Acetonitrile solubility parameter

A gradient that runs with 30-80% methanol or acetonitrile is not uncommon. This amount of modifier is generally not needed in supercritical fluid chromatography to affect the same separation. Typical modifier composition in SFC is 1.0-10% and would achieve higher Hildebrand Solubility Parameter adjustment overall than the broader gradients found in LC. 

Table V lists the common solvents used for cleaning XAD resins and their respective solubility parameters. Methanol and acetonitrile [which are used in the cleanup procedure of Junk et. al. (5)] have very different total solubility parameters than the compounds listed in Table IV. Thus, they should be less efficient for eluting the resin contaminants from the resin polymers. This situation explains the GC profile results, which show large numbers and high concentrations of contaminants after the successive 24-h Soxhlet extractions using methanol, acetonitrile, and ethyl ether (Figure 2).

Hence, a mixture of 50% methanol in water is expected to yield roughly the same capacity factors as a mixture of 31% THF in water. Similarly, for acetonitrile with a solubility parameter of 13.14, we find that... 

These very simple relationships can be verified experimentally as is shown in figure 3.16. The iso-eluotropic compositions of binary mixtures of THF and acetonitrile with water have been plotted against the binary methanol-water composition. The thin straight lines indicate the theoretical relationships from solubility parameter theory (eqns. 3.50 and 3.51). The thick lines correspond to average experimental data over large numbers of solutes [335]. An (average) experimental data point can be found as follows. 

Figure 3.16 Iso-eluotropic compositions for binary mixtures of THF and acetonitrile in water, relative to methanol/water mixtures. The solid lines represent the average experimental compositions for a large number of solutes. The thin lines represent calculated compositions from solubility parameter theory (eqns.3.50 and 3.51). Figure taken from ref. [311]. Reprinted with permission.

The relative polarity of solvents in the polarity index scheme differs from that in the solubility parameter scheme. For example, using 8 values methanol is more polar than acetonitrile whereas using Snyder s polarity index, acetonitrile is more polar than methanol. Practical experience suggests that methanol is more polar than acetonitrile and therefore supports the solubility parameter approach. 

The polarity index or the solubility parameter may be used as a measure of solvent strength, which would be a measure of polarity in those cases. For reversed phase HPLC, solvent strength parameters have been proposed for the four most common solvents used, i.e. water (Si = 0), methanol (Si = 2.6), acetonitrile (Si = 3.2) and THF (Si = 4.5). Using these values water makes no contribution to the eluting power of the mobile phase and the solvent strength is measured by the volume fraction of organic modifier. 

Very little data on the Hildebrand solubility parameters of ionic liquid-solute systems is available to date. A study of eight ionic liquids using viscosity measurements in different solvents indicated polarities similar to allyl alcohol or dimethylsulfoxide [35], More recent work has shown that the solubility parameters can be reliably estimated from surface tension and density measurements [36], The equilibrium position of keto-enol tautomers in conjunction with quantitative H-NMR-, IR- and UV/Vis-spectroscopy has been studied in ionic liquids [37, 38], where the stabilisation of the enol form is favoured in non-polar solvents in general. Comparison to the relative tautomer ratios obtained in methanol and acetonitrile indicated that even hydrophobic (non-polar) [BTA]-based ionic liquids were more polar than these organic solvents. 

Achieving a suitable particle size with better yield is important in precipitation polymerization as many parameters affect its mechanism. We have prepared GA based MIPs by the precipitation polymerization and observed the effect of porogen on particle size and specific molecular recognition properties (Pardeshi et al, 2014], MIP, M-lOO prepared in the porogen acetonitrile and MIP, M-75 prepared in a mixture of acetonitrile-toluene (75 25 v/v), resulted in the formation of microspheres with approximately 4 pm particle size and surface area of 96.73 m g and nanoparticles (0.8-1000 nm] and a surface area of 345.9 m g" respectively. The results have shown that effect of toluene on the particle size of MIPs depends on the type of cross-linker used and its solubility parameter. Matching the solubility parameter of solvent mixture and cross-linkers is important to obtain the desired particle size in MIPs. The MIPs selectively recognized GA in presence of its structural analogues. Pure GA with percent recovery of 75 ( 1.6) and 83.4 ( 2.2) was obtained from the aqueous extract of herb Emblica officinalis by M-lOO and M-75, respectively. 

In RPLC, by considering eqn [5] and the values from Table 1, to a first approximation, it may be expected that mixtures of the same solubility parameter will yield the same solute retention factor. In other words, if acetonitrile (ACN) or tetrahydrofu-ran (THF) is used instead of methanol (MeOH) in a binary mixture with water, a composition of 9 ACN = 0 78 MeOH < THF = 0-fi2 MeOH is expected to yield roughly the same retention factor as the composition... 

PECA is soluble in several highly polar solvents including nitromethane, DMF, acetone, tetrahydrofuran, and acetonitrile. Donnelly and Pepper have presented a more complete list of solvents and non solvents for polymethyl, polyethyl, and poly-n-butyl cyanoacrylate. These authors calculated the solubility parameter of PECA to be 11.2. Water absorption by PECA at room temperature and 50% RH is negligible.""... 

Table 10.8 lists the solvent-resin radius of interaction values ( / ) of five resins with each of five amides, acetonitrile, and two morpholine derivatives. These values are a measure of the solubility of the resin in the solvent. As described in Chapter 5 the total solubility parameter of a resin is the point in three-dimensional space where the three partial solubility parameter vectors meet as the center point of the idealized spherical solubility envelope. The distance in space between two sets of solvent-resin parameters can be represented by the term radius of interaction, The Lotus spreadsheet, SPWORKS.WKl, which lists some 166 resins and polymers and 289 solvents, was used to calculate the R values given in Table 10.8. Small R values (e.g., less than 10) would signify good solvency for the resin while higher values would suggest a poor solvent for the resin. If the actual radius of the resin solubility envelope is known then the / value should be less than the resin radius if the solvent is to dissolve the resin.

Figure 10.1 Hansen solubility parameters of four amide-type solvents, two morpholine derivatives, and acetonitrile in terms of the polarity and hydrogen bonding values. The average values of the alcohol-type solvents, ester-type solvents, ether solvents, ketone solvents, and the average values for the E-series glycol ethers are included also.

Any of the common laboratory solvents can be used in the extractor, but the final choice will depend on the analytes that are to be extracted. Fritzpatrick and Dean described a method for selecting the optimum solvent for the extraction of DDT (and metabolites) and pentachlorophenol (PCP) from soil when using ASE they broke the Hildebrand solubility parameter down into three components, to optimally select methylene chloride for DDT and a mixmre of methylene chloride and acetonitrile for PCP (61). 

Cr CNNi(tetren) 6](C104)9 is a red-purple solid, soluble in water-acetonitrile mixtures where the undissociated heptanuclear entity can be identified by electrospray ionization mass spectrometry. IR spectroscopy shows the presence of a unique /cn band at 2146 cm of the bridging cyano ligand and an intense band of the perchlorate anion at cr = 1090 cm The IR spectrum of the C-enriched compound prepared from K3[Cr( CN)6] displays a /cn band at 2103 cm The compound crystallizes in a trigonal system, space group R3, with parameters a = b = 15.274 A and c = 41.549 A. The magnetic properties indicate a ferro-... 

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