Trifluoroacetic acid, physical properties

Physical Properties. Trifluoroacetic acid [76-05-1], CF COOH, is a colorless Hquid with a sharp odor resembling that of acetic acid. Its... 

Manganese is roughly similar to Fe in its physical and chemical properties, the chief difference being that it is harder and more brittle but less refractory (mp 1247°C). It is quite electropositive and readily dissolves in dilute, non-oxidizing acids, e.g., trifluoroacetic acid gives Mn(CF3C02)2.1... 

The physical properties of liquid trifluoroacetic acid are given in Table I. At normal temperatures it is a colorless liquid which fumes readily in moist air and has a powerful odor. 

Several physical properties of amorphous poly-DSP films have been measured64). For the preparation of amorphous films, a trifluoroacetic acid solution containing 10% poly-DSP is cast on a glass plate and dried in vacuo. The resulting film is extracted with triethylamine to remove the last traces of the acid and then extracted with ethanol. 

Many cellulose derivatives form lyotropic liquid crystals in suitable solvents and several thermotropic cellulose derivatives have been reported (1-3) Cellulosic liquid crystalline systems reported prior to early 1982 have been tabulated (1). Since then, some new substituted cellulosic derivatives which form thermotropic cholesteric phases have been prepared (4), and much effort has been devoted to investigating the previously-reported systems. Anisotropic solutions of cellulose acetate and triacetate in tri-fluoroacetic acid have attracted the attention of several groups. Chiroptical properties (5,6), refractive index (7), phase boundaries (8), nuclear magnetic resonance spectra (9,10) and differential scanning calorimetry (11,12) have been reported for this system. However, trifluoroacetic acid causes degradation of cellulosic polymers this calls into question some of the physical measurements on these mesophases, because time is required for the mesophase solutions to achieve their equilibrium order. Mixtures of trifluoroacetic acid with chlorinated solvents have been employed to minimize this problem (13), and anisotropic solutions of cellulose acetate and triacetate in other solvents have been examined (14,15). The mesophase formed by (hydroxypropyl)cellulose (HPC) in water (16) is stable and easy to handle, and has thus attracted further attention (10,11,17-19), as has the thermotropic mesophase of HPC (20). Detailed studies of mesophase formation and chain rigidity for HPC in dimethyl acetamide (21) and for the benzoic acid ester of HPC in acetone and benzene (22) have been published. Anisotropic solutions of methylol cellulose in dimethyl sulfoxide (23) and of cellulose in dimethyl acetamide/ LiCl (24) were reported. Cellulose tricarbanilate in methyl ethyl ketone forms a liquid crystalline solution (25) with optical properties which are quite distinct from those of previously reported cholesteric cellulosic mesophases (26). 

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