Solvents are liquids that are used to dissolve all sorts of substances, usually solid. All solvents are divided into two types: organic and inorganic. Inorganic solvents include water, which is a versatile solvent. Organic solvents are not as versatile, since each of them dissolves a certain amount of solid and liquid elements.
A solvent is a liquid in which one or more substances - solutes - are introduced so as to form a homogeneous phase: a solution. Thus, the solvent is not determined by its chemical structure, but by its physical state - the liquid state - and the use that is made of it. Thus, there is an infinite variety of solvents: water, organic compounds that are simple and liquid at room temperature, are the most common but condensed or pressurized gases such as ammonia or carbon dioxide and molten salts are also used as solvents.
There are many organic compounds that are used as solvents. The most popular among them:
- Hydrocarbons: white spirit, kerosene, gasoline, toluene, petroleum ether, propas and others;
- Alcohols: aniline, dimethyliman, ethyliman;
- Ketones: methylethylekone, acetone and others;
- Esters: amyl acetate, ethyl acetate;
- Organochlorine compounds: chloroform, dichloroethane;
- Nitrogen-containing compounds: nitrobenzene, nitromethane and others.
Also, all kinds of solvent mixtures can often be used. Many organic solvents are volatile and flammable and therefore form explosive mixtures with air. In addition, almost all of them are toxic and poisonous.
Reactive media and extracts in industry, carriers for the transport and use of paints, inks, perfumes, aerosols, cleaning agents, solvents have invaded all activities; therefore they are accused of many contamination cases. However, with more specific and more controlled use, recycling operations make them more careful while expanding their role, over time are still irreplaceable.
Physical properties lead to the first difference between molecular solvents and ionized solvents. Organic compounds are, like water, molecular solvents: they consist of electrically neutral molecules and have low conductivity in their pure form. Ionized solvents are formed mainly from anions and cations connected by electrostatic attractions and are good conductors: molten salts.
Use of organic solvents
Organic solvents are actively used in all kinds of spheres, be it industry, production of paints and varnishes, textiles, plastics, medicine, Agriculture and much more.
In paint and varnish production, they are used to create a working viscosity in various finishing materials: putties, primers and varnishes. Among other things, organic solvents are used to wash equipment and workers' hands.
Molecular solvents are usually classified by the value of their dielectric constant and the dipole moment of their molecule, which determine both the nature of the species that can dissolve in it and the way the dissolved solvent interacts.
A mixture of two or three volumes of concentrated hydrochloric acid and one volume of concentrated nitric acid. Ink is a liquid or paste formulation, black or color, for writing, drawing or printing. They have been produced for centuries according to empirical recipes using natural substances.
Thanks to turpentine, you can significantly speed up the drying process of oil coatings. It also dissolves phosphorus, wax, sulfur. White spirit learns from the distillation of oil and is an intermediate substance between kerosene and gasoline.
Benzene may contain xylene and toluene in its composition. This substance is insoluble in water and flammable. May form explosive mixtures with air. It is also toxic, possesses poisonous vapors, perfectly dissolves camphor, rubber, rosin.
Liquid mixtures consisting of a pigment in a suspension medium and forming a hard film that protects or decorates the surface of wood, metal, stone, leather, paper or fabric. The binder that forms the film hardens and dries the paint. Give some laboratory methods for extracting chemicals from solvent. Two types of extraction: extraction of liquid from liquid and extraction of solid matter dissolved in liquid. Provide definitions of terms related to these operations. Emphasize experimental aspects.
One of the important challenges facing the chemist is knowing how to extract the chemicals he wants from the reaction medium. There is not a universal recipe, but methods that must be applied if necessary. Extraction of a liquid from a solvent.
Bottled alcohol is an excellent solvent for various types of varnishes. This improves their spillage.
Ethylene glycol is an excellent solvent for nitrocellulose. It has a low evaporation rate, which is extremely important for nitro varnishes. As a result, the film comes out smooth, shiny and easy to polish.
Ethyl alcohol as a solvent has a wide range of uses in pharmaceutical technologies, usually for the production of all kinds of solutions for external and internal use. It is also quite often used in the manufacture of injectable medicines. Alcohol solutions, which have a mass fraction of alcohol of about fifteen to twenty percent, have bactericidal properties, thanks to which they can be used to disinfect pharmaceutical dishes, hands and instruments for surgery. In pharmacology, alcohol is a representative of a whole group of narcotic substances. The ethyl alcohol solution should be stored in carefully sealed bottles in a dark, cool place away from fire.
