Hydrazones compounds

This method describes the quantitative determination of carbonyl compounds in fats and oils. It is based upon the formation of 2,4-dinitrophenylhydrazones of carbonyl compounds in the presence of a trichloroacetic acid (TCA) catalyst, followed by colorimetric determination of the hydrazone compounds (i.e., as quinoidal ions) in an alkanolic basic solution. 

An analogous approach has been used in assigning H and 13C NMR chemical shifts in anthracenedione phenylhydrazones,50 l,3-bis(phenylazo)-2-naphthol and its precursors.51 Azo and hydrazone compounds 13 derived from Fischer base (l,3,3-trimethyl-2-methylidene-2,3-dihydroindole) were studied by two groups.52,53... 

Figure 65 The field dependencies of the hole mobilities of a series of hydrazone compounds in PC.

Figure 66 The temperature dependencies of the hole mobility of the hydrazone compound designated as CT6 in Fig. 65 in PC. The field dependence of the activation energy is shown in the inset.

There have been several attempts to relate mobilities to ionization or oxidation potentials (Enokida et al., 1990 Scott et al., 1990 Kanemitsu et al., 1991, 1992 Kitamura and Yokoyama, 1991). Scott et al. studied a series of hydrazone compounds in a polyarylate. The oxidation potentials of the donor compounds varied from 0.53 to 1.04 V. The results showed that the zero-field mobilities increase with increasing oxidation potential. In contrast, Enokida et al. investigated a series of butadiene, hydrazone, and oxadiazole compounds doped into a PC and concluded that the mobilities increased with decreasing ionization potential. Kitamura and Yokoyama studied a series of hydrazone compounds in a PC and concluded that the mobilities were independent of the ionization potential. While the reason for these discrepancies is not clear, it should be noted that the study of Scott and coworkers involved zero-field... 

Aldehyde and Ketone Reactions.—(i) The formation of addition prodmts with hydrogen cyanide, H—CN. (2) The formation of oxime compounds with hydroxyl amine, H2—NOH. (3) The formation of hydrazone compounds with a benzene compound known as phenyl hydrazine, H2N—NH—CeHs. 

Bisulphite compounds of aldehydes or ketones oximes semicarbazones hydrazones compounds containing the group -CHCI2. 

Aldehydes and ketones may be converted into the corresponding primary amines by reduction of their oximes or hydrazones (p. 93). A method of more limited application, known as the Leuckart Reaction, consists of heating the carbonyl compound with ammonium formate, whereby the formyLamino derivative is formed, and can be readily hydrolysed by acids to the amine. Thus acetophenone gives the i-phenylethylformamide, which without isolation can be hydrolysed to i-phenylethylamine. 

Reagent A is particularly useful for the treatment of the lower aliphatic aldehydes and ketones which are soluble in water cf. acetaldehyde, p. 342 acetone, p. 346). The Recent is a very dilute solution of the dinitrophenylhydrazine, and therefore is used more to detect the presence of a carbonyl group in a compound than to isolate sufficient of the hydrazone for effective recrystallisation and melting-point determination. 

When ethyl acetoacetate is warmed with an equivalent quantity of phenyl-hydrazine, the compound (I), which is not a true hydrazone, is first formed this undergoes ring formation (II) with loss of ethyl alcohol upon further heating. The product (II) is N or l-phenyl-3-methyl-5-pyrazolone. 

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

Reaction of dnnamaldehyde 4.35 with (2-pyridyl)hydrazine (4.36) yielded the desired hydrazone 4.37. As anticipated, this compound coordinates readily to copper(II)nitrate in aqueous solution as... 

Other interesting regioselective reactions are carried out within the synthesis of nitrofurantoin. Benzaidehyde semicarbazone substitutes chlorine in chloroacetic ester with the most nucleophilic hydrazone nitrogen atom. Transamidation of the ester occurs with the di-protic outer nitrogen atom. Only one nucleophilic nitrogen atom remains in the cyclization product and reacts exclusively with carbonyl compounds. 

Alkylidenehydrazinothiazoles (297) can be prepared either from 2-hydrazinothiazoles (549) or by direct heterocyclization (527). Their characteristic infrared bands have been reported (550). The main mass spectrometric peaks of (4-coumarinyl-2-thiazolyl)hydrazone (302) (Scheme 179) (134, 551) are situated at mle = 361. 244, 243, 118, 216, 202, 174, 117 the proposed interpretation of the fragmentation pattern should, however, be reconsidered. Scheme l80 summarizes some representative reactions of this class of compounds. 

Hydrazones are formed from mono- and Ai,A/-disubstituted hydrazines. Hydrazine itself can give either hydrazones or azines, depending mainly on the ratio of carbonyl component to hydrazine. The ease of formation of these compounds depends on the nature of the carbonyl constituent ... 

