Fatty acid hydrazides

An example of the application of a hydrazide in this general s5mthesis, amongst others 91, 391, 392, 416), is the reaction of isonicotinic acid hydrazide and cyanoguanidine in the presence of acid to yield isonico-tinoylaminobiguanide [C5H4CO NHNH C( NH) NHC NH) NHg] 391, 392, 416). Long-chain fatty acid hydrazides react similarly (655). 

Miwa et al. (26) have demonstrated that both short- and long-chain fatty acids can also be converted into their 2-nitrophenylhydrazides and separated bv RP-HPLC with acetonitrile-water as the eluent. They have described a method for the direct derivatization without an extraction step and the simultaneous microanalysis of 14 kinds of C 0 0-C22 6 fatty acid hydrazides in a reverse-phase HPLC system (27). 

The simultaneous separation of a mixture of 15 kinds of fatty acid hydrazides with mobile phases comprising various mixtures of methanol and water was not possible because of the long retention times. Figure 5 shows that with methanol-water (86 14) the separation of linoleic and eicosapentenoic acid hydrazides, and of linoleic, arachidonic, and docosahexenoic acid hydrazides, were difficult. 

The elution volumes of the fatty acid derivatives are affected principally by the number of carbon atoms and the number of unsaturated bonds in the fatty acid chains. In acetonitrile-water, unlike methanol-water, the number of unsaturated bonds seemed to be of greater importance. Also, the effect of the column temperature was important. A value of 30°C was used to shorten the analysis time, with good resolution. Thus, satisfactory resolution and favorable retention times (within 15 min) of the C 0 0-C22 6 fatty acid hydrazides were obtained in RP-HPLC with isocratic elution using acetonitrile-water (85 15), as shown in Fig. 5b. 

Recently, Rauf et al. (07ARK(xvi)137) have developed a microwave-mediated, solvent-free variant of the Neunhoffer chemistry that allows the preparation of 3,5,6-trisubstituted-l,2,4-triazines 13 from 1,2-dicarbonyls 2 and fatty acid hydrazides 12, rather than amidrazones (Scheme 4). In a similar microwave-mediated approach, Nongkhlaw s group utilises 1,2-dicarbonyls, amides and hydrazine to construct 1,2,4-triazines (08ARK(xv)79). 

Zeller, R, Hetscher, A., Gey, K. F., Gutmann, H., Hegedus, B., Staub, O. Amino acid and fatty acid hydrazides chemistry and action on monoamine oxidase. Ann. NY Acad. ScL 1959,80,555-567. 

Rauf and coworkers synthesized the 3,5,6-trisubstituted-l,2,4-triazines from fatty acid hydrazides nnder MW assisted solvent-free conditions [101] (Scheme 3.41). 

The use of pre-column HPLC method for the analysis of fatty acid with 2-nitrophenylhydrazine hydrochloride was reported (Miwa Yamamoto 1990). After alkaline hydrolysis of coconut oil free fatty acids are reacted with 2-nitrophenylhydrazine hydrochloride and then derivatized to corresponding fatty acid hydrazides. Each of the derivatives was separated on reversed-phase HPLC with isocratic elution and detected at VIS 400 nm (Miwa Yamamoto 1996). In Table 2 is presented the typical fatty acid composition of coconut oil. 

Isonicotinic acid hydrazide (INH) Hydrazine derivatives Fatty acid hydrazides, fatty acid aryl hydrazine sulfonic acids Polyhydrazino and amino hydrazine derivatives Phenyl hydrazine, rotenone derivatives, semicarbozones, thiosemicarbozones, sulfonic acid hydrazides 3-Amino-phthalyl hydrazide Phenyl hydrazine and unsymmetrical diphenyl hydrazine (UDPH)... 

An excellent example of PLC applications in the indirect coupling version is provided by the works of Miwa et al. [12]. These researchers separated eight phospholipid standards and platelet phospholipids from the other lipids on a silica gel plate. The mobile phase was composed of methylacetate-propanol-chloro-form-methanol-0.2% (w/v) potassium chloride (25 30 20 10 10, v/v). After detection with iodine vapor (Figure 9.2), each phospholipid class was scraped off and extracted with 5 ml of methanol. The solvent was removed under a stream of nitrogen, and the fatty acids of each phospholipid class were analyzed (as their hydrazides) by HPLC. The aim of this study was to establish a standardized... 

