Chlorobenzene determination

Hollingsworth R.L., Rowe V.K., Oyen F., Hoyle H.R., Spencer H.C. (1956) Toxicity of paradi-chlorobenzene determinations on experimental animals and human subjects. AMA Archives of Industrial Health 14 138-147. 

For an actual determination, first place in J some stable liquid the boiling-point of which is at least 50 above that of the organic liquid the pour density of which is to be measured. This difference in boiling-point is important, because it is essential that the organic liquid, when nbsequently dropped into the bottom of T, should volatilise rapidly nd so push out an equivalent volume of air before the organic vapour can diffuse up the tube T and possibly condense in the cooler ttppcr portion of the tube. Suitable liquids for use in the jacket are ter, chlorobenzene (132°), rym-tetrachloro-ethane (147 ), P ... 

Repeat the boiling point determination with the following pure liquids (a) carbon tetrachloride, A.R. (77°) (6) ethylene dibromide (132°) or chlorobenzene (132°) (c) aniline, A.R. (184-6°) and (d) nitrobenzene, A.R. (211°). An air condenser should be used for (c) and (d). Correct the observed boiling points for any appreciable deviation from the normal pressure of 760 mm. Compare the observed boiling points with the values given in parentheses and construct a calibration curve for the thermometer. Compare the latter with the curve obtained from melting point determinations (Section 111,1). 

Characteristics of the system as nitrating reagents Wibaut, who introduced the competitive method for determining reactivities (his experiments with toluene, benzene and chlorobenzene were performed under heterogeneous conditions and were not successful), pointed out that solutions of nitric acid in acetic anhydride are useful in making comparisons of reactivities because aromatic compounds are soluble in them. ... 

Titrations with dibutylamine [111-92-2] can also be used to determine the NCO content of isocyanates and prepolymers. Generally, an excess of amine in a suitable solvent such as chlorobenzene [108-90-7] is added to the sample. The resulting solution is allowed to react and the unreacted amine is back- titrated with dilute hydrochloric acid. For low NCO content levels, a colorimetric method is often used. The isocyanate-containing species is titrated with amine and the unreacted amine is deterrnined using malachite green [569-64-2]. 

The first detailed investigation of the reaction kinetics was reported in 1984 (68). The reaction of bis(pentachlorophenyl) oxalate [1173-75-7] (PCPO) and hydrogen peroxide cataly2ed by sodium saUcylate in chlorobenzene produced chemiluminescence from diphenylamine (DPA) as a simple time—intensity profile from which a chemiluminescence decay rate constant could be determined. These studies demonstrated a first-order dependence for both PCPO and hydrogen peroxide and a zero-order dependence on the fluorescer in accord with an earher study (9). Furthermore, the chemiluminescence quantum efficiencies Qc) are dependent on the ease of oxidation of the fluorescer, an unstable, short-hved intermediate (r = 0.5 /is) serves as the chemical activator, and such a short-hved species "is not consistent with attempts to identify a relatively stable dioxetane as the intermediate" (68). 

The enthalpy of the adsorption of chlorobenzene was determined from the temperature-dependence of the SERS intensities [4.301]. 

Park and Smith 170 attempted to allow for chain transfer in their examination of the termination mechanism during VC polymerization at 30 and 40 °C in chlorobenzene. They determined the initiator-derived ends in PVC prepared with radiolabeled AIBN and concluded that kjk = 3.0. However, questions have been raised regarding the reliability of these measurements.171 172 Atkinson et al.x72 applied the gelation technique (Section 5.2.2.2) to VC polymerization and proposed that termination involves predominantly combination. 

Third-order rate coefficients were determined for reaction of some aromatics with 3,4-dichlorobenzyl chloride at 25 °C as follows chlorobenzene, 0.745 x 10 3 benzene, 1.58 x 10-3 toluene 2.60 x 10—3 m-xylene, 3.30 x 10-3 and these show the unselective nature of the reaction. With 4-nitrobenzyl chloride, benzene gives a third-order rate coefficient of 4.78 x 10 6, which diminishes to 2.4 and 1.9 x 10-6 as the benzene composition of the solvent was increased to 50 and 83 vol. %, respectively. 

Chlorobenzenes, sulphur-containing, reactivities of 590, 591 Chloropalladiosulphonylation 172 Chromanones, synthesis of 328 Chromatographic methods for detection and determination 111-113, 119-121... 