Many of these compounds ate highly colored and have found use as dyes and photographic chemicals. Several pharmaceuticals and pesticides are members of this class. An extremely sensitive analytical method for low hydrazine concentrations is based on the formation of a colored azine. They are also useful in heterocycle formation. Several reviews are available covering the chemistry of hydrazones (80,89) and azines (90). 

Hydroxybenzaldehyde has extensive use as an intermediate in the synthesis of a variety of agricultural chemicals. Halogenation of Nhydroxybenzaldehyde, followed by conversion to the oxime, and subsequent dehydration results in the formation of 3,5-dihalo-4-hydroxybenzonitrile (2). Both the dibromo- and dhodo-compounds are commercially important contact herbicides, hromoxynil [1689-84-5] (2) where X = Br, and ioxynil [1689-83-4]( where X = I respectively (74). Several hydrazone derivatives have also been shown to be active herbicides (70). 

Carbon—nitrogen double bonds in imines, hydrazones, oximes, nitrones, azines, and substituted diazomethanes can be cleaved, yielding mainly ketones, aldehydes and/or carboxyHc acids. Ozonation of acetylene gives primarily glyoxal. With substituted compounds, carboxyHc acids and dicarbonyl compounds are obtained for instance, stearoHc acid yields mainly azelaic acid, and a smaH amount of 9,10-diketostearic acid. 

Hydroperoxides have been obtained from the autoxidation of alkanes, aralkanes, alkenes, ketones, enols, hydrazones, aromatic amines, amides, ethers, acetals, alcohols, and organomineral compounds, eg, Grignard reagents (10,45). In autoxidations involving hydrazones, double-bond migration occurs with the formation of hydroperoxy—azo compounds via free-radical chain processes (10,59) (eq. 20). 

Oxidative Couplings of Heterocyclic Hydrazones. This method has opened the way to the preparation of azo derivatives of diazo compounds unobtainable by other means, ie, heterocycHc compounds ia which the diazotizable amino group is conjugated with the heterocycHc nitrogen atom as ia 2- and 4-amiQopyridine, compounds which do not normally yield stable diazonium salts (38). The reaction occurs as illustrated by equation 7 for the iateraction of (A/-methylcarbostyryl)hydrazone [28219-37-6] and dimethyl aniline the overall process is oxidation. 

Unsaturated hydrazones, unsaturated diazonium salts or hydrazones of 2,3,5-triketones can be used as suitable precursors for the formation of pyridazines in this type of cyclization reaction. As shown in Scheme 61, pyridazines are obtainable in a single step by thermal cyclization of the tricyanohydrazone (139), prepared from cyanoacetone phenylhydrazone and tetracyanoethylene (76CB1787). Similarly, in an attempted Fischer indole synthesis the hydrazone of the cyano compound (140) was transformed into a pyridazine (Scheme 61)... 

Special reactions of hydrazides and azides are illustrated by the conversion of the hydrazide (205) into the azide (206) by nitrous acid (60JOC1950) and thence into the urethane (207) by ethanol (64FES(19)105Q) the conversion of the same azide (206) into the N-alkylamide (208) by ethylamine the formation of the hydrazone (209) from acetaldehyde and the hydrazide (205) and the IV-acylation of the hydrazide (205) to give, for example, the formylhydrazide (210) (65FES(20)259). It is evident that there is an isocyanate intermediate between (206) and (207) such compounds have been isolated sometimes, e.g. (211). Several of the above reactions are involved in some Curtius degradations. 

Alloxan forms an oxime (1007) which is the same compound, violuric acid, as that formed by nitrosation of barbituric acid likewise, a hydrazone and semicarbazone. Reduction of alloxan gives first alloxantin, usually formulated as (1008), and then dialuric acid (1004 R = OH) the steps are reversible on oxidation. Vigorous oxidation with nitric acid and alkaline hydrolysis both give imidazole derivatives (parabanic acid and alloxanic acid, respectively) and thence aliphatic products. Alloxan and o-phenylenediamine give the benzopteridine, alloxazine (1009) (61MI21300). 

Hydrazino groups are also converted into H-compounds with mercury(II) oxide (74CR(C)-(278)427) in other reactions they have given hydrazones, or have been converted into pyrazoles and fused heterocyclic rings (77JAP(K)7785194), e.g. (72) -> (73). 

Analogous to the oxidation of hydrazones to azo compounds, A-unsubstituted pyrazolidines are oxidized to A -pyrazolines. For example, the blcyclic pyrazolidine (415) when treated with silver oxide yields the pyrazoline (416) (65JA3023). Pyrazolidine (417) is transformed into the perchlorate of the pyrazolium salt (411) by reaction with mercury(II) acetate in ethanol followed by addition of sodium perchlorate (69JOU1480). 

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