Methyl anthraquinone, effect

The effect of temperature, and of temperature and pH on the retention of a selected group of compounds using a beta-cyclodextrin column was studied. The results indicated that a plot of Ink vs. 1/T gave linear relationships for anthraquinone, methyl anthraquinone, ethyl anthraquinone, naphthalene and biphenyl using a mobile phase of methanol/water. However, a non linear relationship was observed for a selected group of dipeptides employing a mobile phase of methanol/ammonium acetate at the following pH s 1, 5.5 and 7. The retention times decreased with an increase in the temperature of the column except that for certain dipeptides the retention times increased. The separation factor (a) values decreased by approximately 10 with increase in column temperature from 25°C to 77°C. 

EFFECT OF METHANOL IN THE ELUENT ON RETENTION. The effect of increasing the volume of the organic modifier, methanol, in the mobile phase on the retention of methyl anthraquinone and naphthalene is given in Figure i(. Methyl anthraquinone and napthalene are more soluble in methanol than in water so increasing the volume of methanol in the mobile phase should result in the increase in the solubility of both compounds, and as a result, a decrease in the retention time. Also, the presence of methanol in the mobile phase affects retention when cyclodextrin bonded columns are used. Methanol is much more tightly bound in the cyclodextrin cavity than... 

Figure Effect of volume of methanol in the eluent on the retention times of methyl anthraquinone (-0-) and naphthalene (-0-) using a B-cyclodextrin column, 4,6 x 100 mm, and a flow rate of 1 ml/min.

The condensation of toluene with phthalic anhydride takes place in the presence f aluminum chloride even at room temperature and is complete after about 12 to 15 hours of stirring. The ring closure can be effected with 5 per cent oleum (10 parts for 1 part of toluylbenzoic acid) by heating on a water bath for 2 hours. Usually, however, the preparation is done exactly as described for the preparation of anthra-quinone from phthalic anhydride and benzene. The yield of 2-methyl-anthraquinone, melting at 170-174°C., is about 85 to 88 per cent of the theoretical amount calculated on the phthalic anhydride. 

The use of potassium bichromate in sulfuric acid effects the oxidation of l-nitro-2-methyl-anthraquinone to the corresponding carboxylic acid. This reaction illustrates side-chain oxidation, an important route to carboxylic acids. 

This derivative is prepared from an A-protected amino acid and the anthryl-methyl alcohol in the presence of DCC/hydroxybenzotriazole. It can also be prepared from 2-(bromomethyl)-9,10-anthraquinone (Cs2C03). It is stable to moderately acidic conditions (e.g., CF3COOH, 20°, 1 h HBr/HOAc, t,/, = 65 h HCI/CH2CI2, 20°, 1 h) Cleavage is effected by reduction of the quinone to the hydroquinone i in the latter, electron release from the -OH group of the hydro-quinone results in facile cleavage of the methylene-carboxylate bond. 

In a related series of 1,2,4-trisubstituted anthraquinone compounds, the effectiveness of various polar and nonpolar substituents to improve on the low heat fastness of 2-amino-1,4-dihydroxyanthraquinone (3.184 R = H) was examined (Table 3.50). Short-chain alkyl groups (methyl, ethyl) and even the pyranylmethyl ether are relatively ineffective but hydroxyalkyl, cyclohexyl, benzyl and morpholinylethyl groups show moderate increases. Further improvement is given by phenyl, pyridylmethyl and morpholinylpropyl. Outstandingly effective, however, are the benzothiazolyl, dodecylphenyl and fluoro-methylphenyl groupings. 

The effect of change in column temperature on the retention of anthraquinone, methyl- and ethylanthraquinones between 25°C and 55°C was a decrease of 75, 76 and 77 respectively. 

Technical Observations. A whole series of altyl and phenyl ethers in the benzene series (also in the naphthalene and anthraquinone series) can be prepared in an analogous manner. While anhydrous methylate gives satisfactory results in the case of nitroanisole, there are other cases (e.g., dinitroanisole from dinitrochloro-benzene) where it is betSr to use caustic potash, the small water content having no deleterious efFect. Moreover, better reswts are often obtained if onb 90 per cent of the calculated quantity of alkali is used. 

Emodin (l,6,8-trihydroxy-3-methylanthraquinone), the active principle of Polygonum cuspidatum (Polygonaceae), was reported to be an inhibitor of the p56 -PTK activity from bovine thymus, with an IC50 of 18.5 pM. When the hydroxyl functions at C-6 or C-8 were blocked by methylation or glycosylation, respectively, the effect disappeared. The inhibition was competitive with respect to ATP and non competitive with respect to the substrate [64]. In a bioassay-guided separation of the anthraquinones found in rhizomes of another Polygonaceae species, rhubarb Rheum... 

Figure 30-19 Effect of solvent variation on chromatograms. Analytes (1) 9,10-anthraquinone (2) 2-methyl-9,10-anthraquinone (3) 2-ethyl-9,10-anthraquinone (4) l,4-dimethyl-9,10-anthraquinone (5) 2-t-butyl-9.10-anthraquinone.

Polymer effects on the photoactivity of the thioxanthone chromophore have also been found to be negligible whereas in the anthraquinone induced photopolymerisation of methyl methacrylate the polarity of the solvent was found to markedly influence the rate of polymerisation . In this case the rate was directly proportional to the solvent polarity whereas the molecular weights were found to be inversely related. 

Flett [32] has found similar effects with amino-anthraquinones and he has shown that in these structures hydrogen bonding can play only a small part, even with unsubstituted amines. Thus the NH stretching frequency of 1-amino-anthraquinone is not very different from that of 2-naphthylamine, and the NH frequency of 1-methyl-amino-anthraquinone is only 100 cm" lower than is usual for secondary amines. This contrasts sharply with the behaviour of the corresponding hydroxy-compounds, in which no OH stretching frequencies are shown in the normal frequency range. Furthermore, Flett finds that 2-amino-anthraquinones show nearly as much movement of the carbonyl absorption as the 1-amino-materials, and... 

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