Derivatization iodide

Note The reagent can be employed on silica gel and cellulose layers. When derivatization is carried out from the vapor phase the detection limit for morphine is 10 ng and that for papaverine 1 ng per chromatogram zone [5]. In some cases it has been recommended that ammonium sulfate be added to the layer with subsequent heating to 150 —180 °C [1] after derivatization. It is also possible to spray afterwards with an aqueous solution of potassium iodide (1 %) and starch (1%) [2]. 

Bocarsly AB, Walton EG, Wrighton MS (1980) Use of chemically derivatized n-type sU-icon photoelectrodes in aqueous media. Photooxidation of iodide, hexacyanoiron(II), and hexaammineruthenium(II) at ferrocene-derivatized photoanodes. J Am Chem Soc 102 ... 

Transfer the residue with 2 x 1 mL of DMSO into a 10-mL centrifuge vial. Add 20 iL of methyl iodide and 200 pL of 1M sodium hydroxide solution, mix and plug the vial with a stopper. Derivatization is done at 70 °C for 1 h. After addition of 45 mL of aqueous 10% sodium chloride, extract the reaction mixture with 10 or 2 x 10 mL of n-hexane. Transfer the n-hexane phase on to the chromatographic column prepared as described below. 

Cyanide and thiocyanate anions in aqueous solution can be determined as cyanogen bromide after reaction with bromine [686]. The thiocyanate anion can be quantitatively determined in the presence of cyanide by adding an excess of formaldehyde solution to the sample, which converts the cyanide ion to the unreactive cyanohydrin. The detection limits for the cyanide and thiocyanate anions were less than 0.01 ppm with an electron-capture detector. Iodine in acid solution reacts with acetone to form monoiodoacetone, which can be detected at high sensitivity with an electron-capture detector [687]. The reaction is specific for iodine, iodide being determined after oxidation with iodate. The nitrate anion can be determined in aqueous solution after conversion to nitrobenzene by reaction with benzene in the presence of sulfuric acid [688,689]. The detection limit for the nitrate anion was less than 0.1 ppm. The nitrite anion can be determined after oxidation to nitrate with potassium permanganate. Nitrite can be determined directly by alkylation with an alkaline solution of pentafluorobenzyl bromide [690]. The yield of derivative was about 80t.with a detection limit of 0.46 ng in 0.1 ml of aqueous sample. Pentafluorobenzyl p-toluenesulfonate has been used to derivatize carboxylate and phenolate anions and to simultaneously derivatize bromide, iodide, cyanide, thiocyanate, nitrite, nitrate and sulfide in a two-phase system using tetrapentylammonium cWoride as a phase transfer catalyst [691]. Detection limits wer Hi the ppm range. 

Using ethyl chloroformate as a reagent for C-8—N bond cleavage (Section II,A,4), synthesis of ( )-canadaline (272) from tetrahydroberberine (26) was independently achieved by Ronsch (40) and Hanaoka et al. (41,45). Bond-cleaved iodide 40a or chloride 40b was converted to the acetate 280 or the alcohol 281, both of which were easily derivatized to 272 through reduction of the urethane and oxidation of the alcohol 274 (Scheme 48). 

Chen S-H, Wu S-M, Kou H-S, et al. 1994. Electron-capture gas chromatographic determination of cyanide, iodide, nitrite, sulfide and thiocyanate anions by phase-transfer-catalyzed derivatization with pentafluorobenzyl bromide. J Anal Toxicol 18(2) 81-85. 

The O-methylated extract was derivatized with 99 percent C-enriched methyl iodide. The NMR spectrum of the extract showed a strong absorption at 56 ppm (relative to TMS), which can be attributed to unhindered aryl methyl ethers (67%), a smaller absorption at 60 ppm, attributable to hindered aryl methyl ethers (23%), and a resonance at 51 ppm, assignable to methyl esters derived from carboxylic acids (10%).(16) TTiese results are consistant with those of Liotta l al, who studied the alkylation of whole Illinois No. 6 coal.(12)... 

