used in the production of methacraldehyde and methacrylic acid. In 1973, Italy developed the world’s first set of MTBE industrial plants. The Air Clean Act Amendment (CAA-1990) enacted in the United States in 1990 required new formulations of gasoline to contain oxygenates such as MTBE in order to reduce vehicle pollution. China began researching MTBE technology in the late 1970s and early 1980s. In 1983, the rubber factory of Qilu Petrochemical Company built China’s first industrial MTBE testing facility, and in 1986, Jihua Company constructed China’s first MTBE production plant with a capacity of 10,000 tons per year. In 1999, China launched the \"National Air Purification Project – Clean Vehicles Initiative\", beginning to encourage the use of gasoline containing MTBE. As an octane booster for gasoline, MTBE not only increases the oxygen content in gasoline but also promotes cleaner combustion, thereby reducing harmful emissions from vehicles. MTBE is highly soluble in water. Primarily due to leaks from underground and above-ground gasoline tanks, the United States has increasingly detected MTBE in underground drinking water sources. MTBE can cause unpleasant odors in water quality even at very low concentrations. The U.S. Environmental Protection Agency has listed MTBE as a possible human carcinogen. MTBE is added to gasoline in the United States not only to meet the requirement of 2% oxygen content in gasoline, but also because MTBE has the advantage of a road octane rating of 110 and an RVP (Reid Vapor Pressure) of only 8 (pounds per square inch). Adding MTBE meets the requirement of 2% oxygen content in gasoline, increasing its volume by 11%. The United States originally set 3.65% of the total gasoline volume to be MTBE, and about 87% of gasoline in the new formulations uses MTBE as an oxygenate. Due to the pollution of water quality caused by MTBE, California in the United States banned its use starting in 2004, while states such as Arizona, Connecticut, and New York also banned MTBE starting in 2005. Other states have also reduced the amount of MTBE added and joined the ranks of those that have banned it. Australia also banned MTBE in 2004. Since 2006, the pace of banning MTBE in gasoline in the United States has accelerated further. Since May 2006, 25 states in the United States have banned MTBE. The demand for MTBE in the United States is expected to decline from 12.9 million tons per year in 2001 to 3.44 million tons per year by 2010. Global MTBE demand reached a peak of 22.58 million tons per year in 2001, and it is predicted that demand will further decline in the future.
– C4 fractions produced as a by-product of ethylene production via cracking
– C4 fractions generated as a by-product of catalytic cracking units in refineries
– Obtained by isomerization and dehydrogenation of n-butane
Catalysts for synthesizing MTBE:
– Hydrofluoric acid
– Sulfuric acid
– Styrene-based cation exchange resins
– Solid acids
– Molecular sieves
Reaction equation:
The reaction to form MTBE is a selective addition reaction; the tertiary carbon atom in the alkene forms a carbocation in the presence of an acidic catalyst, which then combines with an alcohol to form an ether. Its reaction is a reversible exothermic reaction. Edit this section: Physical properties Density (kg/m3, 20°C): 740.6 Critical temperature (°C): 223.9 Specific heat capacity (°C): 2.135 Heat of vaporization (J/(g·K)): 30.10 Heat of combustion (MJ/kg): 38.21 Red vapor pressure (bar): 0.55 Critical pressure (KPC): 223.9 Refractive index (20 °C): 1.3689 Ignition point (°C): 480 Explosive limit in air (%V): Upper limit 1.65 ； Lower limit: 8.4 Research octane number: 117 Motor octane number: 101 Solubility of water in MTBE (20°C, g/100g): 1.5 Solubility of MTBE in water (20°C, g/100g): 4.3 Applications Methyl tert-butyl ether is currently used as a substitute for tetraethyl lead. It is produced by using isobutylene and methanol from cracked C4 as raw materials, under the catalysis of macroporous sulfonic acid cation exchange resin, and then refined. Product properties: This product has a camphor-like odor, is colorless and transparent. At room temperature, it is fully miscible with alcohols, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated solvents, etc. Like other methyl tert-alkyl ethers, this product also possesses another very important property, namely a strong resistance to auto-oxidation, making it less likely to form