X-Message-Number: 9067
Date: Thu, 29 Jan 1998 13:11:42 -0800 (PST)
From: Doug Skrecky <>
Subject: diethylformamide and dimethylformamide

 Boutron P, and Baudot A.
 "Calorimetric Study of Aqueous Solutions of Diethylformamide and
 Cryobiology 35(4): 329-330 December 1997

   Aqueous solutions of diethylformamide (DEF) and dimethylformamide (DMF)
 have been studied by differential scanning calorimetry on cooling and
 warming betweeen -153 and 0 C. With DEF, no hydrate forms except during
 warming at 2.5 C/min after quenching. On warming, only the glass
 transition, the ice formation, amd melting are observed. With DMF, the
 thermograms are much more complicated, with hydrate formation. The last
 hydrate melts at -48 C. The wholly amorphous state could not be obtained
 with 35% (w/w) of any of these solutes. The critical cooling rate Vccr to
 avoid any crystallization is repectively 300, 75, and 20 C/min for 40,
 45, and 50% (w/w) DEF. The critical warming rate Vwcr to avoid any
 crystallization from a wholly amorphous solution is respectively
 10,000,000, 900, and 110 C/min for 40, 45, and 50% (w/w) DEF. For DMF,

 Vccr and Vwcr are respectively Vccr = 500, 35, and 7 C/min, and Vwcr  
 10,000,000,000 (from an almost wholly amorphous solution), 295, and 150
 C/min for 40, 45, and 50% of this compound. Therefore, the glass-forming
 tendency on cooling these two compounds is greater than glycerol and
 ethylene glycol, but less than 1,2-propanediol and levo-2,3-butanediol
 (Boutron P, Cryobiology 30: 86-97 1993). The stability of the wholly
 amorphous state on warming these compounda is also greater than glycerol
 and ethylene glycol and less than 1,2-propanediol and
 levo-2,3-butanediol. These amides are, on warming, more efficient than
 DMSO at the concentration of 50% (Boutron P, Cryobiology 30: 86-97 1993).
 According to the manufacturers, DEF is less toxic than DMF. These
 compounds could be good cryoprotectants if they are not too toxic, and if
 one can avoid damage due to the hydrate of DMF.

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