Hydrazine derivatization

II R2P-CI Hydrazin-Derivat Phosphinsaure-hydrazid Ausbeute [%] Schmp. rc] Lite- ratur... 

Colorometric procedures involving reaction of aldehydes with hydrazines, semicarbazide, or piperidine/nitroprusside solutions are also non-specific and lack sensitivity (15, 35, 36). Schmidt et al. (33) have proposed an HPLC method for analyzing the 2,4-dinitrophenylhydrazone (DNPH) derivatives of specific aldehydes. This procedure allows for a number of ddehydes to be separated and measured simultaneously, however, HPLC methods in general suffer from poor resolving power and may have low sensitivity (37). In addition, hydrazine derivatizations are often performed under acidic conditions for maximal reactivity these conditions would not provide quantitative information on total aldehyde content. 

Stereoselektiv verlauft die Herstellung von myo-lnosadiamin-l,3-Bis-hydrochlorid (91% d.Th.) aus dem entsprechenden iiberbriickten Hydrazin-Derivat I6. 

Endprodukt der Reduktion von Stickstoff-Verbindungen mit Jodwasserstoff sind die Amine, wobei je nach Reaktionsbedingungen das Nitroso-(Oxime), Hydroxylamin- bzw. Hydrazin-Derivat abgefangen werden kann. 

Malondialdehyde (MDA) is a secondary carbonyl compound that arises from lipid peroxidation pathway. Gas chromatographic analysis of pentafluorophenyl-hydrazine derivatized carbonyl compounds was successfully used to assess antioxidant activity of vegetable oils (Stashenko et al., 1997). 

Derivatization is useful for detection of compounds such as amino acids and amines that lack easily detectable groups. For similar reasons, saccharides, as a class of compound, ehcit much interest. Two derivatization schemes have been reported using benzamide (61) and FMOC—hydrazine (62) to produce fluorescent products. 

Hydrazine in air Lab method using sampling either onto acid-coated glass-fibre filters followed by solvent desorption or into specially constructed impingers. Linal analysis by derivatization and high performance liquid chromatography 86... 

Sanofi-Synthelabo researchers discovered pyrazole 53 and analogs to have potent Cannabinoid receptor-1 (CB-1) antagonist/inverse agonist activity and have progressed 53 into development for treatment of obesity and alcohol dependence. The synthesis of 53 was accomplished by heating the diketone sodium salt 51 with the aryl hydrazine hydrochloride in acetic acid to provide the intermediate 52, which was further derivatized... 

Several alternative routes can be used in order to derivatize the carboxy function (Fig. 7-7). Ketones can be transferred by hydrazines and diols to the corresponding hydrazines or acetals. 2,2,2-Trifluoro-l-phenylethylhydrazine [19] is an example of the first group, while 2,3-butanediol or l,4-dimethoxy-2,3-butanediol can be used to form diastereomeric acetals. 

Bei bicyclischen l,l-Dichlor(Dibrom)-cyclopropanen erhalt man als Reduktionspro-dukt iiberwiegend das exo-Chlor(Brom)-Derivat I (61-100%) bei 80-90% d.Th. Total-ausbeute. Reduziert wird in geteilter Zelle an Quecksilber (in DMF oder Methanol mit Li-thiumchlorid, auch mit Zusatz von Wasser oder Salzsaure Anolyt identisch mit zus. 10% Hydrazin)5 ... 

In saurer Losung wird Methyl-phenyl-nitrosamin an Blei zu N-Methyl-N-phenyl-hydra-zin reduziert (80% d.Th.)4. Analog verhalten sich Dialkyl-nitrosamine ( — 0,9 V, bis 82% d.Th.) in alkoholischer Salzsaure5. Zur Hcrstellung von N,N-Dimethyl-hydrazin aus dem N-Nitroso-Derivat s.ds. Handb., Bd. X/2, S. 42 (zuN,N-Dialkyl-hydrazinen s.Lit.6). 

The creation of hydrazide probes often is based on the derivatization of a detectable molecule with a fezs-hydrazide compound. Although hydrazine itself (in the form of hydrazine hydrate) can be used in a methanolic solution to modify activated carboxylate molecules forming hydrazides, the availability of the bifunctional hydrazides provides a built-in spacer to accommodate greater steric accessibility. 

Add to the glycan solution the molecule to be labeled containing an available amine, hydrazine, or hydrazide group. For small molecule derivatization, the final concentration of the nucleophile in the glycan solution should be about 0.3 M to result in maximal efficiency of labeling. For protein modification, an aqueous reaction buffer should be used, and the protein should be as concentrated as possible. 

Figure 14 Representative fluorescence derivatization reagents used for PO-CL detection. DNS-CI, dansyl chloride DBD-F, 4-(A,A-dimethylaminosulphonyl-7-fluoro-2,l, 3-benzoxadiazole NDA, naphthalene-2,3-dicarboxaldehyde DNS-H, dansyl hydrazine DBD-H, 4-(iV,iV-dimethylaminosulphonyl-7-hydrazino-2,l,3-benzoxadiazole).

Aminolysis of activated forms by methylamine provides a convenient derivative for characterizing activated forms. Boc-valine methylamide (Figure 7.37) was the derivative made to confirm the structure of the 2-tert-butoxy-4-isopropyl-5(4//)-oxazolone that had been prepared for the first time (see Section 1.18). However, for activated forms that might undergo enantiomerization or epimerization during aminolysis, hydrazinolysis is the reagent of choice for their derivatization and for establishing the isomeric nature of a substance. Reaction with hydrazine produces... 

Hydrazine may be derivatized with salicylaldehyde to a hydrazone derivative, separated on a suitable HPLC column and determined by a UV detector. Aqueous samples may be directly injected into a polar GC column interfaced to an FID. Anhydrous hydrazine may be appropriately diluted in alcohol or ether and determined by GC/MS. The molecular ion for GC/MS determination by electron-impact ionization is 32. 

Biotin does not exhibit UV absorbance. It neither shows fluorescence nor electrochemical activity. Therefore, it needs to be derivatized. 4-Bromomethylmethoxiycoumarin (BMMC) [590], 9-anthryldiazomethane (ADAM) [591], and 1-pyrenyldiazomethane (PDAM) [592] have been used as precolumn reagents to convert biotin to fluorescent absorbing derivatives. Instead, to obtain derivatives that are UV detectable, hydrazines are used, such as 2-nitrophenylhydrazine hydrochloride... 

NPH HCl) with l-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC HCl) as a coupling agent [593,594], The advantage is that with hydrazines it is possible to carry out the derivatization in milder conditions. An efficient postcolumn derivatization is obtained using avidin or streptavidin. In fact, these two proteins react in a very specific way with biotin, therefore they are bound with a fluorescent marker, such as fluorescein 5-isothiocyanate (FITC) to obtain fluorescent derivatives. Some authors [595] report the use of MS or MS/MS for biotin detection, but this method seems to be less sensitive than FLD. 

Der Ersatz einer Benzylthio-Gruppe in N-Heterocyclen wie z. B. Purin-Derivaten kann durch Erhitzen in waBrigem Hydrazin (- 6-Hydrazino-Derivat, 88%) und anschlieBendes Kochen in Wasser in Gegenwart von Raney-Nickel erfolgen (70%)1 z. B. ... 

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