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 Dimethylformamide" 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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=9067