From Ninhydrin

Diisopropyiethyiamine [7087-68-5] M 129.3, b 127 , pKe i -10.9. Distd from ninhydrin, then from KOH [Dryland and Sheppard, J Chem Soc, Faraday Trans I 125 1986]. It is a strong base and should be stored in the absence of carbon dioxide. 

Sequanal-grade triethylamine, obtained from Pierce Chemical Company, Rockford, Illinois, was distilled under nitrogen from ninhydrin, which was also purchased from Pierce Chemical Company. 

Cyclobutanecarboxylic acid, 98%, is from Aldrich Chemical Company, Inc., and is vacuum distilled before use. Tetrahydrofuran is freshly distilled from sodium-benzophenone under nitrogen. N-Methyiraorpholine, 99%, is from Aldrich Chemical Company, Inc., and is pre-dried over barium oxide, distilled from ninhydrin, and stored over sodium hydroxide pellets. Ethyl chloroformate, 97%, is from Aldrich Chemical Company, Inc., and is freshly distilled prior to use under a nitrogen atmosphere. Anhydrous ammonia (99.99% min) is from a Matheson lecture bottle. The silica gel used for flash chromatography is... 

Diisopropylethylamine [7087-68-5] M 129.3, b 127". Distd from ninhydrin, then from KOH [Dryland and Sheppard, JCSFT1 125 1986]. 

The reduction of 2, either catalytically or with zinc in acetic acid, leads to 3-amino-4-hydroxy-2-quinolone 20 [72TH000], These amino compounds are rather unstable they dimerize with loss of ammonia to "bis-amines", which in turn are readily oxidized to dyes similar to those obtained from ninhydrin and primary amines [68M1205] [68M1543], The amino derivatives 20 are therefore conveniently converted into 0,N-diacetyl derivatives, the N-acetyl derivative 21, or its dehydrated form, the oxazolo derivative 22 [95MI000], The variety of biological activity of oxazolo-quinolines of type 22 has been detected only in recent years [94JHC1647],... 

Estimates of biomass from ninhydrin-reactive N measurements (Amato and Ladd 1988) have many advantages. The method is extremely quick (involving a simple colorimetric determination, thus avoiding a tedious digestion step), reliable, and accurate. Biomass measurements of ninhydrin-reactive N (Bnin) are also closely correlated with total biomass N (BN)... 

Indanocyclone (1). Mol. wt. 2fi6..11, m.p. 205 206°. Prepared from ninhydrin and diben yl ketone and cthanolic potassium hydroxide. ... 

Apart from ninhydrin, many other derivatization reagents have been used both precolumn and postcolumn derivatization modes have been extensively employed [3-5]. Derivatization procedures offer significant advantages in both separation and detection aspects and, thus. 

The reaction of m- and -substituted phenols with the tetrone 22, readily obtained from ninhydrin and 1,3-indanedione, leads to highly substituted 4//-chromenes <04T10197>. 

Two solutions are required and can be prepared as follows, (a) Mix 40 g of phenol with 10 mL of absolute ethanol. Warm until dissolved. Stir with 4 g of Amberlite mixed-bed resin MB-3 for 45 min and filter. In a separate vessel, dissolve 65 mg of KCN in 100 mL of water. Dilute 2 mL of this solution to 100 mL with pyridine (freshly distilled from ninhydrin). Stir with... 

Apart from ninhydrin, many other derivatization reagents have been used both precolumn and postcolumn derivatization modes have been extensively employed. Derivatization procedures offer significant advantages in both separation and detection aspects and, thus, will be discussed in further detail. The rest of the entry will be divided into two sections separation of underivatized amino acids, where the determination of free amino acids and postcolumn derivatization procedures are described and separation of derivatized amino acids, where precolumn derivatization approaches are discussed. 

A combination of the ninhydrin- and chlorination techniques is especially good. The layers are sprayed first with ninhydrin and the positions of the spots marked. Treatment with chlorine gas is then carried out as described above the previous treatment with ninhydrin does not affect the results. Spots appearing only on halogenation are thus easily distinguished from ninhydrin-positive compounds. 

In the first new example, 1,1,1-trichloroethanol was used together with TPP and DAAD to afford a p-trichloroethoxy phosphorane that on Wittig reaction with the trioxo derivative formed from ninhydrin by dehydration afforded dialkyl 2-(l,3-dihydro-l,3-dioxo-2H-indane-2-yliden-)3-(2,2,2-trichloroethoxy)succinates as electron-poor alkenes (Scheme lO ). " ... 

Fig. 14. Amount of hydrolysis given as moles of amino acid liberated (from ninhydrin color) per mole of mercuripapain (80). Molar ratio of enzyme (LAP) to substrate (MP) given as E/S on the basis that the molecular weight of LAP is 15 times that of MP. Extent of hydrolysis was determined after incubation at 40° for 24 hours at pH 8.5 0.1 in the presence of 0.001 M MgCL and 0.005 M Veronal or Tris buffer. Highly purified preparations of LAP were used after treatment with diisopropyl fluorophosphate.

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