Unisol process

Unisol process. In this process, mixture of caustic soda and methanol removes mercaptans from gasoline. 

Unisol process a chemical process for extracting mercaptan sulfur and certain nitrogen compounds from sour gasoline or distillates using regenerable aqueous solutions of sodium or potassium hydroxide containing methanol. 

The Unisol process (22, 47, 107, 122) uses methanol as the added agent to improve the caustic soda solution. Since it is soluble in gasoline, the flowsheet must be arranged to remove it, as in Fig. 11.8. H2S-free gasoline is extracted with aqueous caustic-methanol in the lower part of the packed extraction tower, and the methanol is extracted from the treated gasoline by aqueous caustic in the upper part. The combined caustic-methanol... 

Treatment of 4 with either PF3 or 13CO results in CO substitution believed to proceed via a dissociative process yielding Ti(CO)2(PF3)-(dmpe)2 (6) and Ti(13CO)3(dmpe)2. Structural characterization of 6 showed it also to be monomeric, but possessing a monocapped trigonal prismatic geometry. Complexes 4, 5, and 6 may be considered phosphine-substituted derivatives of the as yet unisolated Ti(CO)7, thus representing the only isolable titanium carbonyl complexes where the titanium atom is in the zero oxidation state. 

Unisol A process for extracting organic sulfur and nitrogen compounds from petroleum fractions by solvent extraction with aqueous sodium or potassium hydroxide containing... 

Arylhydrazones of A -acylbenzimidazoles (441) react with perchloric acid to rearrange into 1,2,4-triazolium salts 443, which can be isolated when R = Ar = Ph (Scheme 70). The protonated cycloadduct 442 represents a key intermediate. A reverse process was also pointed out neutralization of the triazolium salt 443 (R = Ar =Ph) with aqueous sodium carbonate gives back the corresponding 441, likely via a preliminary heter-ocyclization into a neutral cycloadduct. When R is a COMe or COOEt the unisolated triazolium salts 443 transform into final products by a condensation between the amino group and COMe or COOEt (89H339). 

Although strictly speaking this example does not begin with a preformed ring, the explanation for the conversion of 236 into pyrrolo[3,2-tf pyrimidines 237 by heating with an amine appears to proceed via an unisolated pyrrole (Equation 84) <2000H(53)805>. This process can be explained by cyclization of 236 into 3-dimethylamino-4-(2-pyridinyl)pyrrole-2-carboxylate followed by reaction with another molecule of 236 in which the dimethylamino group is substituted by the aminopyrrole derivative. 

Note This process can be done directly with hydrosulfide ion or indirectly (via an unisolated thiouronium intermediate) using thicurea. 

Concentration Determination of In-Process Samples. The concentration of the unisolated desired product in solution at a particular intermediate step may also need to be determined by HPLC. A data calculation sheet such as Excel with the response factors of the standards and the dilution factor of the sample could be incorporated in the data calculation sheet prior to injection of reaction sample to facilitate the results reporting for the concentration of the intermediate in solution. Hence, only the area of the desired intermediate in solution needs to be populated in the spreadsheet, and the concentration result then can be determined. The determined concentration of the intermediate in solution ensures adequate charging of the raw materials used in the further steps of the synthesis. Also, this intermediate in solution is sometimes further concentrated and the concentration is monitored until the desired concentration is obtained. A solvent switch step is sometimes performed, and the HPLC method must be able to selectively separate the reaction solvents (if they are UV active) from the desired intermediate and potential impurities that may be formed. These reaction solvents may include toluene, inhibited THF with cresol or BHT (if inhibited with BFIT, this is very hydrophobic, so proper elution of this additive may be necessary), ethyl acetate, and so on. Sample preparation here is also important, and the appropriate diluent must be determined to ensure solubility of all components and no reactivity with the sample analyte. 

The photochemistry of this series of benzyl/allyl systems 34 was studied by chemically induced dynamic nuclear polarization (CIDNP) experiments [31]. Contrary to the assertion made here, the authors concluded that the formation of the (unisolated) sulfme 35 was an electrocyclic process, under either direct or sensitized irradiation, because no CIDNP signals were observed. On the other hand, CIDNP results for the acyclic 38 suggest that homolytic cleavage occurs on either side of the sulfoxide. Products were not identified. 

Fig. 11.8. Unisol sweetening process (107). Simplified flowsheet. Courtesy, Oil and Gas Journal.)...

In larger lesions, the array is withdrawn and redeployed anteriorly at 1.5- to 2.0-cm intervals into the tumor. After the hooks are fully deployed, the electrode is connected to the RF generator. The heating protocol for all the available needles is provided by the manufacturer. In general, the generator is started at a lower power setting and is subsequently increased in 10-W increments at 1-min intervals. The endpoint of RF application is the appearance of a rapid increase in tissue impedance (Roll-off) around the electrode. When this occurs, the RF application is automatically terminated. This process is repeated starting at 70% of the roll-off power until a second increase of the impedance occurs. Since the time point of the rapid increase in tissue impedance cannot be predicted, the ablation time needed varies dramatically between different tumor sizes and nodules. At the end of the procedure the needle track is ablated to prevent any tumor dissemination. Therefore, the tip has to be unisolated prior to the insertion of the needle. 

D.. L. Yabroff et al. developed tiie Solutizer process, which permits more complete removal of mercaptans by a caustic solution. An organic, agent is used to. increase the solubility of mercaptans in the caustic solution. The low-molecular-weight mercaptans are dissolved by caustic sdone, but solutizers must be added in order to remove the mercaptans having three or more carbon atoms to the molecule. The Unisol or... 

Uses Defoamer, processing aid for cosmetics Unisol WL [Crodainc]... 

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