Chloride transfer

Weighing as calcium oxide. Decant the clear supernatant liquid through a Whatman No. 40 or 540 filter paper, transfer the precipitate to the filter, and wash with a cold 0.1-0.2 per cent ammonium oxalate solution until free from chloride. Transfer the moist precipitate to a previously ignited and weighed... 

Subsequently, elute the target substance with 50 mL of the same buffer solution containing 0.1 M sodium chloride. Transfer this eluate to a 200-mL separatory funnel,... 

Recovery of acetamiprid, IM-1-2 and IM-1-4. Combine 20 g of the air-dried soil with 100 mL of a mixed solvent of methanol and 0.1 M ammonium chloride (4 1, v/v) in a 250-mL stainless-steel centrifuge tube, shake the mixture with a mechanical shaker for 30 min and centrifuge at 8000 r.p.m. for 2 min. Filter the supernatant through a Celite layer (1-cm thick) under reduced pressure into a 500-mL flask. Add a second 100 mL of mixed solvent to the residue and then extract and filter in the same manner. Combine the filtrates and add 150mL of distilled water with 1 g of sodium chloride. Transfer the aqueous methanol solution into a 1-L separatory funnel and shake the solution with 200 mL of dichloromethane for 5 min. Collect the dichloromethane in a flask and adjust the pH of aqueous methanol to 13 with sodium hydroxide. Extract the solution with two portions of 200 mL of dichloromethane for 5 min. Combine the dichloromethane extracts and pass through a filter paper with anhydrous sodium sulfate. Add 0.5 mL of diethylene glycol and then concentrate the dichloromethane extract to about 0.5 mL on a water-bath at ca 40 °C by rotary evaporation. 

The addition of HC1 to 1,3-butadiene in the gas phase at total pressures lower than 1 atmosphere and at temperatures in the range of 294-334 K yielded mixtures of 3-chloro-l-butene and ( )- and (Z)-l-chloro-2-butenes, in a ratio close to unity44,45. Surface catalysis has been shown to be involved in the product formation (Figure 1). The reaction has been found to occur at the walls of the reaction vessel with a high order in HC1 and an order less than unity in diene. The wall-catalyzed process has been described by a multilayer adsorption of HC1, followed by addition of butadiene in this HC1 layer. This highly structured process is likely to involve near simultaneous proton and chloride transfers. 

I.M. Doughty, J.D. Glazier, S.L. Greenwood, R.D. Boyd, and C.P. Sibley. Mechanisms of matemofetal chloride transfer across the human placenta perfused in vitro. Am I Physiol. 27LR1701-R1706 (1996). 

Stephenson has developed a convenient procedure for preparing J-chloro-3-phenoxy-2-propanols from epichlorohydrin nnd phenols, which is economical of reagents and minimizes the formation of undesirable side-products (Eq. 600). He has also greatly extended the applicability of hydrogen chloride transfer for the preparation of epoxides. ... 

Aqueous samples subjected to purge and trap extraction sample aliquot purged under helium flow highly volatile methyl chloride transferred from aqueous matrix to vapor phase absorbed on a sorbent trap analyte thermally desorbed and swept onto a GC column for separation detected by HECD, ECD, FID or MSD low retention time. 

The procedure is the same as outlined above except that 1.0 g. of potassium chloride is added to the 150 g. of tin before reduction. Moreover, if the solution of tungsten-(YI) chlorides is allowed to stand overnight, the filtration step can be omitted in this case and the supernatant liquor poured directly on the tin-potassium chloride. Transfer of solid material should be avoided, but a very small amount of potassium chloride in addition to that added will not be harmful as the 1-g. amount is an excess. Since K5W3CI14 is more soluble than K3W2CI9, the yield is somewhat lower, about 45 to 50%. 

Halide abstraction reactions are very common and usually fast processes. These reactions have also proved extremely useful for two specific applications in the field of physical organic chemistry. First, for obtaining thermochemical stability data of carboca-tions through the measurement of gas-phase chloride transfer equilibria (equation 1). 

Sodium Chloride Transfer about 5 g of sample, accurately weighed, into a 250-mL beaker, add 50 mL of water and 5 mL of 30% hydrogen peroxide, and heat on a steam bath for 20 min, stirring occasionally to ensure complete dissolution. 

When comparisons are possible, a AAG(ci) ladder for the chloride-transfer equilibria (29) of benzylic halides can be superimposed upon the corresponding AAG(cc)h ladder for proton transfer (26). Thus a wide set of relative gas-phase stabilities of carbocations can be built up based on the same scale. 

The series of a-CFs-benzyl cations [40C ] derived from the chloride-transfer equilibrium (29) gives an excellent linear correlation for the full range of substituents down to 3,5-F2 (Fig. 28) (Mishima et al., 1990a, 1997). 

Chloride transfer equilibria of triarylmethyl- [34] and diarylmethyl cations [35] have been determined by H NMR spectroscopy they have been combined to give a chloride affinity scale (Scheme 5). 

Scheme 5 H NMR spectroscopic determination of chloride transfer equilibria (-70° C, CD2C12). (From Ref. 35.)...

Let us first ignore ion-pairing phenomena. With this assumption, the chloride transfer equilibria (13) correspond to the chloride transfer equilibria between two carbocations which were described in Scheme 5 and thus provide a comparison of the chloride affinities of metal halides and of carbocations. One would expect the right side of this equilibrium to be favored if MCI, is the stronger Lewis acid and the left side when R+ is the stronger Lewis acid. 

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