2-Pyrrolidone,

Penetration enhancer plasticizer solvent solubilizing agent. 

Pyrrolidones such as 2-pyrrolidone and N-methylpyrrolidone see Section 17) are mainly used as solvents in veterinary injections. They have also been suggested for use in human pharmaceutical formulations as solvents in parenteral, oral, and topical applications. In topical applications, pyrrolidones appear to be effective penetration enhancers. Pyrrolidones have also been investigated for their application in controlled-release depot formulations.  

2-Pyrrolidone occurs as a colorless or slightly colored liquid that solidifies at room temperature and has a characteristic odor. 

Dipole moment 2.3 Debye at 25°C Enthalpy of vaporization 48.21 3.0kJ/mol Flash point (open cup) 54°C Melting point 2.6°C Refractive index = 1.480-1.490 

Solubility miscible with ethanol (95%), propan-2-ol, and water. Also miscible with other organic solvents such as aromatic hydrocarbons. 

Wahrend 4-Hydroximino-4-pyridyl-(2)-butansaure-athylester liber Palladium/Ba-riumsulfat zum 5-Pyridyl-(2)-pyrrolidon-(2) hydriert wird2, bleibt die Hydroximino-Gruppe bei der RingschluBhydrierung des 2-Hydroximino-3-phenyl-3-cyan-propansau-re-athylesters zum 3-Hydroximino-4-phenyl-pyrrolidon-(2) liber Platin(IV)-oxid in Eis-essig selektiv erhalten3. 

4-Dibenzylamino-carbonsaureester werden lediglich unter Monodebenzylierung zu 1 -Benzyl-pyrrolidonen-(2) hydriert4 (S.468). Selektiv wird 4-(Athoxycarbonyl-hy-drazono)-pentansaure mit Platin(IV)-oxid zum 1 -Athoxycarbonylamino-5-methyl-2-pyr-rolidon (81% d.Th.) hydriert (eine Hydrogenolyse der N-N-Bindung wird nicht beobach-tet)  

4-Oxo-pentansaure und deren Ester konnen im Eintopfverfahren mit Ammoniak6, primaren Aminen7 8 oder Amino-alkoholen9 durch reduktive Aminierung und nachfol-gende Kondensation zu5-Methyl-2-pyrrolidonen in Ausbeuten von 63—95%d.Th. umge-setzt werden. 

Kondensierte 2-Pyrrolidone erhalt man aus 2-Nitro-phenylessigsauren die Lactam-Bildung des zunachst erhaltenen Amins tritt zumeist bereits bei 20° ein11. 

Die reduktive Cyclisierung der 3-[Chinoxalinyl-(2)]-propensaure zum 1-Oxo-l,2,3,3a,4,5-hexahydro-(pyrrolo-[l, 2-a]-chinolaxin) setzt die Bildung eines se-kundaren cyclischen Amins voraus, die unter milden Bedingungen mit Raney-Nickel (100 Gew.% bez. auf das Substrat) gelingt12. 

As shipped, 2-PYROL meets a specification of 98 5% minimum purity, 0.5% maximum moisture. 

Physical form liquid with mild amine-like odor  

---

HOCH2CH2CH2CH2OH. B.p. 228"C. Prepared ethyne plus methanal, hydrogenated to butanediol. Used in production of y-buty-rolactone and 2-pyrrolidone. Widely used in polyurethane products, butylenes See butenes. 

N-methyl-2-pyrrolidone Biodegradable solvent particularly for resins. 

The introduction of monomers containing polar groups such as tertiary amines, imidazoles, pyrrolidones, pyridines, etc., gives the polymer dispersant properties that will be discussed in the article on dispersant additives for lubricants. 

Supplement 1953 3103-3241 Carbonyl compounds a-Pyrrolidone, 236. Tropinone, 259. Succinimide, 369. Isatin, 432. Phthalimide, 458. 

It might be noted that most (not all) alkenes are polymerizable by the chain mechanism involving free-radical intermediates, whereas the carbonyl group is generally not polymerized by the free-radical mechanism. Carbonyl groups and some carbon-carbon double bonds are polymerized by ionic mechanisms. Monomers display far more specificity where the ionic mechanism is involved than with the free-radical mechanism. For example, acrylamide will polymerize through an anionic intermediate but not a cationic one, A -vinyl pyrrolidones by cationic but not anionic intermediates, and halogenated olefins by neither ionic species. In all of these cases free-radical polymerization is possible. 

Poly(vinyl pyrrolidone). Another commercial polymer with significant usage is PVP (7). It was developed ia World War II as a plasma substitute for blood... 

M-Pjrol, N-Methyl-2-Pyrrolidone Handbook, GAP Corp., New York, 1972. 

