What Are Different Uses of Organic Solvents?

Organic solvents are a large class of organic compounds that are widely used in daily life and production. They have a small molecular weight and are found in coatings, adhesives, lacquers and cleaners. Organic solvents such as styrene, perchloroethylene, trichloroethylene, ethylene glycol ether, and triethanolamine are often used.

It exists in paint,

Neurotoxicity. To

1. When producing and using organic solvents, it is necessary to strengthen airtightness and ventilation to reduce the escape and evaporation of organic solvents.

2. The use of automation and mechanized operations to reduce the opportunity for direct contact with the operator.

3. use

Organic solvents are a large class of organic compounds that are widely used in daily life and production. They have a small molecular weight and are liquid at room temperature. Organic solvents include many types of substances, such as paraffins, olefins, alcohols, aldehydes, amines, esters, ethers, ketones, aromatic hydrocarbons, hydrogenated hydrocarbons, terpene olefins, halogenated hydrocarbons, heterocyclic compounds, nitrogen compounds and sulfur compounds Etc., most of them are toxic to human body.

I. Hydrocarbon solvents

Organic compounds containing only two elements of hydrocarbons are called hydrocarbons. Hydrocarbons are classified into aliphatic hydrocarbons and aromatic hydrocarbons according to their structure. Aliphatic hydrocarbons include aliphatic hydrocarbons and alicyclic hydrocarbons. Aliphatic hydrocarbons with an open chain structure are classified into saturated hydrocarbons (alkanes) and unsaturated hydrocarbons (olefins and alkynes) according to the degree of structural saturation. Aromatic hydrocarbons are hydrocarbons containing a special structure of a benzene ring. According to the specific structure, it is divided into monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons and fused aromatic hydrocarbons.

Hydrocarbon solvents are divided into two categories according to their source: hydrocarbon mixture solvents obtained from petroleum fractionation are called petroleum spirits, or solvent oils for short; and single hydrocarbon solvents, which are components obtained from the synthesis or refining of chemical raw materials, are pure solvents for hydrocarbons. Pure solvents are expensive and are usually used only for special applications.

Solvent oil

Petroleum is a mixture of a variety of hydrocarbons. After fractional distillation, products with different boiling points are obtained. According to boiling, the radon range usually divides petroleum products into petroleum ether, gasoline, kerosene, diesel, lubricating oil, paraffin and asphalt.

Hydrocarbon pure solvents

The pure hydrocarbon solvents obtained from chemical raw materials mainly include hexane, benzene, toluene, xylene and the like.

Second, alcohol solvents

Organic compounds in which aliphatic hydrocarbon groups are directly connected to hydroxyl groups in the molecule belong to alcohols. It is divided into monohydric and polyhydric alcohols based on the number of hydroxyl groups contained in the molecule. The structure contains benzene or benzene homologs, and the hydroxyl group is not directly connected to the benzene ring is an aromatic alcohol. There are three main types of alcoholic organic solvents used in cleaning.

1. Water-soluble monohydric alcohol solvent

It is the most commonly used alcohol solvent in cleaning, such as methanol, ethanol, isopropanol and other water-soluble monohydric alcohol solvents. It is a flammable and strong hydrophilic solvent. It can be miscible with water at any ratio. It can be an anhydrous or aqueous solvent. Their high-concentration aqueous solutions have a high solubility for oily substances, so they are used to remove rosin flux on electronic printed circuit boards. Another feature of them is that they have strong dissolving power to surfactants, so they are often used to remove the residual adsorption film formed by surfactants on the surface of laundry. This is also a special use for alcohol solvents such as ethanol. Because the water-soluble monoalcohol solvent has a strong binding force with water, when water needs to be replaced from the surface wetted by it, the alcohol solvent is most suitable, among which ethanol and isopropanol are the most widely used. However, alcohol and water will form a constant boiling mixture, so it is not feasible to recover anhydrous and alcohol from the aqueous ethanol solution by ordinary distillation. In addition, high-concentration aqueous solutions of these alcohols have strong sterilization capabilities. Among the three monohydric alcohols that are used more, because methanol has a poor ability to dissolve oily dirt and has strong toxicity, if a person drinks 10cm3 of methanol, it will cause blindness in the eyes, and excessive drinking will cause death. Very toxic substances, so the range of methanol used in cleaning is relatively narrow. Ethanol is a low-toxic alcohol, which is easily biodegraded and has less environmental pollution. It is the most commonly used monohydric alcohol solvent. Compared with methyl and ethanol, isopropyl alcohol has a stronger degreasing ability.

