Amines ninhydrin

The formation of the imines and their subsequent reduction was monitored by the disappearance of the starting amine (ninhydrin staining, TLC). Simple quenching with water and drying of the organic solutions with MgS04 constituted the reaction work-up. The condensation of the amines with isothiocyanates and TEA was monitored by TLC (blue bromophenol staining, disappearance of... 

Ninhydrin amino acids, and amines 0.3% ninhydrin in n-BuOH with 3% AcOH, followed by heating to 125°C/10 min blue spots... 

Methylkasugaminide (5) by Cold Alkaline Hydrolysis of C9-Amine (3) with Barium Hydroxide. A solution of C9-amine (519 mg., 2.24 mmoles) dissolved in 5 ml. of water free from carbon dioxide was treated with 50 ml. of barium hydroxide saturated solution at room temperature for 48 hours. Generation of ammonia was observed and barium oxalate (241 mg., 0.99 mmole) was obtained. After removal of barium oxalate, barium carbonate produced by neutralization with dry ice was also removed by filtration. The filtrate thus obtained was placed on a column of Amberlite CG-50 (ammonium form, 1.5 x 25 cm.) and developed with water. After the similar treatment as described in the cold hydrolysis of kasugamycin, ninhydrin-positive fractions afforded a colorless crystalline material (154 mg., 0.62 mmole), m.p. 223°-225°C. (dec.), [ ]D20 +110° (c=1.7, H20), pK a 1.8 and 7.9, which was identified to be C9-acid (15). Anal. Calcd. 

The specific detection of aromatic nitro compounds is a second example. These can be converted by reduction to primary amines, which are then diazotized and coupled to yield azo dyes (cf. reagent sequence Titanium(III) chloride — Bratton-Marshall reagent ). Sodium nitrite —naphthol reagent, diazotized sulfanilic acid and other reagents specific for amino groups (e.g. ninhydrin, fluorescamine, DOOB, NBD chloride [9]) can also be used in the second stage of the reaction (Fig. 21). 

Ninhydrin (1,2,3-indantrione, 100 mg dissolved in 50 ml of methanol) transforms all samples containing molecules with NHj groups, such as amino acids, peptides, or amines, into red- or purple-colored products. To perform a reaction, at least 5 to 10 min heating at 120°C is necessary. 

Anchored amine materials can be prepared through a number of synthetic methodologies. Because of the potential importance of these materials to organic synthesis, a ninhydrin assay was developed as a rapid laboratory determination of available surface amines. The assay agreed well with expected values for aminopropyltriethoxysilane grafted onto commercial silica. The assay also distinguished between reactive amines and protonated or poisoned surface amines on co-condensed SBA-15 materials. 

Ninhydrin Assays. Ninhydrin tests were performed using a modified procedme of Taylor et al. " APS Silica (10-75 mg) of various loadings (0.857, 0.571, and 0.343 mmol NH2/g Silica) was added to phosphate buffer (5 mL, 100 mM, pH 6.5), and 1 mL of a 5% w/v solution of ninhydrin in ethanol was added to the sluny. After stirring for an hour in a boiling water bath, the mixture was allowed to cool slowly to room temperature. The silica was then filtered and washed three times with 70°C distilled water. The filtrate was collected, added to a volumetric flask, diluted to 100 mL, and the absorbance of this solution at 565 mu was measured using a UV-visible spectrophotometer. The reference solution was prepared as above with unmodified amine-free silica. Calibration standards were prepared with aliquots of a 1 mg/mL solution of APS in ethanol. 

Table 38.1. Ninhydrin assays for surface amines using grafted silicas. Determined from grafting synthesis and elemental analysis. "Typical standard deviations were...

Table 38.2. Ninhydrin assays for surface amines on APS-SBA-15 materials, all materials were alkylated after polymer removal determined from elemental analysis frefluxed in 10% HCl in ethanol for 24 hours stirred with 25 wt%...

Figure 38.3. Parity plot for ninhydrin titrations showing measured amine...

The ninhydrin assay clearly shows that only a fraction of the total amines react with ninhydrin, suggesting that most of the amines are either protonated (and therefore... 

The analysis of amino acids involves chromatographic issues similar to those encountered in analysis of simple amines. Underivatized amino acids have, with a few exceptions, weak UV absorbance and a strong tendency to interact with stationary phases in undesirable ways. Underivatized amino acids are normally separated with ion exchange chromatography, then visualized post-column by reaction with ninhydrin, o-phthaladehyde (OPA), or other agents. Underivatized tryptophan and the metabolites kynurenine, 3-hydroxykynurenine, kynurenic acid, and 3-hydroxyanthranilic acid, were separated on a Partisphere 5-p ODS column with fluorescent detection.121... 

