Room-temperature liquid

Cong P, Deuhl H P and Simon J D 1993 Using optical coherence to measure the ultrafast electronic dephasIng of large molecules In room-temperature liquids Chem. Phys. Lett. 211 367-73... 

In the cycle shown, gaseous oxygen and nitrogen are withdrawn at room temperature. Liquid oxygen could be withdrawn from point A and liquid nitrogen from point E, but in this case more refrigeration would oe needed. 

Three classes of anhydride may be recognised, room temperature solids, room temperature liquids and chlorinated anhydrides. 

Reduction in cation symmetry (ideally to Cl) lowers the freezing point and markedly expands the range of room-temperature liquid salts. Table 3.1-4 shows the effect of symmetry for a series of [NR4]X salts, in which all the cations contain 20 carbon atoms in the allcyl substituents [44]. 

The final coal product in the MeOH/KOH experiments was 20%-25% soluble in the methanol. When the methanol was removed, the resultant product was a room temperature liquid with the properties described in Table V. Apparently the polymethylphenol fraction is formed by the cleavage of phenolic ethers and subsequent methyla-tion by the CO that is present in the reaction mixture as a result of methanol decomposition. The methylation reaction has been observed before for similar systems (3). 

Although thermally rather unstable at room temperature, liquid diboron tetrachloride decomposes relatively slowly at temperatures below 0°. In the gas phase, the substance may be exposed to ambient temperatures for periods as long as 5 to 10 minutes without the risk of appreciable deterioration. The colorless substance melts5 at —93.0° and its vapor pressures in the interval —63.5 to 22.5° are given by the equation 3... 

In 1992, the ionic liquid methodology received a substantial boost when Wilkes and Zaworotko described the synthesis of non-chloroaluminate, room temperature liquid melts (e. g. low melting tetrafluoroborate melts) which may be regarded as second generation ionic liquids [6]. Nowadays, tetrafluoroborate and (the slightly later published [7]) hexafluorophosphate ionic liquids are still widely used in ionic liquid research. However, their use in many technical applications will be clearly limited by their relatively high sensitivity towards hydrolysis. Of course, the tendency of their anions to hydrolyse is much less pronounced than for the chloroaluminate melts but it still clearly exists. Consequently, the technical application of tetrafluoroborate and hexafluorophosphate ionic liquids will be effectively restricted to those applications where water-free conditions can be realised at acceptable costs. 

Figure 2.1 Compounds that form room-temperature liquid crystals...

Figure 5 (a) Typical end-of-pulse absorption spectra obtained in pulse radiolysis of room temperature liquid acetonitrile (7-nsec fwhm pulse of 20 MeV electrons). The 500-nm peak is from anion-2 (dimer radical anion) the 1450-nm peak is from anion-1 (cavity electron), (b) Energy diagram and sketches of anion-1 and anion-2 (see the text). 

While anion-2 is clearly the dimer radical anion of acetonitrile, identification of anion-1 as a cavity electron requires caution. First, we stress that anion-1 cannot be the monomer anion of acetonitrile. The monomer anion does not absorb in the NIR [30,46,52]. For the monomer anion to occur at all, the neighboring acetonitrile molecules should all be oriented in the same direction, as in p-acetonitrile otherwise, coupling to a neighboring (antiparallel) molecule reduces the overall energy and causes instant dimer formation. It is difficult to see how such a fortuitous orientation could persist for 0.3-3 nsec in a room temperature liquid. Also, it is not clear why a monomer anion would... 

Alkyl sulfates are conjugate bases of the very strongly acidic alkyl sulfuric acids and are very good leaving groups. Dimethyl sulfate is less expensive than CH,I, the only liquid methyl halide at room temperature. Liquids are easier to use than gases in laboratory syntheses. 

If the adsorption isotherm is to be determined at some temperature other than room temperature-liquid nitrogen temperature, for example—the sample tube is placed in a suitable thermostat. This is indicated by the dotted line in Figure 9.3. In this case two sets of readings are made with the nonadsorbed gas, one at room temperature and one with the thermostat in place. In this way the partitioning of the dead space between the two temperature regions can be determined. Several additional considerations should be cited that are important in actual practice ... 

Figure 42 ESR spectra of copper(II)-doped [Zn(phen)2(02CMe)](BF4)-2H20394 (a) poiycrystalline sample, and (b) single-crystal sample (--------------) room temperature (---) liquid nitrogen temperature914...

The molecular length should be at least 1.3 nm (13 A), consistent with the presence of long alkyl groups on many room-temperature liquid crystals. 

De La Campa MRF, Garcia MED, Sanz-Medel A. 1988. Room-temperature liquid phosphorimetry of the aluminum-ferron chelate in micellar media-determination of aluminum. Anal Chim Acta 212 235-243. 

Name 2-Ethylhexyl carbonate coated or bonded on cholesteryl silica (room temperature liquid crystal) Structure ... 

Figure 3.20 Longitudinal dielectric relaxation in room-temperature liquid acetonitrile. Depicted is a comparison between the longitudinal dipole (dashed line) and charge density...

The electronic absorption spectra of complex molecules at elevated temperatures in condensed matter are generally very broad and virtually featureless. In contrast, vibrational spectra of complex molecules, even in room-temperature liquids, can display sharp, well-defined peaks, many of which can be assigned to specific vibrational modes. The inverse of the line width sets a time scale for the dynamics associated with a transition. The relatively narrow line widths associated with many vibrational transitions make it possible to use pulse durations with correspondingly narrow bandwidths to extract information. For a vibration with sufficiently large anharmonicity or a sufficiently narrow absorption line, the system behaves as a two-level transition coupled to its environment. In this respect, time domain vibrational spectroscopy of internal molecular modes is more akin to NMR than to electronic spectroscopy. The potential has already been demonstrated, as described in some of the chapters in this book, to perform pulse sequences that are, in many respects, analogous to those used in NMR. Commercial equipment is available that can produce the necessary infrared (IR) pulses for such experiments, and the equipment is rapidly becoming less expensive, more compact, and more reliable. It is possible, even likely, that coherent IR pulse-sequence vibrational spectrometers will... 

Photolysis of a CO ligand from the parent compound initiates the reaction. The resultant >j3-Tp Rh(CO) complex has a coordinatively vacant site that is quickly occupied by a solvent molecule. The time scale for such a solvation process is generally on the order of 2 ps in room temperature liquids (28). The solvated 3-Tp Rh(CO)(S) (S = alkane) complex exhibits a single CO-stretching band (vCo) at 1972 cm 1 (the v = 0 1 band) as shown in Fig. 4a. For this particular system the large... 

More importantly, the use of heavy metal anionic micellar media has been shown to allow for observation of analytically useful room-temperature liquid phosphorescence (RTLP) (7.484.487). There are several examples in which phosphorescence has been employed as a LC detector with the required micellar assembly being present as part of the LC mobile phase (482) or added post column (485). More recently, metal ions have been determined in a coacervate scum by utilizing the micellar-stabilized RTLP approach (498). Thus, the future should see further development in RTLP detection of metal ions in separation science applications. 

---