An organochlorine compound, chlorocarbon or chlorinated hydrocarbon, is an organic substance containing at least one covalently bonded chlorine atom that affects the chemical behavior of the molecule. The class of chloroalkanes (alkanes with one or more hydrogen atoms replaced by chlorine) provides general examples. The wide structural diversity and different chemical properties of organochlorines lead to a wide range of names and applications. Organochlorides are very useful substances in many applications, but some of them pose a serious environmental problem.
Influence on properties
Chlorination changes the physical properties of hydrocarbons in several ways. Compounds tend to be denser than water due to the higher atomic weight of chlorine compared to hydrogen. Aliphatic organochlorides are alkylating agents because the chloride is the leaving group.
Determination of organochlorine compounds
Many of these compounds have been isolated from natural sources, from bacteria to humans. Chlorinated organic compounds are found in almost every class of biomolecules, including alkaloids, terpenes, amino acids, flavonoids, steroids, and fatty acids. Organochlorides, including dioxins, form in the high-temperature environment of wildfires, and dioxins have been found in the preserved ash from lightning fires that predated synthetic dioxins.
In addition, various simple chlorinated hydrocarbons, including dichloromethane, chloroform and carbon tetrachloride, have been isolated from seaweed. Most of the chloromethane in the environment is formed naturally through biodegradation, forest fires and volcanoes. Organochlorine compounds in oil are also widely known (according to GOST - R 52247-2004).
Epibatidine
Natural organochlorine epibatidine, an alkaloid isolated from tree frogs, has a strong analgesic effect and stimulates research into new pain medications. Frogs get epibatidine through their food and then isolate it on their skin. Likely food sources are beetles, ants, mites and flies.
Alkanes
Alkanes and arylalkanes can be chlorinated under free radical conditions with ultraviolet radiation. However, the degree of chlorination is difficult to control. Aryl chlorides can be prepared by Friedel-Crafts halogenation using chlorine and a Lewis acid catalyst. Methods for determining organochlorinecompounds include including the use of this catalyst. Other methods are also mentioned in the article.
The haloform reaction using chlorine and sodium hydroxide is also capable of generating alkyl halides from methyl ketones and related compounds. Chloroform was previously produced this way.
Chlorine adds alkenes and alkynes to multiple bonds, giving di- or tetrachloro compounds.
Alkyl chlorides
Alkyl chlorides are versatile building blocks in organic chemistry. Although alkyl bromides and iodides are more reactive, alkyl chlorides are less expensive and more readily available. Alkyl chlorides are easily attacked by nucleophiles.
Heating alkyl halides with sodium hydroxide or water gives alcohols. Reaction with alkoxides or aroxides gives esters in the Williamson ether synthesis; reactions with thiols give thioethers. Alkyl chlorides readily react with amines to form substituted amines. Alkyl chlorides are replaced by softer halides such as iodide in the Finkelstein reaction.
Reaction with other pseudohalides such as azide, cyanide and thiocyanate is also possible. In the presence of a strong base, alkyl chlorides undergo dehydrohalogenation to form alkenes or alkynes.
Alkyl chlorides react with magnesium to form Grignard reagents, converting an electrophilic compound into a nucleophilic one. The Wurtz reaction combines two alkyl halides with sodium in a reducing manner.
Application
The biggest applicationorganochlorine chemistry is the production of vinyl chloride. Annual production in 1985 was about 13 billion kilograms, almost all of which was converted to polyvinyl chloride (PVC). Determination of organochlorine compounds (according to GOST) is a process that cannot be done without special standardized equipment.
Most low molecular weight chlorinated hydrocarbons such as chloroform, dichloromethane, dichloroethane and trichloroethane are useful solvents. These solvents tend to be relatively non-polar; therefore they are immiscible with water and are effective in cleaning such as degreasing and dry cleaning. This purification also applies to methods for the determination of organochlorine compounds (oil and other substances are very rich in these compounds).
The most important is dichloromethane, which is mainly used as a solvent. Chloromethane is a precursor to chlorosilanes and silicones. Historically significant but smaller is chloroform, mainly a precursor to chlorodifluoromethane (CHClF2) and tetrafluoroethene, which is used in the manufacture of Teflon.
The two main groups of organochlorine insecticides are substances such as DDT and chlorinated alicyclic solutions. Their mechanism of action is slightly different from organochlorine compounds in oil.