The polyamines putrescine, cadaverine, spermidine, and spermine, which are seen at elevated levels in some victims of cancer, were separated on a Technicon (The Technicon Company Chauncey, NY) TSM Amino Acid Analyzer packed with an 8% divinylbenzene-co-polystyrene sulfonated resin with post-column ninhydrin detection.111 Amines such as ethanolamine, noradrenaline, hexamethylene diamine, methoxytryptamine, spermine, and spermidine were separated from amino acids on a DC-4A cation exchange resin.112 A similar approach, using a Beckman Model 121M amino acid analyzer equipped with an AA-20 column, was also successful.113 A Polyamin-pak strong cation exchange column (JASCO) was eluted with a citrate buffer for the detection of putrescene, spermine, cadaverine, and 1,5-diaminohex-ane from rat thymus.114 A post-column o-phthaldehyde detection system was used. 

Benson, J. R. and Hare, P. E., o-Phthalaldehyde fluorogenic detection of primary amines in the picomole range comparison with fluorescamine and ninhydrin, Proc. Natl. Acad. Sci. U.S.A., 72, 619, 1975. 

Normally the reaction Is useful for the conversion of alkyl halides to primary amines without concomitant formation of secondary amines.29 Treatment of polymer 17 with hexamethylenetetramine in a mixture of ethanol/THF afforded an insoluble resin. Using diazabicyclooctane (DABCO), we demonstrated that the reaction could be limited to attack by a single nitrogen in a multifunctional amine, so we did not anticipate crosslinking via bis-quat salt formation. Hydrolysis of 2 with anhydrous HC1 in ethanol generated free amino groups as evidenced by a positive ninhydrin test, but quantitative hydrolysis could not be achieved and the product remained insoluble. One would have expected a simple bis-quat to hydrolyse and open the crosslinked structure. 

FIGURE 5.6 Reaction of ninhydrin (trioxohydrindene hydrate) with the amino group of a bound residue (A) generates the Schiff s base. Hydrolysis after shift of the double bond generates the aldehyde and another amine which reacts (B) with a second molecule of ninhydrin to give an equilibrium mixture of the anion depicted and its tetraoxo form with a maximum of absorbance at 570 nm. 

Amines other than a-amino acids will also give a colour reaction with ninhydrin but without the production of carbon dioxide. Thus /3-, y-, 8- and e-amino acids and peptides react more slowly than a-amino acids, to give the blue complex, while imino acids result in the formation of a yellow-coloured product which can be measured at 440 nm. Removal of substances such as protein, ammonia and urea from biological samples may be necessary in quantitative work because they also react in a similar manner. 

All primary amines react with fluorescamine under alkaline conditions (pH 9-11) to form a fluorescent product (Figure 10.12) (excitation maximum, 390 nm emission maximum, 475 nm). The fluorescence is unstable in aqueous solution and the reagent must be prepared in acetone. The secondary amines, proline and hydroxyproline, do not react unless they are first converted to primary amines, which can be done using A-chlorosuccinimide. Although the reagent is of interest because of its fast reaction rate with amino acids at room temperature, it does not offer any greater sensitivity than the ninhydrin reaction. 

Ehrlich p-Dimethylaminobenzaldehyde (100 g l"1) in cone. HC1. Mix 1 volume with 4 volumes of acetone. No heat required. Reacts within 20 min Trp Citrulline Pink/red Yellow Some indoles, aromatic amines and ureides react. Use after ninhydrin in multiple-dip sequences... 

Problems such as diffusional limitations and the analysis of catalyst composition occur with solid-phase catalysts. Much work has been done on diffusion in bound enzymes (for reviews, see 24 and 88). In our work we used ninhydrin, which is a reagent ideal for surface analysis amino acid analysis is used wherever possible. Amine depletion as followed by ninhydrin is not exact, but some quantitative guides are obtained. Certainly synthetic catalysts must be made with bonds other than amide bonds and components other than those compounds that are detectable on the amino acid analyzer. 

The classical post-column derivatization, as developed by Moore and Stein, 3 uses ninhydrin and detection is achieved at 570 nm for primary amine derivatives and at 440 nm for secondary amine derivatives with detection limits that strongly depend upon the instrumentation used. 

Green, N.R. Savage, J.R. (1978) Screening of safrole, eugenol, their ninhydrin positive metabolites and selected secondary amines for potential mutagenicity. Mutat. Res., Sl, 115-121... 

In a subsequent paper on the use of the Stille reaction to form biaryls,58 the reaction was carried out under ambient conditions to allow robotic automation of the process. Attachment of the tin species to resin was very straightforward, in that 4-tri-n-butylstannylphenyl acetic acid was linked to Rink amide resin simply using a DIC coupling. Loading of this species was determined by tin elemental analysis and correlated with a quantitative ninhydrin test of free amines remaining on the support (Scheme 24). 

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