Carbazoles basicity

Crude oils contain nitrogen compounds in the form of basic substances such as quinoline, isoquinoline, and pyridine, or neutral materials such as pyrrole, indole, and carbazole. 

Although it has not been possible to study the protonation of isoindole itself, it is clear that isoindoles are more basic than indoles or pyrroles. For example, 2,5-dimethyl-1,3-diphenylisoindole (40) has a p/sTa of 4-2.05 protonation of isoindoles occurs at positions 1 or 3. The pK for protonation of indolizine (10) at position 3 is 4-3.94 and that for carbazole (41) for protonation on nitrogen is estimated at -6.0. 

The yellow colored, sparcely soluble 5-ethyl-2-methyl-l l/f-pyrido[3,4-u] carbazolium 347 isolated from Aspidosperma gilbertii exists as a hydroxide after filtration of the corresponding iodide over basic aluminum oxide. A short synthesis was described (80CB3245). The Pyrido[3,4-a]carbazole ring system is present in the alkaloid AG-1, whereas Cryptolepine (348) possesses the indolo[3,2-b]quinoline moiety (65MI1). 

A solution of 3.5 g 4-(2,3-epoxypropoxy)carbazole in 50 ml absolute alcohol is mixed with 30 ml isopropylamine and heated for 3 hours under reflux. When the reaction is finished, the reaction mixture is evaporated to dryness. The residue obtained is taken up in methylene chloride and chromatographed over an aluminum oxide column (300 g basic aluminum oxide, activity stage IV eluent methylene chloride). The eluted fractions are evaporated and the residue is dissolved in methanol and acidified with 2N ethereal hydrochloric acid. 

Examples of the nitrogen compounds commonly found in crude oil were included in Table 2. In the diesel fraction, the population comprises basic and non-basic compounds, such as quinoline, indole, and carbazole families. 

Carbazole is a non-basic nitrogen compound, whose removal via hydrotreating is limited by its low reactivity. The removal of nitrogen by hydrotreatment involves a number of steps that take place on the catalyst surface. The weak interaction of neutral nitrogen compounds with catalysts precludes carbazole and its derivatives from being denitro-genated and makes them the most recalcitrant components in HDN of gas oils [308], In fact, it has been found that the nitrogen content of hydrotreated gas oil from Athabasca bitumen was composed primarily of alkyl carbazoles [309],... 

Several species of the genus Pseudomonas have been isolated that degrade carbazole and its alkyl derivatives and a variety of other microorganisms have been reported to mineralize non-basic nitrogen compounds, including species of Bacillus, Xanthomonas, Burkholderia, Comamonas, Beijerinckia, Mycobacterium, and Serratia [310],... 

For the quinone imine cyclization of iron complexes to carbazoles the arylamine is chemoselectively oxidized to a quinone imine before the cyclodehydrogenation [99]. The basic strategy of this approach is demonstrated for the total synthesis of the 3-oxygenated tricyclic carbazole alkaloids 4-deoxycarbazomycin B, hyellazole, carazostatin, and 0-methylcarazostatin (Scheme 17). 

Since the late 1960s, several carbazole alkaloids oxygenated in the 3-position were isolated from diverse natural sources, the majority of which were isolated from different plant sources. However, in 1979, Moore et al. reported the isolation of two unusual, non-basic, 3-oxygenated carbazole alkaloids, hyellazole (245) and chloro-hyellazole (246), from the blue-green marine algae Hyella caespitosa (225). These alkaloids have structures entirely different from those of the carbazole alkaloids isolated from terrestrial plants. 

The tubingensins A (379) and B (380) showed activity against the widespread crop pest Heliothis zea, and display in vitro anti-viral activity against herpes simplex virus type 1 with IC50 values of 8 and 9 pg/mL, respectively (346) (see Scheme 2.100). Some bis-basic ethers of carbazoles are anti-viral. When tested against Encephala myocarditis viral infection, several N-ethyl substituted bis-basic carbazoles of the general formula 490 were shown to be active (448) (Scheme 4.9). 

The construction of the carbazole framework was achieved by slightly modifying the reaction conditions previously reported for the racemic synthesis (614). Reaction of the iron complex salt 602 with the fully functionalized arylamine 814 in air provided the tricarbonyliron-coordinated 4b,8a-dihydrocarbazole complex 819 via sequential C-C and C-N bond formation. This one-pot annulation is the result of an electrophilic aromatic substitution and a subsequent iron-mediated oxidative cyclization by air as the oxidizing agent. The aromatization with concomitant demetalation of complex 819 using NBS under basic reaction conditions, led to the carbazole. Using the same reagent under acidic reaction conditions the carbazole was... 

