Phase diagram of (R)- and (S)-4-hydroxy-2-pyrrolidone mixtures: a new case of a conglomerate-forming system.
The phase diagram of (R)- and (S)-4-hydroxy-2-pyrrolidone presents a conglomerate in the racemic mixture. The enthalpy of melting extrapolated by the Schröder-van Laar-Le Chatelier equation [change in enthalpy (delta H) = 28410 J/mol; melting temperature (TA) = 429.9 K; solidus temperature (Ts) = 395.4 K] and the value determined by differential scanning calorimetry (delta H = 28494 J/mol; TA = 429.6 K; Ts = 394.6 K) are in excellent agreement. The experimental entropy of the mixing of enantiomers is 5.69 J/mol.K. The conglomerate nature of the racemic mixture was confirmed by X-ray and IR spectroscopy. The presence of solvates was also observed.
Di Silvestro
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G
Dipartimento di Chimica Organica e Industriale, Università di Milano, Italy.
Palmisano
G
G
Pellegata
R
R
D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D011760:Pyrrolidinones / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism; D013816:Thermodynamics; D014961:X-Ray Diffraction
D011760:Pyrrolidinones; C082967:4-hydroxy-2-pyrrolidone