Partial Molar Volumes and Partial Molar Isentropic Compressions of Four 2-Alkoxyethanols at Infinite Dilution in Water at Temperatures T = 278–343 K and Atmospheric Pressure

Abstract

Density and speed of sound data for dilute aqueous solutions of four linear 2-alkoxyethanols, H–(CH2) n –O–CH2–CH2–OH, C n E1 for n = 1, 2, 3, 4, were measured using the Anton Paar DSA 5000 vibrating-tube densimeter and sound analyzer in the temperature range from 278.15 to 343.15 K and at atmospheric pressure. Standard molar volumes and standard molar isentropic compressions were evaluated from the measured data. Present data were compared with values available for selected linear aliphatic polyethers and poly­(ethylene glycols) and structure–property relationships were analyzed. Apparent molar quantities of aqueous 2-butoxyethanol in wider concentration range were evaluated and effects of aggregation of the solute molecules were considered.

Partial Molar Volumes and Partial Molar Isentropic Compressions of Two Poly(ethylene glycol) Monoalkyl Ethers, C4E2 and C1E3, at Infinite Dilution in Water at Temperatures T = 278–343 K and Atmospheric Pressure

“…Compressions of the two investigated solutes, the molecules of which are of nearly same shape and size, obey correctly this general rule (the slope of C 1 E 3 is smaller than that of C 4 E 2 ). All dependences cross each other at temperatures around 300 K, which is in accordance with previous observations. ,, …”

“…The values increase with increasing temperature being negative at low temperatures. Obviously, the slopes (∂ K S , m,2 0 /∂ T ) p approximately follow the trend observed in the homologous series of glymes and 2-alkoxyethanols, i.e., it decreases with the increasing hydrophilic character of the solute. Compressions of the two investigated solutes, the molecules of which are of nearly same shape and size, obey correctly this general rule (the slope of C 1 E 3 is smaller than that of C 4 E 2 ).…”

“…Plots of standard molar isentropic compression K S , m,2 0 against temperature T . open circle - ethylene glycol monomethyl ether (2-methoxyethanol, C 1 E 1 ), solid circle - triethylene glycol monomethyl ether (C 1 E 3 ) (this work), open square ethylene glycol monobutyl ether (2- butoxyethanol, C 4 E 1 ), solid square - diethylene glycol monobutyl ether (C 4 E 2 ) (this work), and triangle - triethylene glycol (C 0 E 3 ) …”

“…Experimental standard molar isentropic compressions of the solutes studied here are plotted against temperature in Figure along with the values for the solutes selected for a comparison in Figure above (C 1 E 1, C 4 E 1, and C 0 E 3 ). The values increase with increasing temperature being negative at low temperatures.…”

“…The present paper is a part of the investigation of aqueous solutions of aliphatic linear polyethers and ether alcohols containing one or more molecular segments of −O–CH 2 –CH 2 –, i.e., the solutes with a general formula of G 1 –(O–CH 2 –CH 2 ) m –O–G 2 : (i) poly­(ethylene glycols) − (G 1 G 2 H), (ii) poly­(ethylene glycol) dimethyl ethers − (glymes, G 1 G 2 CH 3 ), and (iii) poly­(ethylene glycol) monoalkyl ethers ,− (G 1 H–(CH 2 ) n , G 2 H), often denoted as C n E m . This study is an extension of recently published results of density measurements performed for dilute aqueous solutions of two poly­(ethylene glycol) monoalkyl ethers: diethylene glycol monobutyl ether H–(CH 2 ) 4 –(O–CH 2 –CH 2 ) 2 –OH (C 4 E 2 ) and triethylene glycol monomethyl ether, H–(CH 2 )–(O–CH 2 –CH 2 ) 3 –OH (C 1 E 3 ) in the temperature range from 298 to 573 K and pressures up to 30 MPa.…”