Bei der Verseifung der 2-Alkoxycarbonyl- bzw. 2-Aminocarbonyl-Funktion decarboxyliert das zunachst entstehende 2-Carboxy-l,3-dimethyl-benzimidazolium-iodidzu 1,3-Dimethyl-benziinid-azoUum-iodid (81% Schmp. 196 -198°). Das Cyan-Derivat solvolysiert allerdings in hoi Bern Methanol zu l,3-Dimethyl-2-oxo-2,3-dihydro-benzimidazol (67%)499 ... 

Bovine NHs/hydroxylamine kidney treatment, EtOAc extn, liq-liq partn, SPE cleanup, derivatization with methyl iodide, liq-liq partns... 

Figure 9 shows a commercial drug mixture in human urine underivatized and derivatized with methyl iodide. In Figure 9a the propoxyphene and methamphetamine are not observed from the urine. However, upon derivatization, molecular ions from both can be seen and the ion intensity from methadone and quinine have been increased by a factor of ten. 

Chemical Reactions. The pyridinium iodide derivatized samples... 

Perfluorinated alkyl radicals, generated by photoinduction from heptadecafluoro-octyl iodide, were added to SWCNTs and the perfluorooctyl-derivatized CNTs obtained (Scheme 1.14). No difference in the solubility of the fluoroalkyl-substituted nanotubes and the starting materials was observed [148]. A pathway to the radical functionalization of CNTs sidewalls was predicted by classical molecular dy-... 

Having determined the most appropriate extraction from plasma we investigated the simultaneous derivati-zation of A9-THC and ll-hydroxy-A9-THC. We have claimed that ethylation of 11-hydroxy-A9-THC proceeded by phase transfer catalysis (7). However, it is known that quaternary ammonium hydroxides are capable of catalyzing alkylations with alkyl iodides in aproptic solvents (8). Furthermore, we had not demonstrated that A9-THC could be derivatized under the same conditions as ll-hydroxy-A9-THC. We found that the minimum requirement for the reaction to proceed is the presence of water, which probably increases the degree of ionization of the quaternary ammonium hydroxide. However, in order for the reaction to go to completion, at least 0.1N NaOH is necessary. This supports the contention that this derivatization is, to some extent, a phase transfer catalyzed alkylation. 

Figure 6. Conditions for the derivatization of A9-THC with trifiuoroethyl iodide...

Metabolites of the dihydropyridines (including nimodipine) could be determined in urine through the use of gas chromatography-mass spectrometry after extractive methylation [14]. Derivatization was affected using methyl iodide. The derivative was dissolved in ethyl acetate, and was injected into a HP capillary (12 m x 0.2 mm ... 

Other derivatization procedures involve alkylation and silylation [486]. The latter is carried out with the aid of BSTFA and provides simple products, whereas alkylation with a methyl iodide—sodium hydride—dimethyl sulphoxide mixture (50°C, 10 min) leads to two peaks due to various products. 

For the preparation of derivatives on a micro scale (at the microgram and picogram levels) reaction with methyl iodide was recommended [510] 100—200 /il of an acetone solution of barbituric acids was mixed with a 3- to 1000-fold molar excess of methyl iodide and refluxed with 3—5 mg of potassium carbonate. After about 30 min, 0.2 /A of the supernatant was injected directly into a column with 3% of OV-225, with temperature programming at 8°C/min from 100 to 240°C. The advantage of the method is that no toxic and hazardous chemicals are used. The method was further modified for the micro-determination of barbiturates in blood [511]. Only 20-25 /d of blood were necessary for the determination, and with the use of a detector sensitive to nitrogen down to 1 ng of barbiturate could be determined in this sample. The derivatization reaction was performed in a micro-refluxer (see Fig. 2.6). 

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