2. Low water-soluble monohydric alcohol solvent

As the number of carbon atoms in monohydric alcohols increases, their boiling points rise and their water solubility gradually decreases. At the same time, their lipophilicity gradually increases, and their ability to dissolve oily substances such as resins gradually increases. So low water-soluble alcohols are often used to remove oily soils. The monohydric alcohol solvents used for cleaning are mainly n-butanol, cyclohexanol and benzyl alcohol.

The characteristics of commonly used low water-soluble monohydric alcohol solvents are as follows.

Butanol is a mixture of various isomers for cleaning. The main component is n-butanol. It is a solvent with both hydrophilicity and lipophilicity. It can be used in 100g of water. Dissolves 7.9 m-butanol, which has a greater affinity for oily soils than ethanol. It can be used as a solvent alone or mixed with a hydrophilic solvent or a lipophilic solvent for various cleaning occasions.

Cyclohexanol is also a solvent with a wide range of solubility for polar organic substances. It has both hydrophilicity and lipophilicity, and its lipophilicity is stronger than that of butanol. Because it has certain emulsification and solubilization when mixed with water, it can also be mixed with water and used.

Benzyl alcohol is a kind of alcohol which is hard to dissolve in water, and it has a strong ability to dissolve polar organic compounds.

2,2,3,3,3-Pentafluoropropanol is a newly developed fluorinated monohydric alcohol. It is a low-water-active 'hydrin alcohol used for cleaning. Because it can be used as a solvent for the synthesis of chlorofluorocarbons, such as CFC- 113) 'Alternative solvents have attracted attention.

Terpineol (terpineol) is a low-water-soluble monohydric alcohol extracted from plants and containing 10 carbon atoms in the molecule. It has four isomers. Terpineol sold as a commercial product is a mixture of various isomers of terpineol and contains other hydrocarbons. It is a five-color viscous liquid or a five-color transparent low-solubility solid. Its performance in dissolving organic matter is similar to pine oil; it has excellent foaming and emulsifying properties, and is often used as a special purpose emulsifying detergent.

3 Polyol solvents

Its solubility is similar to that of monohydric alcohols. The larger the proportion of hydroxyl groups in a molecule, the stronger the hydrophilicity. The most important representative of polyol solvents is ethylene glycol, which is a five-colored, slightly sweet, viscous liquid that is miscible with water in any ratio. It is an excellent solvent. Compared with ethylene glycol, propylene glycol in polyols has a lower lipophilicity due to the lower proportion of hydroxyl groups in the entire molecule. Because it has almost no toxicity, it is often used to remove aviation kerosene used on aircraft. Agent. Various ethers derived from ethylene glycol, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and ethylene glycol mono-n-butyl ether, are very good organic solvents. Among them, ethylene glycol monoethyl ether is commonly known as cellosolve, and they have a strong ability to dissolve polymer resins. Therefore: In addition to being a general cleaning solvent, it is often used as the main raw material for paint strippers. However, due to their strong toxicity, special care must be taken when using them.

Three, ketone solvents

The ketone solvents used in cleaning are mainly acetone and methyl ethyl ketone (2-butanone). Acetone has a molecular formula of C ₃ H ₆ 0. It is a water-soluble lipophilic solvent. It is a solvent with a wide range of solubility. It has the ability to dissolve many organic substances and has low toxicity, so it is widely used as a cleaning solvent. However, the flash point is low and it is a fusible solvent. Pay special attention to safety when using it. Methyl ethyl ketone (2-butanone) has a molecular formula of C ₄ H ₈ 0 and is a ketone solvent with high solubility in oily organics. In addition to being a general washing solvent, it is mainly used as a main component of a solvent for removing a polymer resin on the surface of an object, and is more toxic than acetone.

Fourth, ester solvents

There are many types of ester solvents for cleaning. Commonly used are methyl acetate, ethyl acetate, and n-propyl acetate. The ester solvents are characterized by low toxicity, aromatic odor, insoluble in water, and are mostly used as solvents for oily organics. However, it lacks characteristics as a cleaning solvent. Methyl acetate, ethyl acetate.

Five, phenolic solvents

Phenolic solvents include phenol and cresol. They are slightly acidic organic compounds with relatively high melting points, which are highly toxic. They are mainly used as bactericides and disinfectants. Cresol as a solvent is a mixture of ortho, meta, and p-cresol including three isomers. The application range of phenols as solvents is relatively narrow, but it has unique performance as a coke removal solvent on automobiles and aircraft engines. ^[2]

Commonly used non-polar solvents:

There are chloroform, benzene, liquid paraffin, vegetable oil, ether and so on. Soluble substances such as iodine, bromine ...

Common polar solvents:

Water, formamide, methanol, ethanol, propanol and other materials that can be dissolved. ^[3]