2- benzyl alcohol buffer solution

Before releasing a process column for chromatography, it is advisable to perform some test to measure efficiency, such as calculating height equivalent theoretical plates (HETP), both to forestall any problems in the column bed and to provide a benchmark by which to measure column reproducibility and predict degradation of the bed or material. Examples of compounds that are relatively innocuous for use in pharmaceutical applications are 1% NaCl (for gel filtration), concentrated buffer solutions (for ion exchange), and benzyl alcohol and parabens for reverse phase LC.10... 

TABLE 9. Oxidation of X-substituted benzyl alcohols with Trametes villosa laccase and R2NO—H mediators in buffered (pH = 4.5) water solution at 25 °C. Comparison of p (vs. independently generated in MeCN solution at 25 °C... 

Besides local toxicity, discussed above, there are numerous other modes of potential adverse interactions involving excipients (19,20). Many of these pose little threat provided the amounts of excipients are constrained to certain levels. Excessive amounts, however, can cause problems, particularly for patients who are intolerant of even modest levels. Commonly used phosphate buffers may cause calcium loss with formation of insoluble calcium phosphates when such buffers are administered in over-ambitious amounts (21). Calcium phosphate precipitation has been noted particularly in nutritional parenteral admixtures for neonates because of the high nutrient requirements. Similarly, renal toxicity has been associated with depletion of zinc and other trace metals caused by large parenteral doses of ethylenediaminete-traacetic acid (EDTA) (22). Excessive absorption of glycine solutions, when used as irrigants during transurethral resections, can cause hyponatremia, hypertension, and confusion (23). The use of preservatives has been associated with cardiac effects in a few patients (24). Premature neonates were found to be at risk for receiving toxic amounts of benzoic acid or benzyl alcohol in bacteriostatic solutions used to flush intravenous catheters (25). 

Fig. 7. Time-resolved spectra and difference spectra for the pre-steady state and steady-state phases of the Co(II)E-catalyzed oxidation of benzyl alcohol by NAD at pH 9 (A, C) and pH 4.8 (B, D) and 25° for the wavelength range 300-450 nm. Scanning was carried out as described in the caption to Fig. 5. Difference spectra in (C) and (D) were calculated by subtracting the last spectrum collected in the pre-steady-state phase [respectively spectrum 8 of (A) and spectrum 10 of (B)] from all other spectra in the set. Single-wavelength time courses are shown in insets a and b of (A) and (B). Conditions after mixing were as follows (A, C) [Co(II)E], 29 fiN [NAD+], 1.4 mM [benzyl alcohol], 2 mM [IBA], 50 mAf 50 mM glycine and 50 mM Bis-Tris, final pH 9.0 (B, D) [Co(II)E], 29 fiN [NAD ], 3.5 mM [benzyl alcohol], 4 mM [IBA], 50 mM 10 mM H2SO4 and 50 mM Bis-Tris, final pH 4.8. Reaction was initiated by mixing enzyme in Bis-Tris buffer (pH 6.5) with NAD, benzyl alcohol, and IBA preincubated in the above-indicated solutions. (From Sartorius et al. with permission.) Copyright 1987 American Chemical Society.

Later in the same year, Uozumi, Yamada, and co-workers also reported an inwater dehydrative A(-alkylation reaction under air using a heterogeneous boron-iridium heterobimetallic Polymeric Catalyst 34 (Scheme 35) [184]. This method is suitable for the reactions of benzylic and aliphatic alcohols with ammonia, and primary, secondary, and cyclic amines. Different to usual hydrogen autotransfer reactions, which require basic conditions, the reactions of benzylic, aliphatic, and secondary amines and ammonia require a pH 4 aqueous buffer solution under microwave conditions. The catalyst can be recovered and reused at least twice without loss of activity. 

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