Miwa and Yamamoto (31) described a simple and rapid method with high accuracy and reliability for the determination of C8 0-C22 6 fatty acids, which occur in esterified forms in dietary fats and oils and in living cells [the biological effects of routinely consumed fats and oils are of wide interest because of their impact on human health and nutrition (28,29), in particular, the ratio of cu-3 polyunsaturated fatty acid to w-6 polyunsaturated fatty acids (w-3/cu-6) seems to be associated with atherosclerosis and breast and colon cancers (30)]. They report improved separation of 29 saturated and mono- and polyunsaturated fatty acids (C8-C22), including cis-trans isomers and double-bond positional isomers, as hydrazides formed by direct derivatization with 2-nitrophenylhydrazine hydrochloride (2-NPH HC1) of saponified samples without extraction. The column consisted of a J sphere ODS-M 80 column (particle size 4 /xm, 250 X 4.6-mm ID), packed closely with spherical silica encapsulated to reach a carbon content of about 14% with end-capped octadecyl-bonded-spherical silica (ODS), maintained at 50°C. The solvent system was acetonitrile-water (86 14, v/v) maintained at pH 4-5 by adding 0.1 M hydrochloric acid with a flow rate of 2.0 ml/min. Separation was performed within only 22 min by a simple isocratic elution (Fig. 6). The resolution of double-bond positional isomers, such as y-linolenic ( >-6) and a-linolenic acid ( >-3) hydrazides and w-9, >-12, and >-15 eicosenoic acid hydrazides was achieved by use of this column. 

Fig. 5 Chromatograms of the 2-nitrophenylhydrazides of a mixture of saturated and unsaturated long-chain fatty acids obtained with UV detection. Flow rate 1.2 ml/min. Eluent and column temperatures (a) methanol/water (86 14 v/v) and 50°C (b) acetonitrile/water (85 15 v/v) and 30°C. Peaks 1. capric 2. Laurie 3. myristoleic 4. eicosapentenoic 5. linolenic 6. myristic 7. docosahexenoic 8. palmitoleic 9. arachidonic 10. linoleic 11. eicosatrienoic 12. palmitic 13. oleic 14. margaric (internal standard) 15. stearic acid hydrazide. Each peak corresponds to 150 pmol.

Sucker control Maleic hydrazide higher alcohols and fatty acids (C8-C14)... 

Scavenger compounds that have been patented include unsaturated fatty acids [19], sulfonyl hydrazides [20], cyclopentadienes [21], styrene-butadiene block copolymers [22], peroxides [23], and terpenes [24],... 

Free Fatty Acids and Organic Acids Free fatty acids can be readily analyzed by RPC with an acidified mobile phase and detection at 210 nm.9 However, pre-column derivatization of free fatty acids to form derivatives such as p-bromophenacyl esters, 2-nitrophenyl hydrazides, or anthryl-methylesters, can improve the chromatographic performance and detection sensitivity by UV or fluorescence detection.9 Nevertheless, GC of their methyl esters remains the more common assay method. 

Hydrazino compounds can react with carboxy compounds in aqueous medium to form hydrazide. For the reaction to proceed under mild conditions, N-ethyl-N -(3-dimethylaminopropyl) carbodiimide (EDC) is required as a condensing reagent. Fatty acids are determined with 2-nitrophenylhydrazine hydrochloride (NPH) by LC-UV detection. The detection limits for long chain fatty acids are 2.5-5 pmol per injection. As FL derivatization reagents, 6,7-dimethoxy-l-memyl-2( lH)-quinoxalinone-3-propionyl carboxylic... 

In this way, azo dyes [638], dinitrophenylhydrazones [470], 2,4-dinitrophenyl-hydrazides of fatty acids [800], Kauwolfia alkaloids [607], aristolochia acids [507] and various polynuclear aromatic hydrocarbons [599] could be localised. 

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