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Paraldehyde
Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane, with a methyl group substituted for a hydrogen atom at each carbon. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in ethanol. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of acetic acid. It quickly reacts with most plastics and rubber. Paraldehyde was first observed in 1835 by the German chemist Justus Liebig; its empirical formula was determined in 1838 by Liebig's student Hermann Fehling. The German chemist Valentin Hermann Weidenbusch (1821–1893), another of Liebig's students, synthesized paraldehyde in 1848 by treating acetaldehyde with acid (either sulfuric or nitric acid) and cooling to 0°C. He found it quite remarkable that when paraldehyde was ''heated'' with a trace of the same acid, the reaction went the other way, recreating acetaldehyde. Paraldehyde has uses i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraldehyde Stereochemistry 2
Paraldehyde is the cyclic trimer (chemistry), trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane, with a methyl group substituted for a hydrogen atom at each carbon. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in properties of water, water and highly soluble in ethanol. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of acetic acid. It quickly reacts with most plastics and rubber. Paraldehyde was first observed in 1835 by the German chemist Justus Liebig; its empirical formula was determined in 1838 by Liebig's student Hermann von Fehling, Hermann Fehling. The German chemist Valentin Hermann Weidenbusch (1821–1893), another of Liebig's students, synthesized paraldehyde in 1848 by treating acetaldehyde with acid (either sulfuric or nitric acid) and cooling to 0°C. He found it quite remarkable that when paraldehyde was ''heated'' with a trace of the same acid, the reaction went the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraldehyde Metaldehyde Synthesis
Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane, with a methyl group substituted for a hydrogen atom at each carbon. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in ethanol. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of acetic acid. It quickly reacts with most plastics and rubber. Paraldehyde was first observed in 1835 by the German chemist Justus Liebig; its empirical formula was determined in 1838 by Liebig's student Hermann Fehling. The German chemist Valentin Hermann Weidenbusch (1821–1893), another of Liebig's students, synthesized paraldehyde in 1848 by treating acetaldehyde with acid (either sulfuric or nitric acid) and cooling to 0°C. He found it quite remarkable that when paraldehyde was ''heated'' with a trace of the same acid, the reaction went the other way, recreating acetaldehyde. Paraldehyde has uses in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetaldehyde
Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale in industry. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants. It is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase and is a contributing cause of hangover after alcohol consumption. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke. Consumption of disulfiram inhibits acetaldehyde dehydrogenase, the enzyme responsible for the metabolism of acetaldehyde, thereby causing it to build up in the body. The International Agency for Research on Cancer (IARC) has listed acetaldehyde as a Group 1 carcinogen. Acetaldehyde is "one of the mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anticonvulsant
Anticonvulsants (also known as antiepileptic drugs or recently as antiseizure drugs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder and borderline personality disorder, since many seem to act as mood stabilizers, and for the treatment of neuropathic pain. Anticonvulsants suppress the excessive rapid firing of neurons during seizures. Anticonvulsants also prevent the spread of the seizure within the brain. Conventional antiepileptic drugs may block sodium channels or enhance γ-aminobutyric acid ( GABA) function. Several antiepileptic drugs have multiple or uncertain mechanisms of action. Next to the voltage-gated sodium channels and components of the GABA system, their targets include GABAA receptors, the GAT-1 GABA transporter, and GABA transaminase. Additional targets include voltage-gated calcium channels, SV2A, and α2δ. By blocking sodium or ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metaldehyde
Metaldehyde is an organic compound with the chemical formula, formula (C8H16O4). It is used as a pesticide against slugs, snails, and other gastropods. It is the cyclic tetramer of acetaldehyde. Production and properties Metaldehyde is flammable, toxic if ingested in large quantities, and irritating to the skin and eyes. It has a white crystalline appearance with a menthol odor. Metaldehyde is obtained in moderate yields by treatment of acetaldehyde with various Acid catalysis, acid catalysts, such as hydrogen bromide, and cooling. The liquid trimer, paraldehyde is also obtained. The reaction is reversible; upon heating to about 80 °C, metaldehyde and paraldehyde revert to acetaldehyde. Metaldehyde exists as a mixture of four stereoisomers, molecules that differ with respect to the relative orientation of the methyl groups on the 8-membered ring. The stereoisomers have respectively the molecular symmetries C (with symmetry of order 2), C (order 4), D (order 8), and C ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cough Medicine
Cold medicines are a group of medications taken individually or in combination as a treatment for the symptoms of the common cold and similar conditions of the upper respiratory tract. The term encompasses a broad array of drugs, including analgesics, antihistamines and decongestants, among many others. It also includes drugs which are marketed as cough suppressants or antitussives, but their effectiveness in reducing cough symptoms is unclear or minimal. While they have been used by 10% of American children in any given week, they are not recommended in Canada or the United States in children six years or younger because of lack of evidence showing effect and concerns of harm. In 2020, one version containing codeine and guaifenesin was the 377th most commonly prescribed medication in the United States with more than 400thousand prescriptions. Types There are a number of different cough and cold medications, which may be used for various coughing symptoms. The commercially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypnotic
