Imino compound

Azoic Dyes. These are used to produce cost-effective heavy yellow, orange, red, maroon, navy blue, brown, and black shades and are ptinted alongside other dye classes to extend the coloristic possibiUties for the designer. Two approaches are adopted. The common method ia the United States is to use both a naphthol derivative and a stabilized color base, usually in the form of a diazo imino compound in the same print paste. This mixture is soluble in dilute caustic soda and no coupling takes place at this stage. The dried prints are passed through steam at 100—105°C that contains acetic and/or formic acid vapor. As neutralization takes place on the print, the coupling occurs rapidly and the insoluble azoic dye is formed. 

The electronic environment of an a-substituent on pyridine (319) approaches that of a substituent on the corresponding imino compound (320) and is intermediate between those of substituents on benzene and substituents attached to carbonyl groups (321, 322) (cf. discussion in Chapter 2.02). Substituents attached to certain positions in azole rings show similar properties to those of a- and y-substituents on pyridine. However, the azoles also possess one heteroatom which behaves as an electron source and which tends to oppose the effect of other heteroatom(s). 

Thus in the presence of an excess of NH4+, which suppresses this forward reaction, and counteranions such as NOa" and C104, which have little tendency to coordinate, complexes such as [Hg(NH3)4] +, [Hg(L-L)2] + and even [Hg(L-L)3] + (L-L = en, bipy, phen) can be prepared. But, in the absence of such precautions, amino, or imino-compounds are likely to be formed, often together. Because of this variety of simultaneous reactions and their dependence on the precise conditions, many reactions between Hg and amines, although first performed by alchemists in the Middle Ages, remained obscure until the application of X-ray crystallography and, still more recently, spectroscopic techniques such as nmr, infrared and Raman. 

Amino groups are considerably less acidic than hydroxyl groups, and in aliphatic chemistry imino compounds are generally far less... 

The structure of only one 1,2,4-thiadiazole salt has been determined. Unambiguous synthesis of the imino compound obtained on alkali treatment of the salt formed by the reactions of methyl iodide with 5-amino-1,2,4-thiadiazole established that the salt possesses structure 7 136 pjjjg quatemization exactly parallels the reaction occurring in... 

Aminopyrroles are usually formulated as such because they are quite strong bases and do not easily lose ammonia by hydrolysis. In agreement with the amino formulation, the infrared spectrum of the a-aminopyrrole 93 (R = H) contains a v NHg doublet and a band near 1660 cm" corresponding to the NH2 deformation frequency, and the infrared spectrum of the acetamino derivative is in agreement with the structure 93 (R Ac). However, a stable imino compound, probably with structure 94, has been isolated. ... 

Enolates derived from various imino compounds have been sulfinylated in reactions analogous to those shown by equations (14) and (15). Some representative examples are shown in equations 16-18. Here again, these compounds have been utilized in asymmetric syntheses. Addition of sulfinate ester 19 to a THF suspension of a-lithio-N,N-dimethylhydrazones, derived from readily available hydrazones of aldehydes and ketones, leads to a-sulfinylhydrazones in good yield, e.g. 53 and 54 (equations 16 and 17)85,86. Compounds 53 and 54 were obtained in a 95/5 and 75/25 E/Z ratio, respectively. The epimer ratio of compound 53 was 55/45. Five other examples were reported with various E/Z and epimeric ratios. 

This section covers fully saturated 5-5, 5-6, and 6-6 bicyclic stmctures including oxo, thioxo, and imino compounds as well as their benzo analogs. 

When the imino compound XIV is heated with dilute hydrochloric acid, hydrolysis of the imino group takes place and there is formed ammonium chloride and D-glucoascorbic acid (XV). The latter displays all the chemical properties of L-ascorbic acid. 

In another variation of a type E synthesis, thioamides or thioureas condense with /V,/V-dimcthylacylamide dimethyl acetal to give imino compounds which react with amino-transfer reagents like hydroxylamine-O-sulfonic acid and mesitylsulfonyloxyamine (MSH) to give 3,5-substituted-l,2,4-thiadiazoles in excellent yields <1996CHEC-II(4)307>. There have been no new reports of type E syntheses since the publication of CHEC-II(1996). 

Study of the aminodeethoxylation with N-labeled liquid ammonia shows that in the 4-imino compound no incorporation of the label has taken place, proving that in the replacement of the ethoxy group no ring opening is involved. It is unknown whether the aminodeethoxylation occurs according to routes (a) and (b) in the a-adduct 22 or in the starting material 21, which is present in only a small equilibrium concentration with 22 (Scheme III.13). One can expect, however, that despite its low concentration, the aminodeethoxylation reaction takes place in the pyrimidinium salt 21, being more reactive towards to nucleophiles than the neutral adduct 22. 

With ethyl cyanoacetate, the 9-oxo compound 79 X = O) is obtained. When the reaction is carried with malononitrile a similar rearrangement into the 9-imino compound 79 (X = N) takes place. 

Substituents on imino nitrogen influence both reactivity and enantioselectivity in hydrogenation of imino compounds. Figure 1.32 shows two successful examples. An f-BINAPHANE-Ir complex effects asymmetric hydrogenation of A-aryl aromatic imines.On the other hand, an Et-DuPHOS-Rh complex (see Figure 1.2) is effective for hydrogenation of A-acyUiydrazones. ... 

It may be assumed, therefore, that highly electronegative groups, such as CF2CI or CFg, stabilize the imino compounds. Similar observations were made with aliphatic and aromatic iminochloromethanesulfenyl chlorides the former are very unstable, but the latter are stable to some degree 190). 

Other examples this type of quinazoline synthesis include the formation of the thione analog 752, by displacement of bromine from thiourea 751 <2003ARK(x)434>, and the imino compound 754, which could be formed by heating the guanidine derivative 753 in DMF, without the need for any added base <2005RJ01071>. 

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