Phosphorus(from Greek phosphoros - luminiferous; lat. Phosphorus) P, chemical element of group V of the periodic system; atomic number 15, atomic mass 30.97376. It has one stable nuclide 31 P. The effective cross section for capturing thermal neutrons is 18 10 -30 m 2. External configuration electron shell of atom3 s 2 3p 3 ; oxidation states -3, +3 and +5; energy of sequential ionization during the transition from P 0 to P 5+ (eV): 10.486, 19.76, 30.163, 51.36, 65.02; electron affinity 0.6 eV; Pauling electronegativity 2.10; atomic radius 0.134 nm, ionic radii (coordination numbers are indicated in parentheses) 0.186 nm for P 3-, 0.044 nm (6) for P 3+, 0.017 nm (4 ), 0.029 nm (5), 0.038 nm (6) for P 5+ .

The average phosphorus content in the earth's crust is 0.105% by mass, in waters and oceans 0.07 mg/l. About 200 phosphorus minerals are known. they are all phosphates. Of these, the most important is apatite, which is the basis phosphorites. Also of practical importance are monazite CePO 4 , xenotime YPO 4 , amblygonite LiAlPO 4 (F, OH), triphylline Li(Fe, Mn)PO 4 , torbernite Cu(UO 2) 2 (PO 4) 2 12H 2 O, utunite Ca( UO 2) 2 (PO 4) 2 x x 10H 2 O, vivianite Fe 3 (PO 4) 2 8H 2 O, pyromorphite Pb 5 (PO 4) 3 C1, turquoise CuA1 6 (PO 4) 4 (OH) 8 5H 2 ABOUT.

Properties. It is known that St. 10 modifications of phosphorus, the most important of which are white, red and black phosphorus (technical white phosphorus is called yellow phosphorus). There is no uniform designation system for phosphorus modifications. Some properties of the most important modifications are compared in Table. Crystalline black phosphorus (PI) is thermodynamically stable under normal conditions. White and red phosphorus are metastable, but due to the low rate of transformation they can be preserved for an almost unlimited time under normal conditions.

Phosphorus compounds with nonmetals

Phosphorus and hydrogen in the form of simple substances practically do not interact. Hydrogen derivatives of phosphorus are obtained indirectly, for example:

Ca 3 P 2 + 6HCl = 3CaCl 2 + 2PH 3

Phosphine PH 3 is a colorless, highly toxic gas with the smell of rotten fish. A phosphine molecule can be thought of as an ammonia molecule. However, the angle between the H-P-H bonds is much smaller than that of ammonia. This means a decrease in the share of participation of s-clouds in the formation of hybrid bonds in the case of phosphine. Phosphorus-hydrogen bonds are less strong than nitrogen-hydrogen bonds. The donor properties of phosphine are less pronounced than those of ammonia. The low polarity of the phosphine molecule and weak proton-accepting activity lead to the absence of hydrogen bonds not only in liquid and solid states, but also with water molecules in solutions, as well as to the low stability of the phosphonium ion PH 4 +. The most stable phosphonium salt in the solid state is its iodide PH 4 I. Phosphonium salts vigorously decompose with water and especially alkaline solutions:

PH 4 I + KOH = PH 3 + KI + H 2 O

Phosphine and phosphonium salts are strong reducing agents. In air, phosphine burns to phosphoric acid:

PH 3 + 2O 2 = H 3 PO 4

When phosphides of active metals are decomposed by acids, diphosphine P 2 H 4 is formed simultaneously with phosphine as an impurity. Diphosphine is a colorless volatile liquid, similar in molecular structure to hydrazine, but phosphine does not exhibit basic properties. It ignites spontaneously in air and decomposes when stored in light or when heated. Its breakdown products contain phosphorus, phosphine and a yellow amorphous substance. This product is called solid hydrogen phosphide, and the formula P 12 H 6 is assigned to it.

With halogens, phosphorus forms tri- and pentahalides. These phosphorus derivatives are known for all analogues, but chlorine compounds are practically important. RG 3 and RG 5 are toxic and are obtained directly from simple substances.