Miscibility between two solids is their ability to mix. For example, water and oil do not mix. On the other hand, some chemical species have more affinity for one solvent than another. For example, an aqueous solution of a dioid is available. This chemical species tinted the solution brown yellow. Cyclohexane, which is an organic solvent, is added.
In general, an organic solvent is composed of molecules formed from a carbon chain. The mixture is poured into a separatory funnel. The mixture is stirred and left to stand. Since cyclohexane is not a polar molecule, its miscibility with water is zero. Thus, we mark the emergence of two very different phases. Sometimes the addition of certain chemicals can increase the separation. Cyclohexane forms an organic phase and water an aqueous phase.
A substance such as glycerin is used to make medicines. It dissolves tannin, sulfate, anesthesin and other substances well. Glycerin does not dissolve in fatty oils and ether, but at the same time, it can be mixed with water and ethanol.
Organic solvents are also actively used in dry cleaners, and in order to remove all kinds of stains from clothes.
Density of a body is its density divided by the density of water. Water has, by definition, the density of cyclohexane, which has a density of 0. Thus, cyclohexane is the highest phase, water will be placed under it. We do not yet know all the organic and mental consequences of these excesses.
My boss probably won't talk anymore. It seems to recognize faces and that's all. It would be beneficial to intelligent organic improvement, one should fear that the intellect has received incurable wounds. A book is essentially an organic thing; it is a part of ourselves.
Organic solvents
Almost all organic solvents are flammable and explosive. In many cases, the danger of their ignition is increased by the high volatility of the solvents. Vapors of highly volatile flammable solvents form explosive mixtures with air, often at room temperature or when the liquid is used above its flash point.
We snatched from the belly a few trophies that we serve the bourgeoisie. Anton. inorganic. Organic diseases. Organic chemistry. The part of chemistry that studies carbon compounds. Organic compounds. Chemical compounds containing carbon. Organic compounds of arsenic.
Anton. Chemical substance. Fertilizers, organic fertilizers; Organic waste. There is beauty in the monuments, great beauty in the organic form of the city, in the progress and movement of its history there is a lot. The tradition of great artistic civilizations is closely associated with progressive discovery and joyful conquest of the organic character of art. Perhaps we are temporarily crossing the era of the masses, after the era of communes, provinces and crafts. But already through this pulsation of the human rhythm, a later period is required, which will restore the articulation of organic societies, without returning to social scales exceeding the speed of movement.
Harmful factors. Most organic solvents are drugs. Almost all organic solvents are poisons of varying degrees of toxicity, which, when ingested, can be poorly detected at first, but later lead to serious consequences. The toxic effect is primarily due to the high dissolving and penetrating ability of organic solvents, which manifests itself in relation to adipose tissues, fiber, blood and lymph. The body's response to a particular solvent is determined by the degree of toxicity of the solvent and the duration of its exposure. This exposure occurs most often through inhaled air contaminated with solvent vapors, but it is possible, as already mentioned, through intact skin. Many solvents (e.g. gasoline, chlorinated hydrocarbons, toluene, xylene) can be absorbed by the skin, enter the bloodstream and cause injury internal organs... The liver and kidneys are often the most affected. Trichlorethylene, toluene, gasoline can cause heart attacks. Gasoline is a known carcinogen, and other solvents, including carbon tetrachloride, chloroform, formaldehyde, are likely carcinogens and should be treated as carcinogens.
In particular. What is the merit of this imperial administration, which is so sorry? What is the merit of the constitution of the state, the treaty? The so-called organic basis is a system of articulatory movements characteristic of a given language, which give it a general phonetic aspect. Regular radiation exposure, even at low doses, can lead to more or less long-term health problems, some of which are irreversible. Priority should be given to replacing hazardous solvents.
There are several thousand solvents, of which one hundred are commonly used. Depending on its properties, the solvent can be used as a degreaser, adjuvant, diluent, stripper, or cleaning agent. For industrial use only organic solvents are used here.
It should be remembered that the restoration of body functions after intoxication may be incomplete due to irreversible damage to some organs. However, up to a certain limit, the body is able to remove harmful substances with exhaled air or remove them in other ways, and use some (for example, ethyl alcohol) as a source of energy. Some of the solvents are converted in the body into less toxic substances. But cumulative toxic substances, which are hardly eliminated from the body and can accumulate in it in dangerous quantities, require particularly stringent preventive measures.
