1.a colorless liquid (a cyclic trimer of acetaldehyde) that is used as a sedative and a solvent
1.(MeSH)A hypnotic and sedative with anticonvulsant effects. However, because of the hazards associated with its administration, its tendency to react with plastic, and the risks associated with its deterioration, it has largely been superseded by other agents. It is still occasionally used to control status epilepticus resistant to conventional treatment. (From Martindale, The Extra Pharmacopoeia, 30th ed, p608-9)
definition of Wikipedia
Antiepileptics and antiparkinsonism drugs Y46[àLExclusionDe]
alcool non alimentaire (fr)[Classe]
|Jmol-3D images||Image 1|
|Molar mass||132.16 g mol−1|
12 °C, 285 K, 54 °F ()
124 °C, 397 K, 255 °F ()
|Solubility in water||insoluble|
|EU classification||Xn C|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in alcohol. 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 synthesized in 1829 by Wildenbusch. It has uses in industry and medicine.
Theoretically four stereoisomeric structures are possible. The structures (1) and (2) are known as cis- and trans-paraldehyde. The structures (3) (a conformer of (2)) and (4) (a conformer of (1)) don't exist for steric reasons.
Since paraldehyde has better handling characteristics, it may be used indirectly or directly as a synthetic equivalent of anhydrous acetaldehyde (b.p. 20 °C). For example, it is used as-is in the synthesis of bromal (tribromoacetaldehyde):
It is a CNS depressant and was soon found to be an effective anticonvulsant, hypnotic and sedative. It was included in some cough medicines as an expectorant (though there is no known mechanism for this function beyond the placebo effect).
It was commonly used to induce sleep in sufferers from delirium tremens but has been replaced by other drugs in this regard. It is one of the safest hypnotics and was regularly given at bedtime in psychiatric hospitals and geriatric wards up to the 1960s. Up to 30% of the dose is excreted via the lungs (the rest via the liver). This contributes to a strong unpleasant odour on the breath.
Today, paraldehyde is sometimes used to treat status epilepticus. Unlike diazepam and other benzodiazepines, it does not suppress breathing at therapeutic doses and so is safer when no resuscitation facilities exist or when the patient's breathing is already compromised. This makes it a useful emergency medication for parents and other caretakers of children with epilepsy. Since the dose margin between the anticonvulsant and hypnotic effect is small, paraldehyde treatment usually results in sleep.
Generic paraldehyde is available in 5ml sealed glass ampoules. Production in the US has been discontinued, but it was previously marketed as Paral.
Paraldehyde has been given orally, rectally, intravenously and by intramuscular injection. It reacts with rubber and plastic which limits the time it may safely be kept in contact with some syringes or tubing before administration.
Dictionary and translator for handheld
New : sensagent is now available on your handheld
A windows (pop-into) of information (full-content of Sensagent) triggered by double-clicking any word on your webpage. Give contextual explanation and translation from your sites !
With a SensagentBox, visitors to your site can access reliable information on over 5 million pages provided by Sensagent.com. Choose the design that fits your site.
Improve your site content
Add new content to your site from Sensagent by XML.
Crawl products or adds
Get XML access to reach the best products.
Index images and define metadata
Get XML access to fix the meaning of your metadata.
Please, email us to describe your idea.
Lettris is a curious tetris-clone game where all the bricks have the same square shape but different content. Each square carries a letter. To make squares disappear and save space for other squares you have to assemble English words (left, right, up, down) from the falling squares.
Boggle gives you 3 minutes to find as many words (3 letters or more) as you can in a grid of 16 letters. You can also try the grid of 16 letters. Letters must be adjacent and longer words score better. See if you can get into the grid Hall of Fame !
Change the target language to find translations.
Tips: browse the semantic fields (see From ideas to words) in two languages to learn more.