RG 3 - stable exothermic compounds; PF 3 is a colorless gas, PCl 3 and PBr 3 are colorless liquids, and PI 3 are red crystals. In the solid state, all trihalides form crystals with a molecular structure. RG 3 and RG 5 are acid-forming compounds:

PI 3 + 3H 2 O = 3HI + H 3 PO 3

Both phosphorus nitrides are known, corresponding to the tri- and pentacovalent states: PN and P 2 N 5 . In both compounds, nitrogen is trivalent. Both nitrides are chemically inert and resistant to water, acids and alkalis.

Molten phosphorus dissolves sulfur well, but the chemical reaction occurs at high temperatures. Of the phosphorus sulfides, P 4 S 3 , P 4 S 7 , and P 4 S 10 are the best studied. These sulfides can be recrystallized in a naphthalene melt and isolated in the form of yellow crystals. When heated, sulfides ignite and burn to form P 2 O 5 and SO 2 . With water they all slowly decompose with the release of hydrogen sulfide and the formation of phosphorus oxygen acids.

Phosphorus compounds with metals

With active metals, phosphorus forms salt-like phosphides, which obey the rules of classical valence. p-Metals, as well as metals of the zinc subgroup, give both normal and anion-rich phosphides. Most of these compounds exhibit semiconductor properties, i.e. the dominant bond in them is covalent. The difference between nitrogen and phosphorus, due to size and energy factors, is most characteristically manifested in the interaction of these elements with transition metals. For nitrogen, when interacting with the latter, the main thing is the formation of metal-like nitrides. Phosphorus also forms metal-like phosphides. Many phosphides, especially those with predominantly covalent bonds, are refractory. Thus, AlP melts at 2197 degrees C, and gallium phosphide has a melting point of 1577 degrees C. Phosphides of alkali and alkaline earth metals are easily decomposed by water, releasing phosphine. Many phosphides are not only semiconductors (AlP, GaP, InP), but also ferromagnets, for example CoP and Fe 3 P.

Phosphine(hydrogen phosphide, phosphorus hydride, according to the IUPAC nomenclature - phosphane PH 3) - a colorless, very toxic, rather unstable gas with a specific smell of rotten fish.

Colorless gas. It dissolves poorly in water and does not react with it. At low temperatures it forms a solid clathrate 8РН 3 ·46Н 2 О. Soluble in benzene, diethyl ether, carbon disulfide. At −133.8 °C it forms crystals with a face-centered cubic lattice.

The phosphine molecule has the shape of a trigonal pyramid with molecular symmetry C 3v (d PH = 0.142 nm, HPH = 93.5 o). The dipole moment is 0.58 D, significantly lower than that of ammonia. The hydrogen bond between PH 3 molecules is practically not observed and therefore phosphine has lower melting and boiling points.

Phosphine is very different from its counterpart ammonia. Its chemical activity is higher than that of ammonia; it is poorly soluble in water, as a base is much weaker than ammonia. The latter is explained by the fact that the H-P bonds are weakly polarized and the activity of the lone pair of electrons in phosphorus (3s 2) is lower than that of nitrogen (2s 2) in ammonia.

In the absence of oxygen, when heated, it decomposes into elements:

spontaneously ignites in air (in the presence of diphosphine vapor or at temperatures above 100 °C):

Shows strong restorative properties:

When interacting with strong proton donors, phosphine can produce phosphonium salts containing the PH 4 + ion (similar to ammonium). Phosphonium salts, colorless crystalline substances, are extremely unstable and easily hydrolyze.

Like phosphine itself, its salts are strong reducing agents.

Phosphine is obtained by reacting white phosphorus with hot alkali, for example:

It can also be obtained by treating phosphides with water or acids:

Synthesis directly from elements is possible:

When heated, hydrogen chloride reacts with white phosphorus:

Decomposition of phosphonium iodide:

Decomposition of phosphonic acid:

or its restoration.

× We have prepared this article in order to help people figure out how to distinguish those who really understand something about fumigating houses from those who are just pretending to do so.

