4B acid

Rectified turpentine Rectodelt Rectules Red 169 Red 2B acid Red 2G Base Red 4B acid Red algar Red arsenic glass Red arsenic... 

The sulfonation of 4-toluidine yields 4-aminotoluene-3-sulfonic acid (4B acid). This acid is used in the production of one of the most important red pigments, Pigment Red 57 1. 

Diazotization reacting a primary aromatic amine with nitrous acid that was formed in situ by reacting sodium nitrite with hydrochloric acid this forms a diazonium salt. Some common primary amines are Tobias acid, C acid, 4B acid, 2B acid, and anthraniUc acid. 

Acid-Catalyzed Intermolecular Dehydration of a Primary Alcohol (Section ii.4B) Acid-Catalyzed Addition of an Alcohol to an Alkene (Section 11.4C)... 

Hydrolysis of an Acid Anhydride (Section 18.4B) Acid anhydrides react readily with water. 

Rate constants for the Diels-Alder reaction of 2.4b-e have also been determined. The results are shown in Table 2.3. These data allow an analysis of the influence of substituents on the Lewis-acid catalysed Diels-Alder reaction. This is interesting, since there are indications for a relatively large... 

Pigment Red 57, calcium salt [5281-04-9] 15850 1 BONA (Ca salt) (Lithol Rubine B or 4B toner) coupling of dia2oti2ed 2- amino-5-methyl-ben2enesulfonic acid with 3- hydroxy-2-naphthoic acid, foUowed by salt formation... 

The new approach for development of pH sensor with wide acidity range (2.5 M H SO - pH 5.5) based on the use of Congo Red and Benzopurpurin 4B immobilized in polyamido- or arachidic acid nanosized sensitive matrix will be demonstrated. 

Subtilisin (from Bacillus subtilis) [9014-01-1 ] [EC 3.4.21.62]. Purified by affinity chromatography using 4-(4-aminophenylazo)phenylarsonic acid complex to activated CH-Sepharose 4B. [Chandraskaren and Dhai Anal Biochem 150 141 7955]. 

Scheeren et al. reported the first enantioselective metal-catalyzed 1,3-dipolar cycloaddition reaction of nitrones with alkenes in 1994 [26]. Their approach involved C,N-diphenylnitrone la and ketene acetals 2, in the presence of the amino acid-derived oxazaborolidinones 3 as the catalyst (Scheme 6.8). This type of boron catalyst has been used successfully for asymmetric Diels-Alder reactions [27, 28]. In this reaction the nitrone is activated, according to the inverse electron-demand, for a 1,3-dipolar cycloaddition with the electron-rich alkene. The reaction is thus controlled by the LUMO inone-HOMOaikene interaction. They found that coordination of the nitrone to the boron Lewis acid strongly accelerated the 1,3-dipolar cycloaddition reaction with ketene acetals. The reactions of la with 2a,b, catalyzed by 20 mol% of oxazaborolidinones such as 3a,b were carried out at -78 °C. In some reactions fair enantioselectivities were induced by the catalysts, thus, 4a was obtained with an optical purity of 74% ee, however, in a low yield. The reaction involving 2b gave the C-3, C-4-cis isomer 4b as the only diastereomer of the product with 62% ee. 

In an extension of this work Scheeren et al. studied a series of derivatives of N-to-syl-oxazaborolidinones as catalysts for the 1,3-dipolar cycloaddition reaction of 1 with 2b [29]. The addition of a co-solvent appeared to be of major importance. Catalyst 3b was synthesized from the corresponding amino acid and BH3-THF, hence, THF was present as a co-solvent. In this reaction (-)-4b was obtained with 62% ee. If the catalyst instead was synthesized from the amino acid and... 

A solution of tetrahydropapaverine (4.43 g) and 1,5-pentamethylene diacrylate (1.30 g) in dry benzene (15 ml) was stirred under reflux for 4B hours excluding light. The solvent was removed in vacuo and the residual pale red oil dissolved in chloroform (10 ml). Addition of ether (ca 400 ml), followed by saturated ethereal oxalic acid solution (ca 500 ml) gave a floc-culent white precipitate, which was filtered off, washed with ether and dried. Crystallization (twice) from ethanol gave N,N -4,10<)ioxa-3,11 <)ioxotridecvlene-1,13-bis-tetrahydropapa-verlne dioxalate as a white powder (3.5 g 51% MP 117°to 121°C). 

This product was dissolved in 10 ml of chloroform. To this solution were added 10 ml of a 10% aqueous solution of caustic soda and the mixture was warmed at 50°C to effect hydrolysis of the ester group. After completion of the reaction, the organic phase was separated, washed with water and distilled to remove the solvent whereby 2.1 g (yield 4B%) of the end product, i.e., N-(3, 4 -dimethoxycinnamoyl)-anthranilic acid, were obtained. This product had a melting point of 211°C to 213°C. 

Methyl-2-nitrodibenzo[b,/ thiepin-10-carboxylic Acid (4b) Typical Procedure 60... 

Thus, cyclization of the (Z)-hexenyllactam 3b in formic acid leads to quantitative formation of the equatorial formate (27 )-4b, via a chair-like transition state, with conservation of the... 

A kinetic study of the electrophilic substitution of pyridine-N-oxides has also been carried out50b,c. Rate-acidity dependencies were unfortunately given in graphical form only and the rate parameters (determined mostly over a 30 °C range) are given in Table 4b. There is considerable confusion in Tables 3 and 5 of the original paper, where the rate coefficients are labelled as referring to the free base. In fact the rate coefficients for the first three substituted compounds in... 

D. 2(S)-(fl-tert-Butoxycarbonyl-a-(R)-hydroxyethyl)-4-(R)-hydroxy-pyrrolidine- 1-carboxylic acid, tert-butyl ester. The identical procedure was followed, in this case using the (,S)-BINAP catalyst (5)-l. Hydrogenation is conducted for 64 hr, and the reaction mixture is then transferred to a 250-mL, round-bottomed flask and concentrated to dryness. The residue is dissolved in 17 mL of methanol and cooled to 15°C. After the slow addition of 7 mL of DI water, the solution is aged for 15 min gradually forming a thin slurry. More DI water (75 mL) is added over 1 hr and the mixture is allowed to stand for an additional 1 hr at 15°C. The resulting crystals (Note 19) are filtered at 15°C, washed with 10 mL of 1 4-MeOH water, and then dried overnight in a vacuum oven (35°C, 686 mm) to yield 7.0 g (70%) of (R)-hydroxy ester 4b (Note 20). 

SEI f-Test L.4B The amount of arsenic(IIl) oxide in a mineral can be determined by dissolving the mineral in acid and titrating it with potassium permanganate ... 

Self-Test 11.4B Calculate the ratio of the molarities of benzoate ions and benzoic acid (C6H,COOH) needed to buffer a solution at pH = 3.50. The pKa of C6H,COOH is 4.19. 

Sfi.F-Test 19.4B Write the formula for (a) the monomer of poly(methyl methacrylate), used in contact lenses (17) (b) two repeating units of polyalanine, the polymer of the amino acid alanine, CH,CH(NH2)COOH. 

Fig. 6.4b. Melasma before and after a series of five salicylic acid peels and 4% hydroquinone...

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