Mandal and Hay28 used MALDI-TOF mass spectrometry to determine the absolute molecular masses and endgroups of 4-phenylphenol novolac resins prepared in xylene or chlorobenzene. Peaks with a mass difference of 44 (the molecular weight of a xylene endgroup) suggested that reactions conducted in xylene included some incorporation of xylene onto the chain ends when a strong acid such as sulfuric acid was used to catalyze the reaction. By contrast, no xylene was reacted into the chain when a milder acid catalyst such as oxalic acid was used. No chlorobenzene was incorporated regardless of the catalyst used. 

Protonation of the TMM complexes with [PhNMe2H][B(C6Fs)4] in chlorobenzene at —10 °C provided cationic methallyl complexes which are thermally robust in solution at elevated temperatures as determined by NMR spectroscopy. In contrast, addition of BfCgFsls to the neutral TMM precursors provided zwitterionic allyl complexes (Scheme 98). Surprisingly, it was found that neither the cationic nor the zwitterionic complexes are active initiators for the Ziegler-Natta polymerization of ethylene and a-olefins. °°... 

A recent stndy (13,27) describes the use of Co-Si-TUD-1 for the liquid-phase oxidation of cyclohexane. Several other metals were tested as well. TBHP (tert-butyl hydroperoxide) was used as an oxidant and the reactions were carried out at 70°C. Oxidation of cyclohexane was carried out using 20 ml of a mixture of cyclohexane, 35mol% TBHP and 1 g of chlorobenzene as internal standard, in combination with the catalyst (0.1 mmol of active metal pretreated overnight at 180°C). Identification of the products was carried out using GC-MS. The concentration of carboxylic side products was determined by GC analysis from separate samples after conversion into the respective methyl esters. Evolution and consumption of molecular oxygen was monitored volumetrically with an attached gas burette. All mass balances were 92% or better. 

The research department has developed a new process for producing chlorobenzene and wants to pursue it further. The company has never produced chlorobenzene, but feels that if the price is right it would be willing to build a plant for its production. Before doing this, not only must it estimate what the proposed plant will cost but it must determine what costs the current manufacturers have. The proposed process will be dropped unless it has an economic advantage over the present process. 

Su,Y., Lei, D.L. Daly, G.,Wania, F. (2002) Determination of octanol-air partition coefficient (KqA) values for chlorobenzenes and polychlorinated naphthalenes from gas chromatographic retention times. J. Chem. Eng. Data, 47, 449 455. 

The purity of the product can be determined 3 6 by titration in glacial acetic acid, using perchloric acid (in glacial acetic acid) as titrant and methyl violet (0.2 g. of methyl violet in 100 ml. of chlorobenzene) as visual indicator (the first appearance of blue color is taken as the end point). 

The following compounds were determined by this procedure chloroform bromoform 1,1,1-trichloroethane 1,1,2,2-tetrachloroethane trichloroethylene benzene carbon tetrachloride toluene bromodichloromethane chlorobenzene 1,1,2-trichloroethane o,p-xylene tetrachloroethylene o,p-chlorotoluene 1,2-dibromoethane and fluorobenzene (used as an internal standard). 

Kester [5] has discussed the application of the purge and trap gas chromatographic method discussed in section 5.1.1.3 to the determination of chloroaromatic compounds such as chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, bromobenzene in soils. Following methanol extraction of the soil the extract is gas purged and the purge gases trapped on a Tenax 1 silica gel-charcoal trap followed by thermal desorption from the trap and examination by gas chromatography and/or mass spectrometry. 

The isooctane extraction gas chromatographic procedure [14] described in section 5.2.2.1 has been applied to the determination of various (0.003-0.07mg kg-1) chlorobenzenes in estuarine sediments. 

A similar technique was used almost simultaneously by Penczek [18, 19] for the polymerisation of bis-chloromethyl oxetan (BCMO) by (i-Bu)3A/-H20 in chlorobenzene. In this system, too, there is termination by reaction of growing centres with polymer, but initiation is slow and the equations are correspondingly more complicated. The authors believe that their value of the propagation rate-constant refers to ion-pairs and is thus k"v, and we see no reason to disagree with their view they also determined k and kt. 

Forlani and coworkers184 determined that the magnitude of k was found to increase linearly with nucleophile concentration for the reaction of picryl fluoride with 2-hydroxypyridine in chlorobenzene, and k E/k D = 1.5 for mono-deutero-2-hydroxypiridine was observed184. Since isotope effects are usually small in S/yAr in apolar solvents1 the authors attributed the isotope effect to the formation of a substrate-catalyst molecular complex. They obtained a value of k E/kp, D = 1-75 for the ratio of the association constants, hAd- When the substrate was picryl chloride, the slight increase of k with nucleophile concentration was interpreted in terms of Scheme 6 giving a value of K = 2.9 1 identical with that for the fluoro-substrate (3.0 1). 

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