For more than ten years, our company has been successfully fumigating houses with phosphine gas. The methodology itself is directly related to the agricultural industry of storing and processing grains, cereals, dried fruits and other raw materials of plant origin, one way or another used in the food industry. But with one significant difference - the methodology, although agricultural, has been completely reworked by us into modern technology for the specific tasks of exterminating tree pests (bark beetle, longhorned beetle, woodcutter beetle, typographer, etc.) in modern house construction.

At the moment, some companies are trying to copy our proprietary technology. However, not everyone - to say the least - succeeds in this. And therefore, approximately 25%-30% of all our work on fumigation of houses is “remodeling” after those who believe that they know how to do it.

So, you are faced with a problem that you have already identified - the house is infested with a pest. Nowadays, a person immediately opens any search engine and starts looking for companies that can solve this problem. And what does he see? Several dozen (okay, not hundreds!) of different “offices”, many of which are ready to come and do everything within two to three hours.

We won’t explain about smoke, aerosol, fog - we’ve already done that. However, already a couple of years ago, a number of companies appeared that were ready to treat a house with phosphine almost immediately after the call! At the same time, there are not so many specialists who know how to work with phosphine, and there are only a few who also understand house construction. But the number of companies offering this service is still growing!

And how can a non-specialist understand this variety of proposals?

Let's start in order:

ATTENTION! MUST READ!

• If you are offered aerosol treatment, fog treatment is not fumigation with phosphine gas. This type of work also exists, but its cost is significantly lower and the effectiveness is almost zero, since there is no necessary penetration into the wood.

• The cost of fumigation is calculated based on the cubic capacity (volume) of the room, and not its area.

• Not every house can be successfully fumigated from a technical point of view - only a specialist who is well versed not only in fumigation, but also in construction technologies can make a decision about this.

• No house can be successfully fumigated without first preparing it. Preparing a house for fumigation is individual in each case.

• Houses are not fumigated in 3-5 days.

• All work, except preparation, is done by the Contractor. Options like “... in three or four days, come in and ventilate yourself...” - this, at a minimum, is a failure to fulfill one’s obligations. Additionally, for an unprepared person, it can lead to serious, if not fatal, health problems.

• After fumigation, the house is not ventilated, but degassed to the minimum MPC (maximum permissible concentrations). To determine the maximum permissible concentration, special equipment is required.

• Let us emphasize once again that the process of fumigating a house ALWAYS involves two trips - fumigation itself, and after the end of the exposure - degassing. Degassing is not ventilation; it is a separate chemical process, which also includes the disposal of phosphine decomposition products.

• There is no resistance/addiction or immunity of pests to phosphine.

• Phosphine does NOT oxidize silver and gold, but it does oxidize copper. In this case, the metal becomes a little darker, but its properties do not change.

• Phosphine does NOT penetrate polyethylene.

• Phosphine is NOT sprayed by any fumigation machines.

• Concluding a contract without a detailed understanding of the house (at a minimum, photographic materials are required, and even better, a visual inspection) signals the Contractor’s lack of understanding of what he is doing. Or vice versa – about a very “good” understanding of this! With all the consequences...

• A 1-year warranty on work performed is a very controversial condition. Wood pests are usually biennial. If the work is not carried out properly, they may appear again in a year... when the warranty has expired...

Phosphine is a poisonous gas that, in its pure form, is colorless and odorless. From a chemical point of view, it is a volatile hydrogen compound of phosphorus. In chemistry, the formula for phosphine is PH 3. Its properties are similar to ammonia. The substance is very dangerous as it is highly toxic and prone to spontaneous combustion.

Receipt

The most well-studied method for producing phosphine is the reaction of white phosphorus with a strong alkali solution when heated. In this case, phosphorus is disproportionated into metaphosphate and phosphine. The by-products of this reaction are diphosphine (P 2 H 4) and hydrogen, so the yield of this reaction is small and is no more than 40%.

The resulting diphosphine in the reaction medium interacts with an alkali, resulting in the formation of phosphine and hydrogen.

And the hypophosphite obtained in these reactions, when interacting with an alkali, turns into phosphate with the release of hydrogen.

