Chromic comparison with

The UV-spectrum of lunacridine, which is unchanged in acid or alkali, is consistent with the presence of a 2-quinolone system the batho-chromic shift of the maxima at 284 and 294 m/x, in comparison with those of 4-methoxy-l-methyl-2-quinolone (268 and 278 m/a), can be attributed... 

The presence of a 1,2-methylenedioxy group results in a batho-chromic shift of the 235-256 nm band by comparison with the spectrum of the corresponding 1,2-dimethoxy analog. To cite one example, liriodenine (1) has a peak at 247.5 nm but lysicamine (2) shows an absorption maximum at 235 nm. 

Glycosmicine was obtained by potassium permanganate, periodic acid (72), or chromic acid (75) oxidation of arborine (1). This fact and the spectral data indicate structure 4 for this alkaloid, which was confirmed by comparison with synthetic material prepared from 7V-methylanthranilamide and ethyl chloroformate. 

Some conjugated polymers and liquid crystalline polymers which possess thermo-chromic properties are promising electrochromic materials. In comparison with the... 

Furthermore, Sato and Ikekawa (238) have obtained by chromic acid oxidation of (257 )-22,26-acetylepimino-3/3,16(8-diacetoxycholesta-5,22-diene (LX), prepared from solasodine (I) by acetylation (238, 239), 16 -hydroxy-3(8-acetoxy-22,23-bisnorchol-5-enic lactone (acetyldios-genin lactone, LXI). The side chain fragment of this degradation, which involves the carbon atoms 23-27 including the center of chirality C-26, has been identified as (R)-( — )-4-amino-3-methylbutyric acid (LXII) (240), the constitution of which was confirmed by comparison with the synthesized racemic compound. Its absolute configuration was confirmed by conversion into (R)-( +)-methylsuccinic acid (LXIII) (225, 226). 

The ability to probe surfaces using in situ SERS can be exploited in polymer chemistry to characterise the surface of polymers for comparison with the bulk properties and to study polymer-metal composites such as adhesives and coatings. Interactions between adhesives and metal polymeric surfaces have been investigated [437]. The applicability of SERS to polymer surfaces has also been reported in a study on poly-/ -nitrostyrene [438], and in another study on the effects of chromic/sulfuric acid etching on PE films [439]. The desired surface sensitivity... 

In the present work, steel surfaces polished, phosphated and painted are studied using AC Impedance technique In order to evaluate the protection efficiency of a commercial phosphatlng solution. The AC Impedance behavior of painted metal has been correlated with the Immersion time In the phosphatlng solution and with the desirability of a phospho-chromic rinse (18-23). A comparison of the Impedance behavior of two different types of commercial paints Is made for various durations of Immersion In sodium chloride solution at room temperature, and also for various temperatures at a given duration of Immersion. 

Chromic Oxide. This appears to be a p-type semiconductor in oxygen but becomes n-type when heated in hydrogen (Weller and Voltz, 144o)- A comparison of its catalytic properties with those of zinc oxide (n-type) is therefore of some interest. 

Comparison of the electrical conductivities of chromium penta-phenyl hydroxide, sodium hydroxide and ammonia in absolute methyl alcohol and in methyl alcohol-water solution, shows that the former is a very strong base. In aqueous methyl alcohol solution the chromium compound does not appear to approach the limiting value with increasing dilution. The ultra-violet absorption spectrum examined in absolute ethyl alcohol solution resembles that of chromic acid and the dichromates, but the absorption is noticeably greater in the case of the organic compound. 

In addition, the toluene must be practically free from olefines or members of the di-olefine series. This demands that the toluene be washed several times with concentrated sulphmic acid to remove these compounds. The laboratory test for olefines consists in agitating some of the toluene with a certain percentage of concentrated sulphuric acid. If olefines are present, the acid layer will acquire a yellow to red color. This color must not be deeper than whatever shade the certain plant has adopted as its standard. The comparison standard colors consist of definite concentrations of solutions of potassium dichromate, chromic acid, etc. 

The identity of the ketone (179) could not be confirmed by direct comparison owing to the non-availability of an authentic specimen of the ketone (179). In order to confirm the identity of the ketone (179), its carbonyl group was eliminated by Clemmensen reduction [75]. The resulting deoxygenated material without purification was subjected to oxidation with chromic acid in acetic acid and demethoxylation with silicon... 

The effect will be clear from a comparison of the magnetic properties of chromium oxide gel with those of massive crystalline chromic oxide. Chromium oxide gel may be made by precipitation of the hydroxide from a nitrate solution, followed by slow dehydration. Several other processes are available, of which slow reduction from a basic chromate solution is one. On ignition, these gels generally undergo the glow-phenomenon during which they revert to Crystalline chromic oxide. 

Table II shows the magnetic susceptibility of a chromium oxide gel compared with that of crystalline chromic oxide. The gels always contain some water, hence a more striking comparison is made by calculating the susceptibility of the chromium ions in each substance.

The stone appeared black, was rounded, with no evidence of a solution sac, as shown in Figure 5(a). The petrographic analysis revealed a solid inner core with a crystalline perimeter (Figure 5(b)). Neither, the inner core of the stone nor the crystal plates at the perimeter could be identified through the analysis methods of crystal morphology. However, based on the physical appearance of the stone when viewed in cross-section, a comparison to the literature identified this type of stone as typical of an iron chromite inner core and perimeter crystals of chromic oxide. 

By way of comparison it may be pointed out that camphene (4) with chromic acid in aqueous acid gives, as the chief product, camphor (135) and not camphenilanic acid (136), apparently due to fast prior hydration of camphene to isoborneol (83, R = H) (85). This reaction has not been observed with longifolene. Low conversions of camphene to the acid (136) can be, however, achieved by carrying out this oxidation in acetic anhydride-carbon tetrachloride (87), and under these conditions camphene epoxide has been demonstrated (88) as the primary oxidation product. 

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