Titration benzene from

Ethyl bis-(2,4-dinitrophenyl) acetate (indicator) the stock solution is prepared by saturating a solution containing equal volumes of alcohol and acetone with the indicator pH range colorless 7.4-9.1 deep blue. This compound is available commercially. The preparation of this compound is described by Fehnel and Amstutz, Ind. Eng. Chem., Anal. Ed. 16 53 (1944), and by von Richter, Ber. 21 2470 (1888), who recommended it for the titration of orange- and red-colored solutions or dark oils in which the endpoint of phenol-phthalein is not easily visible. The indicator is an orange solid which after crystallization from benzene gives pale yellow crystals melting at 150-153.5°C, uncorrected. 

Ethereal methyl1ithiurn (as the lithium bromide complex) was obtained by the submitters from Aldrich Chemical Company Inc. The checkers used 1.19 M methyl1ithiurn-lithium bromide complex in ether supplied by Alfa Products, Morton/Thiokol, Inc. The concentration of the methyllithium was determined by titration with 1.0 M tert-butyl alcohol in benzene using 1,10-phenanthroline as indicator. The submitters report that ethereal methyllithium of low halide content purchased from Alfa Products, Morton/Thiokol, Inc., gave similar results. 

From eqns. 4.50 and 4.51 it can be seen that complex 1 is converted into complex 2 by a stronger base 2 or into complex 3 by a stronger acid 2 in other words, complexes 2 and 3 are much more stable than complex 1. Whereas reactions 4.48 and 4.49 are addition reactions, reactions 4.50 and 4.51 are exchange reactions often Lewis titrations must be carried out in completely inert solvents such as alkanes or benzene because of instability of the titrants and titrands in other media. Examples of potentiometric Lewis titration curves are given in Fig. 4.9 for CS2 and C0220, where one of their resonance structures can react as a Lewis acid with OH as a Lewis base ... 

Polyurethane networks were prepared from polyoxypropylene (POP) triols(Union Carbide Niax Polyols) after removal of water by azeotropic distillation with benzene. For Niax LHT 240, the number-average molecular weight determined by VPO was 710 and the number-average functionality fn, calculated from Mjj and the content of OH groupSj determined by using excess phenyl isocyanate and titration of unreacted phenyl isocyanate with dibutylamine, was 2.78 the content of residual water was 0.02 wt.-%. For the Niax LG-56, 1 =2630, fn=2.78, and the content of H2O was 0.02wt.-%. The triols were reacted with recrystallized 4,4"-diphenylmethane diisocyanate in the presence of 0.002 wt.-% dibutyltin dilaurate under exclusion of moisture at 80 C for 7 days. The molar ratio r0H = [OH]/ [NCO] varied between 1.0 and 1.8. For dry samples, the stress-strain dependences were measured at 60 C in nitrogen atmosphere. The relaxation was sufficiently fast and no extrapolation to infinite time was necessary. 

Styrene, benzene, and tetrahydrofuran were purified as described previously (8,11). Solutions of ec-butyllithium (Lithium Corporation of America, 12.0 wt % in cyclohexane) and methyllithium (Alfa, 1.45 M in ether) and lithium naphthalene were analyzed using the double titration procedure with 1,2-dibromoethane (12). Lithium naphthalene was prepared in tetrahydrofuran from lithium metal and a 25 mole % excess of sublimed naphthalene at -25°C using standard high vacuum procedures. Sealed ampoules of lithium naphthalene were stored in liquid nitrogen. 

Concerning the nature of the acid sites on dehydrated alumina, the chemical evidence is more in favor of Lewis-type than of Bronsted-type acids. Trambouze and Perrin (343) estimated the content of Lewis acid sites by thermometric titration of a slurry in benzene with dioxane. The authors stated that Lew is acidity was not observed in boehmite and its dehydration products, only in the products obtained from hydrargillite. As mentioned earlier, Webb (339) found no indication of Bronsted acidity ammonia did not form ammonium salts. The quantity of ammonia chemisoi-bed per unit area in the range from 175° to 500° was not a function of the hydrogen content. After exten.sive dehydration, more ammonia was chemisorbed at 100 mm pressure, even at 500°, than corresponded to the hydrogen present (341b). 

Ethereal phenyllithium, prepared from lithium and bromo-benzene,3 may be standardized by adding an aliquot to water and titrating with standard sulfuric acid. 

Diphenylbenzo[c]furan is reportedly attacked by oxygen without catalysts in the dark, even in the solid state. When a solution of 138 in benzene (or toluene) is treated with oxygen, on precipitation with ether a white powder with mp 140°C is obtained in 82% yield on heating to 150— 170°C explosion occurs/ lodometric titration in tetrahydrofuran showed a content of 94% peroxide from this solution 37% o-dibenzoylbenzene (140) has been obtained. The molecular weight was determined to be 2830 (cryoscopic in benzene) and th6 structure formulated as 241 ( = 8-10). 

V) Acidity shall not exceed 0.006% acid calcd as AcOH. A 20g sample dissolved in 100ml of benzene is extracted with three successive 25ml portions of boiled w and the comhined extract titrated with 0.02N NaOH soln using phpht as indicator. A blank detn is run concurrently and % AcOH is calcd from the formula [6.0(V,-VZ)N] /W, where V,=ml of NaOH soln required to titrate sample Vz=ml of NaOH soln required for blank N=normality of NaOH soln and W=wt of sample... 

By use of benzene sulphonic acid or phosphoric acid. When the ester yields on hydrolysis products which become coloured in presence of alkali and air, Method 1 is inapplicable. If the acid produced on hydrolysis is volatile in steam, benzene sulphonic or phosphoric acid may be used as hydrolytic agent, and the acid (from the ester) after separation by steam distillation is titrated with standard alkali. (See Estimation of Acetyl Group, p. 479.)... 

Using the normal addition procedure (02 diffusion into a 75/25 benzene/THF solution of poly(styryl)lithium) the 37% dimer fraction analyzed for 19% alkyl radical dimer and 18% macroperoxide after LiAlH4 reduction. The yield of macroperoxide was also confirmed by thermal decomposition experiments in refluxing toluene, followed again by size exclusion chromatography analysis of the dimer fraction. The amount of hydroperoxide could be deduced from the difference between the amounts of total peroxide (determined by iodometric titration) versus the amount of macroperoxide determined by LiAlH4 reduction. 

Figure 3. Values of H0 for alkaline earth metal oxides titrated with benzoic acid in benzene, using nitroaniline indicators. Key a, MgO b, CaO and c, SiO. (Reproduced, with permission, from Ref. 11.

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