NaH 2 PO 2 + 2NaOH = 2H 2 + Na 3 PO 4

After all reactions are completed, as a result of the interaction of alkali with phosphorus, phosphine, hydrogen and phosphate are formed. This production method can also be carried out with alkali oxides instead of alkalis. This experiment is very beautiful, since the resulting diphosphine immediately ignites and burns in the form of sparks, creating something similar to fireworks.

When metal phosphides are exposed to water or acid, phosphine is also produced.

During the thermal decomposition of phosphorous acid or its reduction with hydrogen, phosphine is also formed at the time of release.

Phosphonium salts, when decomposed or reacted with certain substances, produce phosphine.

Physical properties

Phosphine is a colorless, odorless gas. But technical phosphine (with some impurities) can have a characteristic unpleasant odor, which is described in different ways. Slightly heavier than air, it liquefies at a temperature of -87.42 °C, and becomes a solid at -133.8 °C. Such low boiling and melting points are due to rather weak hydrogen bonds. The substance is practically insoluble in water, but under certain conditions it forms hydrates. Very soluble in ethanol and diethyl ether. The density of phosphine under normal conditions is 0.00153 g/cm 3 .

Chemical properties

As already mentioned, the chemical formula of phosphine is PH 3. Although phosphine is similar to ammonia, it has a number of differences in its interactions with other substances. These features are due to the fact that the chemical bonds in phosphine (this becomes clear from the formula) are covalent, weakly polar. They are less polar than those in ammonia and therefore more durable.

When heated strongly (approximately 450 °C) without access to oxygen, phosphine decomposes into simple substances.

2PH 3 → 2P + 3H 2

At temperatures above 100 °C PH 3 spontaneously ignites, reacting with oxygen in the air. The temperature threshold can be lowered with ultraviolet light. For this reason, phosphine released in swamps often spontaneously ignites, causing the appearance of so-called “will-o’-the-wisps.”

PH 3 + 2O 2 → H 3 PO 4

But simple combustion can also occur. Phosphoric anhydride and water are then formed.

2PH 3 + 4O 2 → P 2 O 5 + 3H 2 O

Like ammonia, phosphine can form salts by reacting with hydrogen halides.

PH 3 + HI→ PH 4 I

PH 3 + HCl→ PH 4 Cl

Based on the formula of phosphine, we can say that the phosphorus in it has the lowest oxidation state. For this reason it is a good reducing agent.

PH 3 + 2I 2 + 2H 2 O → H 3 PO 2 + 4HI

PH 3 + 8HNO 3 → H 3 PO 4 + 8NO 2 + 4H 2 O

Application

Due to its high toxicity, phosphine has found application in fumigation, that is, the destruction of various types of pests (insects, rodents) using gas. For these procedures, there are special devices - fumigation machines, which are used to spray gas in rooms. Typically, warehouses of grain crops, prepared food products, furniture, as well as libraries, factory premises, train cars and other vehicles are treated with phosphine or preparations based on it. The advantage of this treatment is that phosphine, even in small concentrations, easily penetrates hard-to-reach places and does not interact in any way with metals, wood and fabric.

The room is treated with phosphine and kept sealed for 5-7 days. After this, ventilation must be carried out for at least two days, otherwise it is dangerous for a person to be in it. After this, phosphine does not leave any traces even on food, grain and other goods.

Phosphine is also used in the synthesis of certain substances, especially organic ones. Chemically pure phosphorus can also be obtained from it, and semiconductors are doped using phosphine.

Toxicology

Phosphine is an extremely toxic compound. It quickly passes through the respiratory tract and interacts with the mucous membranes of the body. This can cause disruption of the nervous system, as well as metabolism in general. Signs of poisoning can include dizziness, nausea, vomiting, headache, fatigue, and sometimes even convulsions. In severe cases of departure, a person may lose consciousness or stop breathing and heartbeat. The maximum permissible concentration of phosphine in the air is 0.1 mg/m3. A concentration of 10 mg/m3 is immediately fatal.

The first thing to do with a victim of phosphine poisoning is to remove him to fresh air and remove contaminated clothing. It is also recommended to spray the victim with water to quickly remove any remaining toxic gas. Inpatient treatment involves the use of an oxygen mask, monitoring of heart rate and liver condition, and treatment of pulmonary edema. The patient must be monitored for at least 2-3 days, even if there are no longer visible signs of poisoning. Some symptoms may not appear until several days after exposure to phosphine.

