Benzoates: analysis

Caf Na-benzoate Analysis in pharmaceuticals Nucleosi1 C18 not avai- MeOH-phosphate buffer 189... 

This aminium radical salt in aqueous solution in the form of solvated radical salt is very stable and will not polymerize acrylonitrile even with CeHsCOONa to form the corresponding benzoate. Therefore, we believe that in the nucleophilic displacement, there must be some intermediate step, such as intimate ion pair and cyclic transition state, which will then proceed the deprotonation to form the active aminium radical ion [14], as shown in Scheme 1. The presence of the above aminomethyl radical has also been verified [15] through ultraviolet (UV) analysis of this polymer formed such as PAN or PMMA with the characteristic band as the end group. 

Prepn. Dissolve 2.4g of Pb nitrate in 50ml w at 90—95°, and add with stirring a coned soln of Na benzoate (prepd by neutralizing 2g of benzoic acid with 0.6g NaOH). Evaporate the mixt on a w bath to a small vol while the liq still remains clear. Cool and add 50ml of 95% ethanol. This results in a very fine, light yel ppt, which is separated by vacuum filtration. After drying at 50°, analysis gave 41.82% Pb and 3.40% water... 

Figure 10 Capillary ion analysis of 30 anions 1 = thiosulfate, 2 = bromide, 3 = chloride, 4 = sulfate, 5 = nitrite, 6 = nitrate, 7 = molybdate, 8 = azide, 9 = tungstate, 10 = monofluorophosphate, 11 = chlorate, 12 = citrate, 13 = fluoride, 14 = formate, 15 = phosphate, 16 = phosphite, 17 = chlorite, 18 = galactarate, 19 = carbonate, 20 = acetate, 21 = ethanesulphonate, 22 = propionate, 23 = propanesulphonate, 24 = butyrate, 25 = butanesulphonate, 26 = valerate, 27 = benzoate, 28 = D-glutamate, 29 = pentane-sulphonate and 30 = D-gluconate. Experimental conditions fused silica capillary, 60 cm (Ld 52 cm) x 50 p i.d., voltage 30 kV, indirect UV detection at 254 nm, 5 mM chromate, 0.5 mM NICE-Pak OFM Anion-BT, adjusted to pH 8.0, with 100 mM NaOH. (From Jones, W. R. and Jandik, R, /. Chromatogr., 546, 445,1991. With permission.)...

The cooled reaction product is treated with 200 cc. of water, the layer of oil separated, washed once with a second portion of water, and subjected to distillation in vacuo. The first fraction of the distillate contains benzyl alcohol together with unchanged aldehyde, as well as a small quantity of water. The temperature then rises rapidly to the boiling-point of benzyl benzoate, when the receivers are changed. The product boils at 184-185°/15 mm., and analysis by saponification shows it to consist of 99 per cent ester. A yield of 410-420 g. is obtained, which corresponds to 90-93 per cent of the theoretical amount. This benzyl benzoate supercools readily, but after solidifying... 

X-ray analysis of 4,4-dimethylandrostan-3-on-17/3-yl benzoate (67) that the A ring is in a deformed chair conformation (225) in the crystal, and NMR and dipole moment measurements show the same to be true in solution. 

The stereochemistry of the acetate group at C(10) was confirmed by X-ray diffraction analysis of the corresponding benzoate. 

FIGURE 8 Analysis of the test mixture with (A) the SDS MEKC system containing 10 mM phosphate buffer (pH 7.5), 60 mM SDS, and 10% acetonitrile and (B) the CTAB MEKC system containing 25 mM phosphate buffer (pH 7.5), 10 mM CTAB, and 10% acetonitrile. Peaks I formamide 2 pyridine 3 aniline 4 meta-cresol 5 phenyl acetate 6 nitrobenzene 7 benzoic acid 8 thiamine 9 ethyl benzoate. (Reprinted from reference 270, with permission.)... 

Ion mobility spectrometry (IMS [43]). Solid phase microextraction (SPME) using a 100 pm polydimethylsiloxane (PDMS) SPME fibre was used for head-space sampling and preconcentration of volatile markers of cocaine, MDMA and marijuana (methyl benzoate, piperonal and terpenes, respectively) in cargo containers. Analysis was then performed by IMS after thermal desorption of the drug markers from the fibre into the IMS analyser. 

