Phthalic hydrazide

Similarly, 3- and 4-hydroxycinnolines and their derivatives exist predominantly in the 0X0 forms (7) and (8), as supported by both pjSTa values and UV spectral data. The oxo forms for 3-hydroxycinnolines have been further supported by IR data <76MI21200>. Phthalazin-4-ones exist in the oxo form and phthalic hydrazide in the monohydroxymonooxo... 

Phthalic hydrazide tautomerism, 3, 4 Phthalic thioanhydride reactions, 4, 824-825... 

Phthalic hydrazide has received even more attention than maleic hydrazide, the potential tautomerism having been discussed since 1925. Chemical evidence has been advanced both for the dioxo form and for the dihydroxy form 89, and it has been fur-... 

The hydrolytic cleavage is usually slow, and requires drastic reaction conditions. A more elegant method is presented by the Ing-Manske procedure, where the A-alkylated imide is treated with hydrazine under milder conditions. In addition to the desired amine 5, the cyclic phthalic hydrazide 6 is then formed ... 

Fluorescence is by far the most important emission in hydrazide chemiluminescence the possible involvement of triplet-singlet transfer in some cases is discussed below. The correct chemical pathway can be understood to mean in part that a hydrazide must be stable enough under the oxidative reaction conditions usually applied to ensure that only a small proportion of the hydrazide molecules are consumed in non-chemiluminescent oxidation reactions, 3.6-diamino-phthalic hydrazide 24, for example, should yield a highly fluorescent dicarboxylate dianion and therefore exhibit strong chemiluminescence. However, being a derivative... 

Table 1. Chemiluminescence and fluorescence efficiencies of some substituted phthalic hydrazides (after Brundrett, Roswell, and White 12>)...

Dialkylamino phthalic acids resulting from the chemiluminescence reaction of 4-dialkylamino-phthalic hydrazides cannot easily form a tris anion because deprotonation of the amino group is impossible. They should therefore not exhibit such a strong decrease in fluorescence efficiency at higher pH values. This can actually be concluded from the pH dependence of the chemiluminescence of the 4-dialkylamino-phthalic hydrazides and related compounds 97>. 

Similarly the N-methylacridone derivative 59 yielded chemiluminescence which was about a third that of 58. In this case the donor part of the molecule, i.e. the phthalic hydrazide, cannot produce a fluorescent product at all, but on its oxidation excited phthalate dianions very probably are produced 124>. From a series of other compounds of this type (60, 61, 62)... 

Intermolecvlax energy transfer is apparently involved in the anomalous chemiluminescence of phthalic hydrazide in aprotic solvent (DMSO/tert.BuOK/Og) 124) the energy of excited phthalated ianion is transferred to phthal-hydrazide monoanion which then emits at 525 nm with relatively low quantum yield. This phenomenon has not been observed in aqueous systems 2>. 

Maleic and Phthalic Hydrazides, Barbituric acid Deriv.s, Uracil Deriv.s... 

Polymer Stability in Base Solutions, There was little evidence of polyhydrazide degradation in normal handling of dilute or concentrated solutions. Upon storage of concentrated solutions for several months at room temperature marked degradation has been noted. Solutions of poly(tere-phthalic hydrazide) (9.1% in 10% tetraethylammonium hydroxide) showed a slight loss in inherent viscosity when wet spun into fibers in a process employing acidic coagulation baths ( inh f om 3.8 to 3.5 and 4.5 to 4.2). 

The preparation of hydrazides by interaction of esters and hydrazine hydrate is quite straightforward and proceeds in good yields. In many cases, simple addition of hydrazine hydrate to the liquid esters suffices to cause the precipitation of the hydrazide [62]. If the esters are insoluble or solids, a more prolonged treatment is required usually in the presence of an alcohol, as in the preparation of tere-phthalic hydrazide given below ... 

The well-known observation concerning the effect of substituents on the phthalic hydrazide system, that electron-releasing groups increase and electron-withdrawing groups reduce the chemiluminescence quantum yield, is not yet fully understood with respect to its physico-chemical meaning. Three possibilities arise ... 

That the donor and the fluorescing part of the molecules in (19) and (22) actually are separated can be demonstrated. As mentioned above unsubstituted phthalic acid hydrazide does not chemiluminesce, neither does 4-methyl phthalic hydrazide [36]. A mixture of phthalic acid hydrazide and N-methyl acridone gives no light on oxidation. The conjugate (19) chemiluminesces in the aprotic system with 8% of the luminol quantum yield (ca. 1 x 10" ), the emission matching... 

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