Quinoline insolubles formation

Aromatic pitches were produced by treating CCB-distillate at 400°C, 410°C, 420°C, 430°C, and 440°C. We found that process temperature is a very important parameter in determining the rate of toluene and pyridine insoluble formation. It was also found that a relatively high temperature (around 430°C) is required to produce a pitch with a high liquid crystal content. Table II gives the composition of pitches produced at 400-440°C. Figure 1 illustrates graphically, the effect of process temperature on the rate of toluene, pyridine, and quinoline insolubles formation. 

Figure 1. Effect of process temperature on the rate of toluene, pyridine, and quinoline insolubles formation.

Figure 3. Effect of temperature on quinoline insolubles formation.

A number of methods are used to evaluate a data set to describe the kinetics of carbonization, such as determining the temperature/time dependence of viscosity, quinoline insolubles formation, or weight loss ... 

The specification requirements for electrode binder pitch, eg, high C/H ratio, high coking value, and high P-resin content, effectively ruled out pitches from gasworks or low temperature tars. The cmde tar is distilled to a medium-soft pitch residue and then hardened by heating for several hours at 385—400°C. This treatment increases the toluene-insoluble content and produces only a slight increase in the quinoline-insoluble (Ql) material, the latter by the formation of mesophase. 

Mesophase formation in coal-tar pitch is encouraged by a reduction of the natural quinoline-insoluble matter content, which resembles carbon black but is not optically anisotropic and is characterized by an atomic carbon hydrogen ratio of 4 1. In contrast, the atomic carbon hydrogen ratio of mesophase is about 2 1. 

Distillate fraction Number 4 (from Table I) was treated at 430°C for varying time (3, 4, and 5 hours). Increasing reaction time led to increasing pitch yield and the rate of toluene insolubles formation, but not quinoline insolubles. Table VI gives the yield and composition of pitches prepared from distillate fraction Number 4. 

Yellow powder or bronze-yellow micalike particles. M.p. 963° (in sealed tube) d 5.018. Heat of formation —51.8 kcal. per mole (25°). Solubility in HgO (g. NiBrg/lOO g. solution) 56.6 (19°C) 61.0 (100°C). Soluble in methyl and ethyl alcohols, acetone and quinoline insoluble in toluene. Crystal structure sublimed product, C 19 type unsublimed product, variable between C 6 and V19 types. 

Mesogenic pitch is a pitch with a complex mixture of numerous essentially aromatic hydrocarbons. It does not contain anisotropic particles detectable by optical microscopy. Mesogenic pitch is low in quinoline-insoluble fractions and capable of transforming into MPP during continuous heat treatment above 750 K by the formation of optically detectable carbonaceous mesophase. 

The liquid phase carbonization process can be categorized on the basis of the starting material alkane hydrocarbon, alkene hydrocarbon, aromatic hydrocarbon, and PAH. Consequently, the primary material for MCMBs typically contains a large amount of PAHs from coal pitch and heavy oil. Components in primary materials, such as pyridine insolubles (Pis), quinoline insolubles (QIs), and other additives, and reaction conditions affect the growth, formation, and structure of MCMBs. 

In the case of phosphoryl chloride, the primary products were 4-chloro-quinoline-3-carboxylates. As the quinoline-3-esters were very insoluble, the reaction products were hydrolyzed to quinoline-3-carboxylic acids, and the isomeric ratios were determined by H-NMR in trifluoroacetic acid. Thermal cyclization in Dowtherm A resulted mainly in formation of the 7-substituted isomer. In the case of chloro derivatives (250), only traces of 5-isomer could be detected. [Earlier, others observed and reported the formation of a small amount of the 5-isomer too (e.g., 46JA1204 47JA374]. 

Quinolines have also been prepared on insoluble supports by cyclocondensation reactions and by intramolecular aromatic nucleophilic substitution (Table 15.26). Entry 10 in Table 15.26 is an example of a remarkable palladium-mediated cycloaddition of support-bound 2-iodoanilines to 1,4-dienes. Reduction of the nitro group of polystyrene-bound 2-nitro-l-(3-oxoalkyl)benzenes with SnCl2 (Entry 11, Table 15.26) leads to the formation of quinoline /Y-oxides. These intermediates can be reduced to the quinolines on solid phase by treatment with TiCl3. 4-Quinolones have been prepared by thermolysis of resin-bound 2-(arylamino)methylenemalonic esters [311]. 

The mesophase prepared by this route is mainly insoluble in solvents like pyridine or quinoline. Thus, extraction techniques have been extensively used to determine the degree of the isotropic pitch/mesophase conversion and then the reaction kinetics. At 350 C, the formation of the mesophase is extremely slow. One week is required to achieve a 40 wt.% concentration of mesophase. At 400-450°C, one to forty hours are required to achieve a 50 wt.% concentration of mesophase. Finally, temperatures above 500 C are considered undesirable due to the risk of coke formation. The formation of pyridine and quinoline extractables, i.e., mesophase, has been reported to follow first order kinetics. 

The formation of the mesophase by this route has the disadvantage of requiring rather long processing times. An alternative route is the solvent route [18]. Isotropic aromatic pitches contain a separable fraction which, when heated at 230-400°C, develops an optically anisotropic liquid crystal phase in <10 minutes. This mesophase has been called a neomesophase since it is highly soluble in solvents such as pyridine or quinoline, while the mesophase derived by the thermal route is insoluble. The separable fraction of isotropic pitch is insoluble in solvents like benzene, toluene, or mixtures of toluene and heptane. Thus, it can be separated by solvent extraction from isotropic or heat soaked pitches (Figure 5, b and b ). 

The chlorides of the alkali- and alkaline earth metals are practically insoluble in the pure liquid solvents, because the low donor numbers do not allow extensive coordination of the cations to take place. Tetraalkylammonium chlorides and phosphorus(V) chloride act as chloride ion donors. Triethylamine, pyridine, quinoline, other N-bases and ketones give conducting solutions which have been interpreted as due to the formation of chloride ions ... 

Moore and MitchelH prepared soluble poly(enaminoester) (X) from a.a -bis(carbomethoxy) diacetyl benzene and aromatic diamines. The polymers were subsequently thermally cyclized (Conrad-Limpach reaction) to poly(quinolines) (XI), which is analogous to the conversion of poly(amic acids) to polyimides in terms of converting a soluble prepolymer to a stable polymer of cyclized, rigid ring structures with the formation of volatile by-products. The cyclized product however, was infusible and insoluble. 

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