Pyrrolidine
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| Surname | Pyrrolidine | ||||||||||||||||||
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| Molecular formula | C 4 H 9 N | ||||||||||||||||||
| Brief description |
colorless liquid with an amine-like odor |
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| properties | |||||||||||||||||||
| Molar mass | 71.12 g mol −1 | ||||||||||||||||||
| Physical state |
liquid |
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| density |
0.86 g cm −3 |
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| Melting point |
−63 ° C |
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| boiling point |
87 ° C |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||||||||
Pyrrolidine ( IUPAC ), also known as azolidine , is an organic-chemical compound from the group of secondary heterocyclic aliphatic amines . It is an important intermediate used in the pharmaceutical and fine chemicals industries.
Occurrence
Pyrrolidine occurs naturally in various types of vegetables (e.g. radishes and pickled peppers ). Some foods such as Tilsiter cheese and luxury foods such as instant coffee can contain pyrrolidine in low concentrations. It forms u. a. easily from the amino acid proline . Pyrrolidine is the main body of the pyrrolidine alkaloids , which are derived either from proline or from ornithine . In addition, pyrrolidine derivatives are also numerous in other natural products , e.g. B. in iminosugars or in polyhydroxy alkaloids as glycosidase inhibitors .
Extraction and presentation
For the industrial production of pyrrolidine, 1,4-butanediol is combined with ammonia at temperatures of 165-220 ° C. and pressures of 170-210 bar in the presence of cobalt and nickel oxide catalysts supported on aluminum oxide (Al 2 O 3 ) , around.
The complete reaction takes place in the liquid phase in a continuous tube or tube bundle reactor which is operated in the gas cycle mode. The catalyst is arranged as a fixed bed and the reaction is carried out in the trickle mode. The product is purified and worked up by multi-stage extractive and azeotropic distillation in rectification columns .
properties
Physical Properties
Pyrrolidine has a relative gas density of 2.45 (density ratio to dry air at the same temperature and pressure ) and a relative density of the vapor-air mixture of 1.09 (density ratio to dry air at 20 ° C and normal pressure ). In addition, pyrrolidine has a vapor pressure of 64.5 hPa at 20 ° C, 107 hPa at 30 ° C, 172 hPa at 40 ° C and 260 hPa at 50 ° C. Furthermore, the dynamic viscosity is 0.94 mPa · s at 20 ° C. According to Antoine, the vapor pressure function results from log 10 (P) = A− (B / (T + C)) (P in kPa, T in K) with A = 6.2, B = 1242 and C = −61 in the temperature range from 296 to 353 K.
Chemical properties
Pyrrolidine is a highly flammable liquid belonging to the group of heterocyclic secondary amines . It is completely miscible with water and easily miscible with most organic solvents . It is also very volatile. The fabric decomposes when exposed to heat. Contact with strong oxidizing agents , chlorinated hydrocarbons , glycol ethers , light metals and phenol can lead to dangerous chemical reactions . Furthermore, pyrrolidine forms carcinogenic nitrosamines with nitrosating agents (e.g. nitrites , nitrous acid , nitrous gases ) . Pyrrolidine reacts as a strong base . An aqueous solution with a concentration of 100 g / l has a pH of 12.9 at a temperature of 20 ° C.
use
Pyrrolidine is a valuable intermediate for numerous applications in the pharmaceutical industry and for the manufacture of fine chemicals . It is the starting material for drugs such as antihistamines or antibiotics . It is also used for the production of fungicides , insecticides , vulcanization accelerators , antioxidants , plasticizers , photo chemicals , dispersants and corrosion inhibitors . It is also a curing agent for epoxy resins and serves as a catalyst for polyurethane production . Pyrrolidine is also used in polymer modification and is used as a template for the production of silica gels or zeolites .
safety instructions
The vapors of pyrrolidine can form explosive mixtures with air when the substance is heated above the flash point. The substance is mainly absorbed through the respiratory tract and the skin . Furthermore, a very effective absorption into the gastrointestinal tract was recognized. In the event of ingestion or exposure , acute irritation and even burns of the skin and mucous membranes occur . Chronic disorders can also occur. Of particular concern is the rapid formation of highly toxic and carcinogenic nitrosamines , which are formed on contact with nitrosating agents. However, a direct mutagenic effect could be ruled out. Insufficient information is available on reproductive toxicity and carcinogenicity . Pyrrolidine has a lower explosion limit (LEL) of approx. 1.6% by volume (48 g / cm 3 ) and an upper explosion limit (UEL) of approx. 10.6% by volume. The ignition temperature is 320 ° C. The substance therefore falls into temperature class T2 and explosion group IIA. With a flash point of 3 ° C, pyrrolidine is considered highly flammable.
Web links
Individual evidence
- ↑ a b c d e f g h i j k l m n o Entry on pyrrolidine in the GESTIS substance database of the IFA , accessed on May 11, 2019(JavaScript required) .
- ↑ a b entry on pyrrolidine. In: Römpp Online . Georg Thieme Verlag, accessed on May 11, 2019 .
- ↑ Entry on pyrrolidines in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on May 11, 2019. Manufacturers or distributors can expand the harmonized classification and labeling .
- ↑ a b Roland Bou Chedid, Johann-Peter Melder, Roman Dostalek, Jörg Pastre, Aik Meam Tan: Process for the production of pyrrolidine. In: Google Patents. BASF SE, June 15, 2016, accessed on May 11, 2019 .
- ^ E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.