Different situations of using solvents in the company
No solvents are harmless, all of which have health effects that vary with product and occupational exposure, and may be associated with single significant exposures or repeated exposures. Skin diseases, nervous system, blood, liver, kidneys, reproductive or cancer diseases, and the risk of fire and explosion associated with most organic solvents.
Examples of risk exposure
After a hazard assessment, solvents classified and marked as hazardous should be suppressed or replaced, if possible, with lower risk products or processes. Limit the amount of solvents Stored at the workstation in the quantities required for one day's operation. Never wash your hands with solvent. Store waste in specially designed containers. Avoid entering drains.
- Read the label and read the Safety Data Sheet.
- Do not transfer solvent into a vial containing another chemical.
- Limiting losses due to evaporation.
- Perform any suitable operation on a closed system.
According to the degree of toxicity, organic solvents can be classified as follows:
Solvents that must be completely eliminated from use (gasoline, carbon tetrachloride).
Solvents that can only be used under local exhaust ventilation (chloroform, diethyl ether, dimethylformamide, dichloroethane, toluene, trichlorethylene). In general, most aromatic and chlorinated hydrocarbons are considered highly toxic, while most ketones, ethers, alcohols and petroleum distillates are moderately toxic. 3) Solvents, which when necessary control can be considered as relatively slightly toxic substances (acetone, ethyl alcohol).
When paint is applied, the solvent, which is typically 50% by weight of the Paint, evaporates in the working atmosphere and can be inhaled. In the plastics industry, when the molds are changed, the operator cleans them with a cloth soaked in solvent. No gloves, it is exposed to the solvent through the dermal pathway, in all cases it is exposed to solvent vapors which are dried on the mold or on its fabric. Cleaning the molds before cooling increases evaporation and therefore impact. Respiratory tract, cutaneous tract, digestive tract. ... For information on the hazards associated with a particular solvent, the label or MSDS should be consulted first.
In order to work with organic solvents to be safer, it is useful to use the following recommendations: 1. If it is possible to replace a highly toxic solvent with a less toxic one, then this must be done. So, although chlorinated hydrocarbons are distinguished by high dissolving power and reduced flammability, they are considered the most poisonous solvents. Remember that solvents containing chlorinated hydrocarbons can be exposed to heat and ultraviolet rays, which can produce the highly toxic phosgene gas! 2. Always have a respirator with an organic vapor cartridge ready in case the ventilation system fails. 3. Be sure to use funds individual protection... 4. Organic solvents should not be used for cleaning hands and skin in general.
In humans, exposure to high doses of the solvent can result in acute toxicity. Regular irradiation, even at low doses, to one or more solvents can lead to irreversible damage to target organs over a more or less long period. Some effects are common to most solvents, while others are specific to certain substances. Solvents have an affinity for fatty organs.
Risks due to high exposure All organic solvents irritate the skin and mucous membranes to varying degrees. The skin is by no means a barrier to solvents, most of which pass through other sensitive organs. Inhalation of solvent vapors may irritate upper respiratory tract... Inhalation of solvent vapors initially causes ebony-narcotic symptoms and disappears after a few hours. Cardiac chlorinated and fluorinated solvents can disrupt the heart rhythm, resulting in arrhythmias within 48 hours of massive exposure. This kind of effect is very rare in the workplace. Risks due to regular exposure. Contamination of the skin or mucous membranes. Repeated contact with solvents or skin or mucous membranes often results in dermatitis or even contact dermatitis. the protective tissue of the skin can also facilitate the penetration of other toxic substances into the body. Certain glycol ethers and several nitrogenous solvents are also suspected of being hematotoxic to the liver or kidneys. Solvents are partially metabolized by removal of the liver and kidneys, and these organs are preferred targets. Inflammatory lesions of the liver or kidneys have been observed in subjects exposed to polyhalogenated or nitrided solvents. There are also cases of kidney failure in workers who are severely and regularly exposed to solvents. The target organs of the cancer depend on the nature of the solvent. In general, epidemiological studies agree that exposure to high concentrations of solvents can affect fertility, pregnancy, or the fetus. Finally, in humans, certain glycol esters interfere with testicular function.
- Respiratory tract.
- Involvement of the nervous system.