A/ -Methoxycarbonyl-2-pyrroline undergoes Vilsmeier formylation and Friedel-Crafts acylation in the 3-position (82TL1201). In an attempt to prepare a chloropyrroline by chlorination of 2-pyrrolidone, the product (234) was obtained in 62% yield (8UOC4076). At pH 7, two molecules of 2,3-dihydropyrrole add together to give (235), thus exemplifying the dual characteristics of 2,3-dihydropyrroles as imines and enamines. The ability of pyrrolines to react with nucleophiles is central to their biosynthetic role. For example, addition of acetoacetic acid (possibly as its coenzyme A ester) to pyrroline is a key step in the biosynthesis of the alkaloid hygrine (236). 

Ring closure resulting from attack of a heteroatom on a carboxyl group or its equivalent is merely a case of intramolecular esterification or amide formation. The y-butyrolactones or pyrrolidones obtained from such reactions are usually regarded as the province of aliphatic chemistry, so only a few examples are offered by way of illustration in Scheme 15. 

Most ring syntheses of this type are of modern origin. The cobalt or rhodium carbonyl catalyzed hydrocarboxylation of unsaturated alcohols, amines or amides provides access to tetrahydrofuranones, pyrrolidones or succinimides, although appreciable amounts of the corresponding six-membered heterocycle may also be formed (Scheme 55a) (73JOM(47)28l). Hydrocarboxylation of 4-pentyn-2-ol with nickel carbonyl yields 3-methylenetetrahy-drofuranone (Scheme 55b). Carbonylation of Schiff bases yields 2-arylphthalimidines (Scheme 55c). The hydroformylation of o-nitrostyrene, subsequent reduction of the nitro group and cyclization leads to the formation of skatole (Scheme 55d) (81CC82). 

Thermolysis of the aziridine (446) in the presence of diphenylketene gave a mixture of the pyrrolidone (447 minor product) and the oxazolidine (448 major product). In this instance the preferential addition to the C=0 bond is explained in terms of steric effects (72CC199). Similar addition to diphenylacetaldehyde takes place with the same orientation and the oxazolidine (448a) was obtained. When the reaction of the aziridine with the aldehyde was carried out in the presence of hydrogen selenide a selenazolidine was obtained (72BSB295). 

It is common for names of simple heterocyclic carbonyl derivatives to be contracted, with loss of the -ine ending of the parent name, e.g. pyridone, quinolone, acridone, pyrrolidone, thiazolidone. 

The 4-azidobutyrate ester is introduced via the acid chloride. Gleavage occurs by pyrrolidone formation after the azide is reduced by hydrogenation, H2S or Ph3P. ... 

The alcoholic filtrate contains appreciable amounts of pyrrolidone. The treatment with excess barium hydroxide converts this into the barium salt of the amino acid. ... 

The successful development of eye contact lenses led in turn to a demand for soft contact lenses. Such a demand was eventually met by the preparation of copolymers using a combination of an acrylic ester monomer such as methyl methacrylate, a cross-linkable monomer such as a dimethacrylate, and a monomer whose homopolymer is soluble or highly swollen in water such as N-vinyl pyrrolidone. Such copolymers swell in water (hence the term hydrophilic), the degree of swelling being controlled by the specific type and amount of the monomers used. In use the lens is swollen to equilibrium in water, a typical soft lens having a water content of about 75%. 

Poly(vinyl pyrrolidone) (PVP) was introduced by the Germans in World War II as a blood plasma substitute.A water-soluble polymer, its main value is due to its ability to form loose addition compounds with many substances. 

The monomer is prepared from acetylene, formaldehyde and ammonia via but-2-yne-1,4-diol, butane-1,4-diol, y-butyrolactone and y-pyrrolidone (Figure 17.8). 

In addition to its water solubility poly(vinyl pyrrolidone) is soluble in a very wide range of materials, including aliphatic halogenated hydrocarbons (methylene dichloride, chloroform), many monohydric and polyhdric alcohols (methanol, ethanol, ethylene glycol), some ketones (acetyl acetone) and lactones (a-butyrolactone), lower aliphatic acids (glacial acetic acid) and the nitro-paraffins. The polymer is also compatible with a wide range of other synthetic polymers, with gums and with plasticisers. 

Copolymers of vinyl pyrrolidone with vinyl acetate, styrene and ethyl aerylate have been marketed by the General Aniline and Film Corporation. See also section 18. 

Occasionally, water-soluble plastics are required. Poly(vinyl alcohol) is commonly the first to be considered but some cellulose ethers, polyethylene oxides, poly(vinyl pyrrolidone) and A-substituted polyamides are among many possible alternatives. 

---