As you know, demand for services creates supply, and not all companies approach the services they provide with due responsibility in terms of efficiency and safety. One of the services for which professionalism is extremely important is home fumigation with phosphine gas.

Fumigation with phosphine against bark beetles in a wooden house has many advantages.

It is necessary to keep in mind that fumigation involves a number of different inconveniences, the main ones being:

• Seasonality of work. Fumigation is not performed in a heated room if the heating element (boiler, stove) is located in the same building. This is due to the fact that in large concentrations the gas can be very explosive. Before fumigation, the house is de-energized and the heating is turned off.
• Since fumigation cannot be performed during heating, it is carried out exclusively at positive temperatures from spring to autumn.
• Gas is very dangerous for all living things. All family members must move out during the procedure, the average period is five to seven days. You cannot enter the premises or open doors and windows. This can be very dangerous!
• After complete release of gas, a worker needs to return again to perform degassing; he will collect and dispose of all decomposition products.
• After completion of fumigation, degass the room for at least 4-6 hours!

We conducted our own analysis of the fumigation market, requested documents on the training of specialists, consultations with operators and came to the conclusion that Russia is still far from meeting European standards, but not all is lost.

Preparing a house for fumigation with Phosphine

• Remove all equipment from the house (smartphones, televisions, computers, tablets, smartphones). Household appliances (vacuum cleaners, washing machines) can be left.
• Remove all exposed food.
• Personal hygiene items (combs, toothbrushes).
• Close chimneys, stove pipes, ventilation shafts, and hoods by applying a special patch made of special gas-tight, very high-density polyethylene.
• All cracks, as well as possible places of gas leakage, must be sealed with construction tape, or a special patch made of very high-density polyethylene is applied.
• All plants and animals must be removed from the house.
• Warn neighbors about the upcoming fumigation and the danger of being in the vicinity (less than 10 m) from the house.
• The house must be completely de-energized during fumigation.
• Any heating in the house is turned off during fumigation.

Magtoxin (magnesium phosphide based fumigant)

magtoxin and phostoxin

Magtoxin from Detia Degesch GmbH is a fumigant that consists of magnesium phosphide, paraffin and ammonium carbamate. It is produced in the form of round tablets, as well as pills weighing 3 g and 0.6 g, respectively. When exposed to atmospheric air, the fumigant releases hydrogen phosphide; the rate of release depends on air humidity and temperature.

Magtoxin has excellent insecticidal activity. It penetrates very quickly through any packaging materials, as well as inside sealed goods. Hydrogen phosphide very effectively destroys adult pests of grain stocks (rice and granary weevils, grain sawflies, southern granary moths, nylon beetles, varieties of grain moths), as well as when they are in the stages of pupae, eggs and larvae. Carbon dioxide and ammonia act as special protective gases. Phosphine gas easily penetrates the structure of the tree, into any passages of the beetle and its larvae, leaving them no chance to hide or take cover.

Since Magtoxin decomposes almost completely, the residual dust contains almost no undecomposed metal phosphide, unlike various products that contain aluminum phosphide.

Magtoxin decomposes much faster than products that contain aluminum phosphide. The maximum concentration of hydrogen phosphide released by this fumigant is reached within 24–36 hours. For comparison, over the same time period and under similar conditions (temperature 20°C and humidity 60%), products based on aluminum phosphide release approximately 72% of hydrogen phosphide, while magnesium phosphide is released completely.

Scope of gas use for fumigation

Due to its particular effectiveness, it began to be used for fumigation of wooden houses in case of infection with wood-eating beetles; it does not leave any traces, does not spoil property, rodents and all other insects die along with the beetles. This method simply has no analogues in terms of efficiency.

At the moment, there are a lot of companies on the service market offering their services for phosphine fumigation . We conducted our own “investigation” and analysis of companies and found that 85% of all disinfection services in Moscow are fake. There are no offices, no permits, no trained staff. Or companies create a bunch of websites under different names in order to capture as many potential customers and market share as possible. The only one we found service that meets all our requirements turned out to be the company Dezcenter-Rus.