5. During operation, only the amount required for a particular operation should be poured into open containers. If containers with solvents are not needed in this moment, they must be closed with lids.
6. Spent volatile and flammable solutions must not be poured into a sink.
Individual substances
Ammonia water technical NH3, mol. weight 17.03
Properties. Anhydrous ammonia is a colorless gas with a pungent odor. It dissolves well in water, forming a weak alkali - ammonium hydroxide: NH3 + H2O = NH4OH = NH4 + + OH-10% solution of ammonia in water is called ammonia. Commercial concentrated aqueous ammonia solution contains 25% ammonia and has a density of 0.907 g / cc. Water solution ammonia is a slow-burning liquid that is not capable of self-combustion. But in closed spaces above aqueous solutions, explosive mixtures of ammonia with air can form. The lower concentration limit of ammonia in air is 17% by volume, the upper one is 28%. The autoignition temperature of ammonia is 650 ° C. Storage. An aqueous solution of ammonia should be stored in a container with a ground glass stopper, separately from iodine salts! (Iodine nitride, which can be formed in this case, explodes at the slightest touch.) Do not store ammonia together with acids! Action on the body. Aqueous ammonia acts in the same way as gaseous ammonia released from its solutions. In terms of toxicity, it belongs to the 4th hazard class. MPC 20 mg / cubic meter. Has a pronounced irritant effect on mucous membranes and skin. At low concentrations - lacrimation, cough, with large acute eye irritation, chemical burns of mucous membranes, suffocation, pulmonary edema is possible. Safety rules and first aid. Use PPE (filtering industrial gas mask, respirator, overalls, goggles, rubber gloves). In case of ammonia poisoning - Fresh air.
Aniline sulfate (C6H5NH2) H2SO4, mol. weight 284.33 Properties. Crystals or powder of white color with a slight yellowish, grayish or greenish tint. Freshly prepared aniline sulfate -white color... Let's dissolve in water, hardly soluble in alcohol, insoluble in ether. It gets dark in the light and air. Flammable. Dust suspended in air is explosive. Settled dust is fire hazardous. Storage. In dark glass flasks with ground-in corks (for maximum sealing), in a well-ventilated area. Action on the body. A toxic substance that affects the central nervous system and blood. Safety rules and first aid. Work with the substance away from fire. In case of fire, use inert gases, foam fire extinguisher, sand, asbestos blanket for extinguishing. Use PPE when working with aniline sulfate. Do not allow the substance to enter the body, on the skin and mucous membranes. Rinse the affected areas with copious amounts of water.
Acetone СН3СОСН3, mol. weight 58.08 Properties. Transparent colorless volatile liquid with a characteristic odor. Density 0.789-0.791 g / cc. Boiling point 56.2 ° C. Mixes up in any relationship with water, alcohol, ether, dissolves in chloroform. It is a solvent for many organic substances. Acetone is a flammable liquid. Flash point 18 ° С, autoignition temperature 500 ° С (according to GOST 2768-84) and 547 ° С (according to GOST 2603-79). Temperature limits of ignition of vapors: lower 20 ° С, upper 6 ° С.Concentration limits of ignition (by volume): lower 2.2%, upper 13% (according to GOST 2768-84) and, respectively, 2.8 and 11.8 % (according to GOST 2603-79). Acetone is explosive. Explosive concentrations in a mixture with air 2.55-12.8%. Storage. In a cool dry room specially equipped for storing flammable substances. Flasks must be no more than 90% full. The label must indicate: Flammable! Store separately from chlorinated and brominated compounds! Action on the body. Acetone is a toxic liquid that acts like a drug that affects the central nervous system... Belongs to the 4th hazard class. MPC for vapors 200 mg / m3. When inhaled for a long time, it accumulates in the body, penetrating into the bloodstream through the lungs and spreading throughout the body. May cause acute respiratory injury. Acetone can be absorbed in small amounts into the skin. Safety rules and first aid. PPE is used when working with acetone. In case of prolonged contact - skin protection (rubber gloves, rubberized aprons, protective ointments for hands). Beware of using acetone together with substances that can chlorinate or brominate it (formation of poisonous chloro- and bromoacetone is possible!). When pouring, observe the rules of protection against static electricity. Extinguishing media: sand, all types of fire extinguishers. In case of mild poisoning - fresh air, gastric lavage (in case of poisoning - through the mouth).