DDT-like compounds
DDT-like substances act on the peripheral nervous system. In the sodium channel of the axon, they prevent gate closure after activation and depolarization.membranes. Sodium ions seep through the nerve membrane and create a destabilizing negative "post potential" with increased nerve excitability. This leakage causes repeated discharges in the neuron, either spontaneously or after a single stimulus.
Chlorinated cyclodienes include aldrin, dieldrin, endrin, heptachlor, chlordane and endosulfan. Duration of exposure from 2 to 8 hours leads to a decrease in the activity of the central nervous system (CNS), followed by irritability, tremors, and then seizures. The mechanism of action is to bind insecticides at the GABA site in the gamma-aminobutyric acid (GABA) chloride ionophore complex, which prevents chloride from entering the nerve.
Other examples include dicofol, mirex, kepon and pentachlorophenol. They can be either hydrophilic or hydrophobic, depending on their molecular structure.
Biphenyls
Polychlorinated biphenyls (PCBs) were once widely used electrical insulators and heat transfer fluids. Their use has generally been discontinued due to he alth concerns. PCBs have been replaced by polybrominated diphenyl ethers (PBDEs), which cause similar toxicity and bioaccumulation problems.
Some types of organochlorine compounds are highly toxic to plants or animals, including humans. Dioxins, produced by burning organic matter in the presence of chlorine, are persistent organic pollutants that pose a hazard when released into the environment, as do some insecticides (such aslike DDT).
For example, DDT, which was widely used for insect control in the mid-20th century, also accumulates in food chains, like its metabolites DDE and DDD, and causes problems with the reproductive system (for example, thinning of eggshells) in some bird species. Some compounds of this type, such as sulfur mustard, nitrogen mustard and lewisite, are even used as chemical weapons due to their toxicity.
Intoxication with organochlorine compounds
However, the presence of chlorine in an organic compound does not provide toxicity. Some organochlorides are considered safe enough for food and drug use. For example, peas and beans contain the natural chlorinated plant hormone 4-chlorindole-3-acetic acid and the sweetener sucralose (Splenda) are widely used in dietary products.
As of 2004, at least 165 organochlorides were approved worldwide for use as pharmaceuticals, including the natural antibiotic vancomycin, the antihistamine loratadine (Claritin), the antidepressant sertraline (Zoloft), the anti-epileptic lamotrigine (Lamictal), and inhalation drugs. anesthetic isoflurane. It is necessary to know these compounds to determine organochlorine compounds in oil (according to GOST).
Scientists' findings
Rachel Carson brought the pesticide toxicity of DDT to the public in her 1962 book Silent Spring. Although many countries have discontinuedthe use of certain types of organochlorine compounds, such as the US DDT ban, persistent DDT, PCBs, and other organochlorine residues, are still found in humans and mammals around the planet, many years after production and use were restricted.
In the Arctic regions, particularly high levels are found in marine mammals. These chemicals are concentrated in mammals and are even found in human breast milk. In some marine mammal species, especially those that produce high-fat milk, males tend to have much higher levels as females reduce concentrations by passing substances on to offspring through lactation. Also, these substances can be found in oil, which is important to consider when determining organochlorine compounds in oil (according to GOST). It usually refers to pesticides, although it can also refer to any compound of this type.
Organochlorine pesticides can be classified according to their molecular structures. Cyclopentadiene pesticides are aliphatic ring structures derived from Pentachlorocyclopentadiene Diels-Alder reactions and include chlordane, nonachlor, heptachlor, heptachlor epoxide, dieldrin, aldrin, endrin, mirex, and kepon. Other subclasses of organochlorine pesticides are the DDT family and hexachlorocyclohexane isomers. All these pesticides have low solubility and volatility and are resistant to degradation processes in the environment. Their toxicity and persistence in the environment have led to theirrestriction or suspension for most uses in the United States.
Pesticides
Organochlorine pesticides are very effective at killing pests, especially insects. But many of these chemical products are perceived negatively by environmental activists and consumers because of one well-known and now banned organochlorine pesticide: dichlorodiphenyltrichoethane, better known as DDT.
Organochlorine pesticides are chemicals with carbon, chlorine and hydrogen. As the US Fish and Wildlife Service explained, chlorine-carbon bonds are particularly strong, which prevents these chemicals from quickly breaking down or dissolving in water. The chemical also attracts fat and accumulates in the fatty tissue of animals that consume it.