peroxides. It is mainly used by refineries as a blending agent for high-octane gasoline, and can also serve as a solvent for paraffins, oils, fragrances, alkaloids, resins, and rubber, as well as a reagent in organic synthesis reactions. It is flammable and volatile, and poses a risk of explosion in the presence of ignition sources or heat. In the 1970s, MTBE began to attract attention as a gasoline blending component to improve gasoline octane rating. MTBE can increase the octane rating of gasoline, and it has stable chemical properties. Gasoline with added MTBE can also improve a vehicle’s driving performance and reduce the level of carbon monoxide in exhaust gases. It also has a high combustion efficiency, which helps to suppress the formation of ozone. It can replace tetraethyl lead as an anti-knock agent to produce lead-free gasoline. Currently, about 95% of MTBE is used as an octane booster and an oxygenate in gasoline. MTBE is also an important raw material for producing polymeric isobutylene. It is also used in the production of methacraldehyde and methacrylic acid. In 1973, Italy developed the world’s first set of MTBE industrial plants. The Air Clean Act Amendment (CAA-1990) enacted in the United States in 1990 required new formulations of gasoline to contain oxygenates such as MTBE in order to reduce vehicle pollution. China began researching MTBE technology in the late 1970s and early 1980s. In 1983, the rubber factory of Qilu Petrochemical Company built China’s first industrial MTBE testing facility, and in 1986, Jihua Company constructed China’s first MTBE production plant with a capacity of 10,000 tons per year. In 1999, China launched the \"National Air Purification Project – Clean Vehicles Initiative\", beginning to encourage the use of gasoline containing MTBE. As an octane booster for gasoline, MTBE not only increases the oxygen content in gasoline but also promotes cleaner combustion, thereby reducing harmful emissions from vehicles. MTBE is highly soluble in water. Primarily due to leaks from underground and above-ground gasoline tanks, the United States has increasingly detected MTBE in underground drinking water sources. MTBE can cause unpleasant odors in water quality even at very low concentrations. The U.S. Environmental Protection Agency has listed MTBE as a possible human carcinogen. MTBE is added to gasoline in the United States not only to meet the requirement of 2% oxygen content in gasoline, but also because MTBE has the advantage of a road octane rating of 110 and an RVP (Reid Vapor Pressure) of only 8 (pounds per square inch). Adding MTBE meets the requirement of 2% oxygen content in gasoline, increasing its volume by 11%. The United States originally set 3.65% of the total gasoline volume to be MTBE, and about 87% of gasoline in the new formulations uses MTBE as an oxygenate. Due to the pollution of water quality caused by MTBE, California in the United States banned its use starting in 2004, while states such as Arizona, Connecticut, and New York also banned MTBE starting in 2005. Other states have also reduced the amount of MTBE added and joined the ranks of those that have banned it. Australia also banned MTBE in 2004. Since 2006, the pace of banning MTBE in gasoline in the United States has accelerated further. Since May 2006, 25 states in the United States have banned MTBE. The demand for MTBE in the United States is expected to decline from 12.9 million tons per year in 2001 to 3.44 million tons per year by 2010. Global MTBE demand reached a peak of 22.58 million tons per year in 2001, and it is predicted that demand will further decline in the future.
It is soluble in water. Let me tell you a case I experienced. There is an MTBE tank in the 97# gasoline storage area; water was injected into it when there was residual MTBE at the bottom of the tank (that is, the tank had not been thoroughly cleaned), in order to treat the pipelines. Later, the remaining water was poured into the sewer system and flowed to the wastewater treatment plant. As a result, the activated sludge in the wastewater treatment plant was killed. The reason is that MTBE dissolves in water. Without dissolved MTBE, it becomes miscible with the oils in the wastewater. Be careful with water that has dissolved MTBE – it is difficult to handle, and it’s not the same as dealing with wastewater.
Reply to 6# guyusdog: Thank you for the expert’s answer; I’ve learned something from it, thanks!