Hypnotic (from Greek ''Hypnos'', sleep), or soporific drugs, commonly known as sleeping pills, are a class of (and umbrella term for) psychoactive drugs whose primary function is to induce sleep (or surgical anesthesiaWhen used in anesthesia to produce and maintain unconsciousness, "sleep" is metaphorical as there are no regular sleep stages or cyclical natural states; patients rarely recover from anesthesia feeling refreshed and with renewed energy. The word is also used in art.) and to treat insomnia (sleeplessness). This group of drugs is related to sedatives''. ''Whereas the term sedative describes drugs that serve to calm or relieve anxiety, the term hypnotic generally describes drugs whose main purpose is to initiate, sustain, or lengthen sleep. Because these two functions frequently overlap, and because drugs in this class generally produce dose-dependent effects (ranging from anxiolysis to loss of consciousness), they are often referred to collectively as sedative-h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedative
A sedative or tranquilliser is a substance that induces sedation by reducing irritability or excitement. They are CNS depressants and interact with brain activity causing its deceleration. Various kinds of sedatives can be distinguished, but the majority of them affect the neurotransmitter gamma-aminobutyric acid (GABA). In spite of the fact that each sedative acts in its own way, most produce relaxing effects by increasing GABA activity. This group is related to hypnotics. The term ''sedative'' describes drugs that serve to calm or relieve anxiety, whereas the term ''hypnotic'' describes drugs whose main purpose is to initiate, sustain, or lengthen sleep. Because these two functions frequently overlap, and because drugs in this class generally produce dose-dependent effects (ranging from anxiolysis to loss of consciousness) they are often referred to collectively as ''sedative-hypnotic'' drugs. Sedatives can be used to produce an overly-calming effect ( alcohol being the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimer (chemistry)
In chemistry, a trimer (; ) is a molecule or polyatomic anion formed by combination or association of three molecules or ions of the same substance. In technical jargon, a trimer is a kind of oligomer derived from three identical precursors often in competition with polymerization. Examples Alkyne trimerisation In 1866, Marcellin Berthelot reported the first example of cyclotrimerization, the conversion of acetylene to benzene. This process was commercialized: : Nitrile trimerization Symmetrical 1,3,5-triazines are prepared by trimerization of certain nitriles such as cyanogen chloride or cyanimide. Cyanogen chloride and cyanogen bromide each trimerize at elevated temperatures over a carbon catalyst. The chloride gives cyanuric chloride: : The bromide has an extended shelflife when refrigerated. Like the chloride, it undergoes ab exothermic trimerisation to form cyanuric bromide. This reaction is catalyzed by traces of bromine, metal salts, acids and bases. For this reason ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placebo Effect
A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures. In general, placebos can affect how patients perceive their condition and encourage the body's chemical processes for relieving pain and a few other symptoms, but have no impact on the disease itself. Improvements that patients experience after being treated with a placebo can also be due to unrelated factors, such as regression to the mean (a statistical effect where an unusually high or low measurement is likely to be followed by a less extreme one). The use of placebos in clinical medicine raises ethical concerns, especially if they are disguised as an active treatment, as this introduces dishonesty into the doctor–patient relationship and bypasses informed consent. While it was once assumed that this deception was necessary for placebos to have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depressant
A depressant, or central depressant, is a drug that lowers neurotransmission levels, which is to depress or reduce arousal or stimulation, in various areas of the brain. Depressants are also colloquially referred to as downers as they lower the level of arousal when taken. Stimulants or "uppers" increase mental or physical function, hence the opposite drug class of depressants is stimulants, not antidepressants. Depressants are widely used throughout the world as prescription medicines and as illicit substances. Alcohol is a very prominent depressant. Alcohol can be and is more likely to be a large problem among teenagers and young adults. When depressants are used, effects often include ataxia, anxiolysis, pain relief, sedation or somnolence, and cognitive or memory impairment, as well as in some instances, euphoria, dissociation, muscle relaxation, lowered blood pressure or heart rate, respiratory depression, and anticonvulsant effects. Depressants also act to produce anes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Bodkin Adams
John Bodkin Adams (21 January 18994 July 1983) was an Irish-born British general practitioner, convicted fraudster, and suspected serial killer. Between 1946 and 1956, 163 of his patients died while in comas, which was deemed to be worthy of investigation. In addition, 132 out of 310 patients had left Adams money or items in their wills. Adams was tried and acquitted for the murder of one patient in 1957, while another count of murder was withdrawn by the prosecution in what was later described as "an abuse of process" by the presiding judge Patrick Devlin, Baron Devlin, causing questions to be asked in Parliament of the United Kingdom about the prosecution's handling of events. Adams was found guilty in a subsequent trial of thirteen offences of prescription drug fraud, lying on cremation forms, obstruction of justice during a police search, and failing to keep a dangerous drugs register. He was struck off by the General Medical Council in 1957 and reinstated in 1961 after two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
