Methyl orange, structure

Aniline and other aromatic amines are valuable industrial raw materials. They form an important starting point from which many of our dyestuffs, medicinals, and other valuable products are prepared. For example, you have used the indicator, methyl orange, in your laboratory experiments. Methyl orange is an example of an anQine-derived dye, although it is used more as an acid-base indicator than for dyeing fabrics. The structure of methyl orange is as follows ... 

Schiesser and Lapidus (S3), in later studies, measured the liquid residencetime distribution for a column of 4-in. diameter and 4-ft height packed with spherical particles of varying porosity and nominal diameters of in. and in. The liquid medium was water, and as tracers sodium chloride or methyl orange were employed. The specific purposes of this study were to determine radial variations in liquid flow rate and to demonstrate how pore diffusivity and pore structure may be estimated and characterized on the basis of tracer experiments. Significant radial variations in flow rate were observed methods are discussed for separating the hydrodynamic and diffusional contributions to the residence-time curves. 

C36H60O30,C6H5O3S -Na+-10 H20 Cyclomaltohexaose - sodium ben-zenesulfonate, decahydrate (CDXBZS)275 P212121 Z = 2 D = 1.47 R = 0.07 for 2,894 intensities. This is a channel-type structure, with a conformation very similar to that of the potassium acetate280 and Methyl Orange complexes.281 All of the pyranose residues have the 4Cl conformation, and the primary alcohol groups are in the gauche-trans orientation. 

Table 5.1 summarizes the details of some useful acid-base indicators. Exact agreement with the pH range expressed by equation (5.5) is by no means always observed. This is because some colour changes are easier to see than others and so the general approximation made in deriving equation (5.5) is not uniformly close. Structurally, the indicators form three groups phthaleins (e g. phenolphthalein) sulphonephthaleins (e.g. phenol red) and azo compounds (e.g. methyl orange). 

Some modifications to the cyclodextrin structure have also been found to improve their complexing ability. Casu and coworkers prepared 2,3,6-tri-O-methyl and 2,6-di-O-methyl derivatives of alpha and beta cyclodextrin. They observed that tri-O-methyl-alpha cyclodextrin shows an almost ten-fold increased stability of the complex with the guest, Methyl Orange, compared with the unmodified alpha cyclodextrin. A possible reason for this increase in stability is that the methyl groups are responsible for an extension of the hydrophobic cavity of the cyclodextrin. Other workers,however, observed a much smaller enhancement of stability of complexes on methylation of the cyclodextrin, and a decrease in stability has even been reportedfor the one host-two guests complex of tropaeolin with beta cyclodextrin. Thus, the effect of methylation on the stability of a complex varies with the guest species involved, and cannot be readily predicted. 

It is well known that the aqueous phase behavior of surfactants is influenced by, for example, the presence of short-chain alcohols [66,78]. These co-surfactants increase the effective value of the packing parameter [67,79] due to a decrease in the area per head group and therefore favor the formation of structures with a lower curvature. It was found that organic dyes such as thymol blue, dimidiiunbromide and methyl orange that are not soluble in pure supercritical CO2, could be conveniently solubihzed in AOT water-in-C02 reverse microemulsions with 2,2,3,3,4,4,5,5-octafluoro-l-pentanol as a co-surfactant [80]. In a recent report [81] the solubilization capacity of water in a Tx-lOO/cyclohexane/water system was foimd to be influenced by the compressed gases, which worked as a co-surfactant. 

As further evidence of the importance of hydrophobic interactions in these systems, we examined the partition coefficient of methyl orange in the presence of water structure-forming and water structure-breaking salts above and below the transition temperature [70], Methyl orange is an easily detected, hydro-phobic dye which has been sulfonated to improve water solubility. Water structure-breaking salts like tetraethylammonium chloride (TEAC) are known to minimize hydrophobic interactions while water structure-forming salts like ammonium sulfate are known to increase hydrophobic interactions [165, 166]. 

Equilibrium dialysis studies indicate around 10 repeat VP units (base moles) are required to form favorable complexes. This figure can rise to several hundred for methyl orange and other anions depending on structure. 

The first experimental application of this concept was reported in the seminal work of Dickey, who, in 1949, stated that silica, adsorbed with methyl orange, showed preferential absorption properties towards the same structure. Dickey, hypothesising the mechanism with which the specific adsorption was generated, invoked Pauling s antibody formation theory This mechanism is the same as that proposed by Pauling for the formation of antibodies with use of antigen molecules as a template. [4],... 

Compare the solubility in water of Orange II and Methyl Orange and account for the difference in terms of structure. Treat the first solution with alkali and note the change in shade due to salt formation to the other solution alternately add acid and alkali. 

The structural changes in methyl orange may be represented by the following equations ... 

Methyl red (pH range 4.4-6.2) is an azo compound, the structure of which differs from methyl orange (Orange 3) one by the substitution of sulphonic acid function by carboxylic acid function (Fig. 19). 

S.S) is not unifonnly close. Structurally, the indicators form three groups phthaleins (e.g. phenolphthalein) sulphonephthaleins (e.g. phenol red) azo compounds (e.g. methyl orange). 

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