We selected companies based on several criteria:

• The staff have certificates and certificates of completion of the prof. training including work with pesticides of hazard class 1.
• Availability of prof. equipment and facilities
• Availability of a functioning, real office where you can come
• Membership in NP "NOD" National organization of disinfectionists
• Reviews on the Internet
• Duration of work on the disinfection services market
• Price policy…

The effect of fumigation is highly dependent on a number of factors, such as the type of pest, the gas permeability of the building, humidity, product packaging and temperature. The fumigation time depends entirely on the type of room, as well as its gas tightness. Ventilation time (that is, degassing) is at least 3–6 hours.

Due to the special formulation of Magtoxin, its use guarantees complete safety for the disinfection company employee.

Benefits of Magtoxin

• Quickly and almost completely decomposes.
• Almost does not leave any residues in processed products.
• The residual dust contains almost no undecomposed phosphide.
• Very economical.

Fumigation of a house under a dome

To properly carry out fumigation, it is necessary to achieve the greatest airtightness of the room, which in some situations is simply impossible. The absence of a roof, doors or windows in the house makes fumigation simply impossible. In these situations, a special gas-tight dome is made. It is placed on the selected house according to the “hat” principle. The production of this dome takes from one to three months.

Symptoms of poisoning from phosphine fumigation

Phosphine gas is a highly volatile substance. If special safety measures are not followed, you can very easily get poisoned, even death. Such poisoning is often confused with the flu, food poisoning, or the consequences of drinking alcohol - a hangover.

The main signs of phosphine poisoning:

• Vomiting and nausea.
• Fatigue and depression.
• Muscle pain and cramps, convulsions.
• Migraine and headache.
• Shortness of breath and difficulty breathing.
• Pain in the upper abdomen, as well as chills (milder cases of poisoning).
• Tinnitus, increased intracranial pressure, feeling of fear (moderate phosphine gas poisoning).
• Respiratory and cardiac arrest, loss of consciousness, coma (very severe phosphine gas poisoning).

Symptoms of poisoning may appear two days after poisoning.

Important information

• If you are offered a special aerosol treatment, high-quality fog treatment, then this is not fumigation with phosphine gas. This type of work also exists, but its price is much lower and the effectiveness is almost zero, since there is no necessary penetration into the material.
• The price of fumigation is calculated based on the cubic capacity (that is, volume) of the room, and not at all its area.
• Not every house can be successfully fumigated from a technical point of view - only a specialist who is well versed not only in fumigation, but also in various construction technologies can make a decision about this.
• No house can be successfully fumigated without special preliminary preparation. Preparing housing for fumigation is individual in each individual case.
• Currently, houses are not fumigated within three days.
• All the work, in addition to preparation, is done by the performer. Options like “... in three days, come in yourself and air everything out...” - at a minimum, this is not fulfilling one’s own obligations. In addition, for an unprepared person, this could very well lead to very serious, if not fatal, health problems.
• After fumigation, the house is not ventilated, but special degassing is carried out to the minimum maximum permissible concentrations (that is, maximum permissible concentrations). To determine this parameter, special equipment is required.
• Phosphine is not able to penetrate polyethylene.
• Phosphine is not sprayed by fumigation machines.
• Once again, it is important to note that the process of fumigating a house in any case involves two trips - this is the fumigation itself, and after the end of the exposure - degassing. Degassing is not ventilation at all, but a separate chemical procedure, which also includes the disposal of all phosphine decomposition products.
• Resistance, that is, addiction, or immunity to phosphine in pests simply does not exist.
• Phosphine does not oxidize gold and silver, but easily oxidizes copper. In this case, the metal immediately becomes a little darker, but its properties and qualities do not change.
• Entering into an agreement without a detailed understanding of the home (at a minimum, photographs are required, and even better, a full visual inspection) indicates a lack of understanding on the part of the company of what it is doing. Or vice versa – about a very “good” understanding of all this! And with all the consequences...

How much does phosphine fumigation cost?