Schiff s base compounds

In addition, the two-iron Schiff s base compounds studied by Lewis et al. (160—162) have magnetic properties which indicate a structure which may be similar to that in the active centers of the plant-type ferredoxins. The following arguments set forth criteria on which to base any model for the active site ... 

Interactions with Histidine. Imidazole lactic acid and imidazole acetic acid were identified as breakdown products when histidine was reacted with methyl linoleate, methyl linoleate hydroperoxide or hexanal for 3 weeks at 25°C and 51°C (33). It was postulated that these compounds were formed via free radical reactions. Two other products were also produced which yielded histidine upon acid hydrolysis. These were thought to be Schiff s base compounds arising... 

Aldehydes undergo condensation with primary amines with the elimination of water to give compounds known as SchifF s Bases, which can also be used to characterise aldehydes. Benzaldehyde for example condenses readily with... 

Pyridoxal Derivatives. Various aldehydes of pyridoxal (Table 3) react with hemoglobin at sites that can be somewhat controlled by the state of oxygenation (36,59). It is thereby possible to achieve derivatives having a wide range of functional properties. The reaction, shown for PLP in Figure 3, involves first the formation of a Schiff s base between the amino groups of hemoglobin and the aldehyde(s) of the pyridoxal compound, followed by reduction of the Schiff s base with sodium borohydride, to yield a covalendy-linked pyridoxyl derivative in the form of a secondary amine. 

Aromatic nitro compounds are often strongly colored. They frequently produce characteristic, colored, quinoid derivatives on reaction with alkali or compounds with reactive methylene groups. Reduction to primary aryl amines followed by diazotization and coupling with phenols yields azo dyestuffs. Aryl amines can also react with aldehydes with formation of Schiff s bases to yield azomethines. 

Aminodiphenyl reacts with carbonyl compounds to form colored or fluorescent Schiff s bases with the elimination of water ... 

Secondar-y amines are prepared by hydrogenation of a carbonyl compound in the presence of a prirnar-y anine. An A-substituted imine, or Schiff s base, is an intermediate ... 

Schiff s base (Section 17.10) Another name for an imine a compound of the type R2C=NR. ... 

The process can be still more simplified. It is not always necessary to use a pre-formed Schiff s base. Often it is sufficient to bring the carbonyl compound and the amine together in an inert solvent and to add the peracid to the mixture later, - In this way oxaziranes can be obtained in good yield even if the Schiff s base is unknown or can only be obtained in poor yield. For example, formaldehyde gives with aliphatic amines usually only trimers of the Schiff s bases (4). On the other hand, the synthesis of 2-cyclohexyl-oxazirane (5) from cyclohexylamine, formaldehyde, and peracetic acid proceeded in 66%... 

Compounds which contain two oxazirane rings are obtainable from Schiff s bases of glyoxal or terephthalic dialdehyde, e.g. (6). A bifunctional oxazirane is also obtained from ethylene diamine and cyclohexanone (7)d ... 

Thus the diazirines could be related by a smooth reaction to a well investigated class of compounds. The three-membered ring structure of the diazirines was thus largely confirmed. They can be obtained from compounds which certainly have a three-membered ring structure [Eq. (54)] and are easily convertible into compounds which have equally well confirmed three-membered ring structures. The structure of the 1-alkyl-diaziridines (43) obtained by the Grignard reaction were confirmed by identification with known compounds, usually prepared by the reaction of Schiff s bases with chloramine [Eq. (32)]. The results of some of these reactions are collected in Table XII. 

Tin(II) chloride reduces aromatic nitro compounds to the corresponding amines, these then react with 4-(dimethylamino)-benzaldehyde to yield colored Schiff s bases. 

Indole chemiluminescence (J> p. 112, I80,i8ia)j can a]so be regarded as a special type of Schiff s base chemiluminescence, for the indole compounds very probably react via a hydroperoxide derived from the respective indolenine form. 

Preparation with aliphatic amines, on the other hand, may promote side reactions, converting portions of a pigment to compounds that are somewhat soluble in toluene. Toluene is the most important solvent for publication gravure printing inks. This preparative method reduces the viscosity of the printing ink. The pigment is thus partially converted to a soluble azomethine (Schiff s base), which is formed by reaction between the acetoacetic arylide and an aliphatic amine [5] ... 

To circumvent this problem, several methods have been developed (157). Probably, the most prominent method is treatment with sodium boro-hydride (0.1% in PBS, 30 minutes prior to staining). NaBILi is known to neutralize Schiff s bases through reduction of amine-aldehyde compounds into nonfluorescent salts. 

Of the other possible structures (95) of the condensation product, the Schiff s base (CXXX) is not resolvable, nor, because of the tautomeric nature of the guanidine system, is the four-membered ring compound (CXXXI). A compound of the improbable structure (CXXXII) should yield a copper complex, which the condensation products failed to do. 

Seong (2002) compared silylated (aldehyde) and silanated (amine and epoxy) compounds from several commercial sources to the performance of an antigen (IgG) microarray. In addition, the efficiency of phosphate-buffered saline (PBS) (pH 7.4) and carbonate (pH 9.6) printing buffers were compared. While the various slides and surface chemistries showed differences in their binding isotherms, they ultimately reached similar levels of saturation. Silylated (aldehyde) slides showed comparable loading in both buffer systems. Apparently, tethering of antibody to the surface by Schiff s base formation of the surface aldehyde and lysine residues on the protein was applicable over a broad pH. However, carbonate buffer increased binding of proteins on silanated surfaces. 

The Friedlander synthesis of quinolines has been adapted to give derivatives of compounds (279) and (280). The isomeric quinoline aldehydes (284) and (285) react with various ketones to give (286) and (287) (77CR(C)(284)459, 82JHC1289). Compound (286) has also been obtained starting from the Schiff s base derivative of (284) (81JHC925). 

Addition of ammonia and its derivatives to carbonyl compounds preparation of oximes and imine derivatives (Schiff s bases)... 

In many reactions, the dihydro compounds resemble their aliphatic analogues. Thus, when Z is nitrogen, (225) behaves as a benzylamine, (223 Z = NH) as an aromatic amine, and (226) as a Schiff s base. Similar comparisons apply when Z is oxygen or sulfur (223 Z = 0) is an aromatic ether, (225 Z = 0) is a dibenzyl-type ether, and (223 Z = S) is an aromatic sulfide. Some of this behavior is illustrated by the following examples. 

The mechanism of these reactions has been suggested to involve initial decomposition of the thiourea to isothiocyanate and amine, and the latter reacts with the carbonyl compound to form a Schiff s base. Condensation of the Schiff s base with the isothiocyanate present, followed by loss of H2S gives the observed products.336-338-340... 

Methylene groups of pyrylium cations also react under mild conditions with nitrosoben-zenes in the presence of acetic anhydride and an alkali metal salt, which plays an essential role in the formation of Schiff s bases (116). The latter are hydrolyzed to the carbonyl compound (117) (71BSF3603). It is possible to form potential dyes by treatment of pyrylium salts with ortho esters such as triethyl orthoformate. The reactants are heated together in acetic anhydride or pyridine and trimethine dyes of type (118) and (119) are formed (70JHC1395, 71JOC600, 59CB2309). 

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