Acetonitrile specific conductance

Acetonitrile has been distd from AgN03, collecting the middle fraction over freshly activated AI2O3. After standing for two days, the liquid was distd from the activated AI2O3. Specific conductivity 0.8-1.0 x 10 mhos [Harkness and Daggett Can J Chem 43 1215 1965]. Acetonitrile C was purified by gas chromatography and is water free and distd at 81°. [7 Mol Biol SI 541 1974.]... 

Electrical Conductivity. A further topic which needs to be considered is the correlation found by Zlamal, Ambroz, and Vesely [2] between the specific conductivity of solutions (mainly in ethyl chloride) of aluminium chloride containing various quantities of a polar compound (acetonitrile, butyraldehyde, ethanol, etc.) and the DP of the polyisobutenes formed in these solutions. Over a certain range of concentrations there is an inverse correlation between the specific conductivity, which has a sharp minimum when the ratio [AlCl3]/[Additive] = 1, and the DP, which at the same composition shows a sharp maximum. 

Lithium perchlorate was purified as described earlier (6). Acetonitrile was Fisher ACS reagent grade and was used without further purification. Water was distilled twice, the second time in a Corning AG-2 all glass still, and had a specific conductivity at 25°C of 8 X 10 7 ohm-1 cm-1. The mixed solvents were prepared by weight as shortly as possible before heat measurements were made. 

The conductance method is satisfactory only if the solvent can be rigorously purified. Through failure to appreciate this, the first values of pKa of picric acid in acetonitrile proved to be much too small, 5.6 and 8.9 as compared with 11.0 from electromotive force measurements on buffered solutions. D Aprano and Fuoss found that acetonitrile having a satisfactory specific conductance of about 10 cm still contained a trace of ammonia. This was converted to ammonium pic-rate when acid was added to the solvent giving a spurious contribution to the conductance of picric acid solutions. This discovery moved them to make the flat assertion that dissociation constants of weak acids cannot be determined in aprotic solvents conductimetrically . This may be an overly pessimistic view, conductance values of pKa for acids in di-methylsulphoxide and dimethylformamide agree well with those from spectrophotometric and electromotive force measurements. Approximate values of pKa and pKf can be obtained from conductometric titrations of a weak acid with a weak base. ... 

FIGURE 9 Specific conductivity k versus molarity m at 25°C for BU4NCIO4 in mixed solvents propylene carbonate-acetonitrile (mole fraction of acetonitrile is indicated on the right side of each curve). Points measured data full lines Eq (79) dashed lines MSA equation. 

The white solid pyridine adduct was stable in vacuo at room temperature, and dissolved in excess pyridine or in acetonitrile to give moderately stable solutions. The specific conductivity of these solutions has been compared with that of tetrapropylammonium iodide in the same solvents and it is clear that the adduct is considerably dissociated as [SiH pyJ ". In air, the adduct fumed and was partly oxidised to iodine, while it reacted slowly with water to yield ... 

Within the class of organic electrolyte the discussion is focused today on the use or not of acetonitrile (AN, http //en.wikipedia.org/wiki/Acetonitrile). This solvent provides 10 times more ionic conductivity than propylene carbonate (PC) in the low-temperature range of the specification [37], In 2004, AN has been declassified in the EU from toxic to harmful. The change is currently under inspection in the State. IS014000 environmental standard do not prohibit any product as it is sometime mentioned. It requires a control and an improvement of the environmental and security situation. 

A conductometric device for measurement of benzyltriphenylphosphonium ions was developed next [80]. Particles of benzyltriphenylphosphonium chloride-imprinted MAA-EDMA copolymer were held in a layer between two platinum wires using a filter paper. The device was exposed to the analyte in acetonitrile, an AC potential applied and the conductance recorded. The direct measurement principle is based on the enrichment of the analyte, a charged species, close to the electrode. A semi-linear response was observed between 1 mg/1 and 20 mg/1 (Fig. 18.4). In the two latter sensors it was anticipated that the effect of non-specific... 

Heck reactions are conducted in polar aprotic, cr-donor-type solvents such as acetonitrile, dimethyl sulfoxide, or dimethylacetamide. Reaction temperatures and times largely depend on the nature of the organic halide to be activated and on the catalyst s stability limit. lodo derivatives are much more reactive (<100 °C), so auxiliary (phosphine) ligands are not necessary here. Polar solvents such as DMF, DMAc, and A-methylpyrrolidone (NMP) in combination with NaOAc as base are specifically beneficial in all cases, and even mild phase-transfer conditions in a solid/solution system employing Pd(OAc)2 without phosphine co-ligands), [N(n-C4H9)4]X in DMF (X = Cl, Br), and K2CO3 as base ( Jeffery conditions ) [17, 18]. 

The electropolymerization of these monomers at constant current under the same micellar conditions led to the formation of thin, electroactive polymer films. The electropolymerization of 0.05 M EDOT in 0.1 M SDS containing O.IM LiC104 in water at a Pt electrode began at very low current (j = 0.1 mA/cm ), compared to that found in acetonitrile without SDS (j = 0.5 mA/cm ). This phenomenon nuy be attributed to a specific effect of the SDS surfactant, which alters the oxidation potentials of EDOT. Thin, electroactive and conductive poly(EDOT) films can be synthesized in the above aqueous micellar solution at constant currents ranging firom j = 0.1 mA/cm to j = 5 mA/cm. For j > 5 mA/cm the resulting poly(EDOT) films were non-electroactive and extremely degraded owing to the reaction between water molecules and the thienyl radical-cations formed (8). 

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