Kummert, R. Stumm,W. (1980) The surface complexation of organic acids on hydrous y-AI2O3. J. Colloid Interface Sd. 75 373—385 Rung, K.H. McBride, M.B. (1989) Adsorption of para-substituted benzoates on iron oxides. Soil Sd. Soc. Am. J. 53 1673-1678 Rung, K.H. McBride, M.B. (1989a) Coordination complexes of p-hydroxybenzoate on Ee-oxides. Clays Clay Min. 37 333-340 Kuntze, H. (1982) Iron clogging in soils and pipes. Analysis and treatment. DVWK Bull. 10. Parey, Hamburg, Berlin, 123 p. 

Yamada et al. reported the analysis of serum benzoate and hippurate in normal human and patients with chronic liver disease by using a HPLC method [40], The conditions for the analysis are given in Table 8. 

The structure of the benzoate derivative 166 was established by X-ray analysis, confirming the selective oxidation of the sulfur atom at the 6-position of thieno[2,3- ]thiophene-2-sulfonamides. The activated double bond of the cyclic vinyl sulfone moiety readily underwent nucleophilic addition, which was exemplified by reaction of 165 with 4-methoxybenzylthiol in the presence of base to provide a mixture of 167 and 168 <1999JHC249>. 

The most frequently used acyl derivatives, i.e., benzoates and cinnamates substituted in the 4-position, are listed in Table 7. The analysis of the stereochemistry of the bichromophoric system including a benzoate (cinnamate) chromophore is greatly simplified by its preference for s-trans conformation at the C(0)-0 bond, in which the carbonyl group is staggered ca. 30° to either side of the carbinyl C H bond. Consequently the direction of the electric dipole moment of the charge-transfer transition is approximately parallel to the C(H)-Q bond (Figure 16). 

Figure 2.5. Nucleophile selectivities determined from product analysis for the reactions of ring-suhstituted 1-phenylethyl derivatives (X-l-Y) with azide ion, acetate ion and methanol in 50 50 (v/v) water/trifluoroethanol. The selectivities are plotted against the appropriate Hammett substituent constant or a. Leaving group Y ( ) ring-suhstituted benzoates ( ) chloride (T) dimethyl sulfide (A) tosylate.

In the case of the concave acid 38a (s. Scheme 6), the Connolly routine showed that the m-phenylene chains were not sufficient to ensure a concave environment [33]. Unfortunately no crystals of the concave acids 38b and 38c (s. Scheme 6) with more extended chains X could be obtained which were suitable for an X-ray analysis. But NMR studies of the corresponding concave methyl benzoates 39 (s. Scheme 6) showed an increase in shielding by the chains X the larger the chains X were (39a - 39b -+ 39c) the more upfield the methyl signal of the ester groups in 39a-c was shifted in the NMR spectra [27b]. 

Fig. 5.2. Gas chromatography (GC) and electroantennography (EAG) analysis of male Manduca sexta antennal responses to floral volatiles from the night blooming cactus Peniocereus greggii. The upper trace is a flame ionization detection (FID) chromatogram of floral headspace odors separated on a carbowax GC column, while the lower trace is a simultaneous recording of summed antennal action potentials elicited by individual compounds as they elute. The largest absolute responses followed methyl benzoate, methyl salicylate, and benzyl alcohol (peaks 3-5, respectively). Note the poor responses (circled) to benzaldehyde and benzyl benzoate (peaks 2, 6) and the disproportionately higher responses (bold arrows) to methyl salicylate and benzyl salicylate (peak 7) relative to their peak areas. Peak 1 is the internal standard (toluene) remaining unnumbered peaks are ambient contaminants.

Since it was deemed desirable to remove possible interaction between the benzoate and the furan chromophores for the unambiguous CD analysis, salvinorin A (1) was reduced under cataytic hydrogenation conditions, providing the hexahydro derivative 4 (a 2 1 epimeric mixture at C-13) after... 

---