In the acetylation of carbazole using dimethylacetamide-phosgene in methylene chloride, attack was shown to occur mainly at nitrogen (93 7, N C-3) trifluoroacetylation proceeded exclusively at nitrogen. Carbazole was more reactive in this sense than indole and much more reactive than pyrrole, a result paralleling their respective basicities at nitrogen (see Section II,A,3). N-Acylation under these conditions is thought to involve... 

Reppe has shown that secondary amines of low basicity, such as carbazole, diphenylamine, indole, imidazole, and benzimidazole, and amides such as pyrrolidone react with acetylene in the presence of strong alkali to give vinyl derivatives [81, 83, 84a, b] (Eq. 30). As described by Reppe, these reactions are... 

Dyes, Dye Intermediates, and Naphthalene. Several thousand different synthetic dyes are known, having a total worldwide consumption of 298 million kg/yr (see Dyes and dye intermediates). Many dyes contain some form of sulfonate as —S03H, —S03Na, or — SC NH. Acid dyes, solvent dyes, basic dyes, disperse dyes, fiber-reactive dyes, and vat dyes can have one or more sulfonic acid groups incorporated into their molecular structure. The raw materials used for the manufacture of dyes are mainly aromatic hydrocarbons (67—74) and include benzene, toluene, naphthalene, anthracene, pyrene, phenol (qv), pyridine, and carbazole. Anthraquinone sulfonic acid is an important dye intermediate and is prepared by sulfonation of anthraquinone using sulfur trioxide and sulfuric acid. 

Apart from diphenylamine a number of other organic bases were tested for use as stabilizers. Some of them, e.g. aniline, were used only temporarily, chiefly during World War I when diphenylamine was in short supply. The basic properties of aniline are too marked and this is detrimental to stability. On the other hand, relatively good results have been obtained with carbazole which resembles diphenylamine in its structure ... 

The results of the infrared analysis are presented in Table VI. These results show that carboxylic acids and phenols are found only in the acid concentrates. Carboxylic acids are concentrated in the polar acid subfractions III and IV while phenols are concentrated in subfraction II. Carbazoles, ketones, and amides are found in all three major nonhydrocarbon fractions. The appearance of the same compound type in several fractions may arise from differences in acidity or basicity that are caused by the hydrocarbon portion of the molecule. Multifunctionality could also be a factor in the distribution of compound types among the fractions. The 1695 cm"1 band was assigned to ketones on the basis of work... 

The additional rejected claims, 2-8, were directed to additional, presumably narrower embodiments of claim 1. In rejecting claims 1-8 for alleged obviousness, the USPTO examiner (and majority of the USPTO Board that upheld the rejection) relied on a single piece of prior art from the chemical literature.26 The cited art related to a study of the local anesthetic properties of certain carbazoles, dibenzofurans, and dibenzothiophene derivatives. There were no bis-basic esters of carbazoles disclosed (only mono-basic esters), but there was one bis-basic ester of a dibenzofuran that was disclosed, having the structure shown in Figure 8.2. 

The bis-basic ester of the dibenzofuran from the cited art is structurally similar to the Markush genus disclosed in Albrecht s application but does not fall within it since the core structure is a dibenzofuran and that of Albrecht is a carbazole.27 This... 

In rejecting claims 1-8 of Albrecht s application, the examiner noted that certain mono-basic esters of carbazole were reported to have powerful local anesthetic activity, whereas the corresponding dibenzofuran compounds were less effective. The further disclosure of the bis-basic dibenzofuran as having some minimal anesthetic activity was sufficient, the examiner alleged, to motivate a PHOSITA to make the bis-basic esters of the carbazole compounds like those claimed in Albrecht s application, since the prediction would be that the bis-basic ester of the carbazole would be a more effective anesthetic than the disclosed bis-basic dibenzofuran. It would, therefore, be obvious to make these compounds, and the claims should be rejected. 

Unsubstituted polysaccharides do not appreciably absorb ultraviolet and visible radiation, but they can be made to do so intensely by combining them with chromophores and chromogens (e.g., a-naphthol, dihydroxynaph-thalein, anthrone, carbazole, phenol-sulfuric acid, 2-thiobarbituric acid, tolu-idine blue, diphenylamine, Congo red, aniline blue, and methyl orange), usually in acidic or basic media. Coloration is normally preceded by depoly-... 

In the first part of this chapter we review some basic concepts of photoconductivity which are followed by a renew of some experimental techniques and how these have been applied to characterize some of the well known polymeric systems such as poly(N-vinyl carbazole) (PVK) and the charge transfer complex of PVK and 2,4,7,trinitro-9-fluorenone (TNF). The second part of this chapter is a review of the extensive original and patent literature on a variety of photoconducting polymers. 

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