The chemical longevity of organochlorine pesticides is one of the reasons why it is as effective as an insecticide and potentially harmful - it can protect crops for a long time, but can also remain in the body of an animal.
Along with DDT, the US EPA has banned the use of other organochlorine pesticides such as aldrin, dieldrin, heptachlor, mirex, chlordecone and chlordane. Europe has similarly banned many organochlorine pesticides, but in both these regions, organochlorine chemicals are still active ingredients in a number of home, garden and environmental pest control products.environment, according to the EPA. Organochlorine pesticides are also extremely popular in developing countries around the world for agricultural use.
Whether you're surveying farmland to make sure it's still filled with summer organochlorine pesticides, or checking water for organochlorine compounds, testing is the best way to find out if these chemicals are near you. EPA methods 8250A and 8270B can be used to test these chemicals. The 8250A can test waste, soil and water, while the 8270B uses gas chromatography/mass spectrometry (GC/MS).
Although organochlorine pesticides are best known for damaging the ability of some birds to lay he althy eggs, these chemicals are known to adversely affect humans who consume or inhale pesticides. Accidental inhalation or consumption of contaminated fish or animal tissue is the most likely route of ingestion of organochlorine pesticides. To confirm that someone has signs of organochlorine poisoning, blood or urine is usually sent to a university or government agency that uses GC/MS to test for chemical compounds.
Signs of poisoning
Warning signs of organochlorine pesticide toxicity include seizures, hallucinations, cough, skin rash, vomiting, abdominal pain, headaches, confusion and possibly respiratoryinsufficiency according to Matthew Wong, PhD, PhD, and Beth Israel Deaconess Medical Center, Medscape. Although there are bans on many of these pesticides in the US and Europe, their use in other parts of the world and storage in parts of the US and Europe create situations where organochlorine poisoning is still possible.
Organochlorine pesticides include a large number of persistent chemicals that are both effective and carry significant risk worldwide.
Although halogenated organic compounds are relatively rare in nature compared to non-halogenated ones, many such compounds have been isolated from natural sources, from bacteria to humans. There are examples of natural chlorine compounds found in almost every class of biomolecules, including alkaloids, terpenes, amino acids, flavonoids, steroids, and fatty acids.
Organochlorides, including dioxins, form in the high-temperature environment of forest fires, and dioxins have been found in the preserved ash of lightning fires that preceded synthetic dioxins. In addition, various simple chlorinated hydrocarbons, including dichloromethane, chloroform, and carbon tetrachloride, have been isolated from seaweed.
Most of the chloromethane in the environment is produced naturally by biodegradation, forest fires and volcanoes. Natural organochlorine epibatidine, an alkaloid isolated from tree frogs, has a strong analgesic effect andstimulates research into new pain medications.
Dioxins
Some types of organochlorine compounds are highly toxic to plants or animals, including humans. Dioxins, formed when organic matter is burned in the presence of chlorine, and some insecticides, such as DDT, are persistent organic pollutants that pose environmental hazards. For example, the overuse of DDT in the mid-twentieth century, which accumulates in animals, has led to severe declines in some bird populations. Chlorinated solvents, if mishandled and disposed of, create groundwater pollution problems.
Some organochlorides, such as phosgene, have even been used as chemical warfare agents. Some of the artificially created and toxic organochlorides, such as DDT, will build up in the body with each exposure, eventually leading to lethal amounts because the body cannot break them down or get rid of them. However, the presence of chlorine in an organic compound in no way ensures toxicity. Many organochlorine compounds are safe enough for food and drug use.
For example, peas and beans contain the natural chlorinated plant hormone 4-chlorindole-3-acetic acid (4-Cl-IAA) and the sweetener sucralose (Splenda) are widely used in dietary products. As of 2004, at least 165organochlorine compounds for use as pharmaceuticals, including the antihistamine loratadine (Claritin), the antidepressant sertraline (Zoloft), the antiepileptic lamotrigine (lamiktal), and the inhalational anesthetic isoflurane.
Opening Rachel Carson
With Silent Spring (1962), Rachel Carson drew public attention to the problem of organochlorine toxicity. While many countries have phased out the use of some types of these compounds (such as the US ban on DDT as a result of Carson's work), persistent organochlorides continue to be observed in humans and mammals around the planet at potentially harmful levels many years after production. Their use has been restricted.
Organochlorine compounds (according to GOST) are included in the list of substances hazardous to humans.
