Alsoph H. Corwin

Hyperpressure gas chromatography IV. Gas chromatography of etioporphyrin II metal chelates

Abstract The hyperpressure gas chromatography of fifteen etioporphyrin II metal chelates of fourteen different elements has been studied at 145° and 1000–1700 p.s.i., with dichlorodifluoromethane as the solvent gas. The chelates of Sn(IV) and Mn(III) are insoluble under the experimental conditions and they are, thus, sharply separated from the other elements studied. A column of 10% Epon 1001 resin on Chromosorb W effected the following separations: Mg(II), Cu(II) or Co(II), Ni(II) or Co(III), VO or TiO, Mn(II), Zn or Pt(II) and Pd(II); Ag(II) Pt(II) and Pd(II). A 10% Silicone Gum Rubber XE-60 on Chromosorb W column separated Mn(II) or Fe(III), Zn or TiO, Pt(II) and VO. All the chelates were eluted intact with the exception of that of Mg(II), which was demetallated in the column. A novel method for the insertion of metal ions in the porphyrin ring, involving the reaction of the corresponding metal acetylacetonate with the porphyrin in a suitable solvent, is also reported.

Hyperpressure gas chromatography, III: Gas chromatography of porphyrins and metalloporphyrins

A number of porphyrins and metalloporphyrins have been separated by hyperpressure gas chromatography (HPGC), using dichlorodifluoromethane as the solvent gas and an epoxy resin (Epon 1001) as the selective liquid phase, at pressures up to 3100 psi and temperatures of 140–170°C. The separations effected were: Cu (or Mg), Ni, and vanadyl etioporphyrins II from each other; Sn etioporphyrin II, which is insoluble under the experimental conditions, is sharply separated from the above chelates; etioporphyrin II, mesoporphyrin IX diethyl ester, mesoporphyrin IX dimethyl ester, deuteroporphyrin IX dimethyl ester, and desoxophyllerythrin methyl ester from each other. Etioporphyrin II and desoxophyllerythroetioporphyrin were separated in a Versamid 900 column. Attempts to separate etioporphyrins II and III have failed but slightly different retention characteristics have been observed and the pyrolytically prepared etioporphyrin III could be resolved into the monomeric compound and the byproducts of the reaction. For porphyrins insoluble in CCl2F2, the addition of small amounts of a liquid solvent to the carrier gas is proposed. The above results indicate that hyperpressure gas chromatography is suitable (1) for nonvolatile compounds, which cannot be gas chromatographed by conventional methods, and (2) for the elution of compounds decomposed thermally at the temperatures suitable for their conventional gas chromatography. In conclusion, the first application of hyperpressure gas chromatography showed that the method is a powerful analytical tool for both inorganic and organic chemistry.

The preparation of mesoporphyrin IX and etioporphyrin III

Abstract Under mild alkaline conditions hemin can be catalytically hydrogenated to the iron complex of mesoporphyrin IX. Subsequent demetallation yields mesoporphyrin IX. In this way pure mesoporphyrin IX becomes readily accessible. In contrast, the mesoporphyrin produced from hemin by formic acid reduction has been shown by partition chromatography to be a mixture rather than a pure compound. Mesoporphyrin IX can be converted to pure etioporphyrin III in 20% yield by a seven-step reaction series including the Curtius rearrangement, Hofmann degradation, and catalytic hydrogenation.

Substituent effects in porphyrins and metalloporphyrins

Abstract Substituent effects on complex formation between variously substituted metallodeuteroporphyrins with filled t 20 orbitals and extraplanar ligand(s) can be correlated by Hammett free-energy plots. The slopes of these plots are positive and the correlation is high with substituent constants typical of resonance transmission of electronic effects. Conversely, correlation of the monoprotonation of substituted deuteroporphyrins requires σ m substituent constants, indicative of the inductive mode of transmission. Electron spin resonance spectra of the d 9 metalloporphyrins are in accord with the concept of the resonance mode of transmission and suggest that the porphyrins with strongly electron withdrawing groups produce a relatively low ligand field.

Dyes as biologic probes, color and dye microenvironments

Abstract The color changes of several dyes were studied in the presence of detergent micelles. Changes in the absorption maxima of the dyes and alterations in their equilibrium constants were measured in solvents of varying polarity. Similar effects were measin detergent micelles as a result of the hydrophobic microenvironment experienced by the micelle-bound dye. In addition, microenvironmental electrostatic effects were observed. The latter cause large changes in the equilibrium constants of the dyes as a result of the juxtaposition of charged functional groups in the detergent micelles.

The nature of some protein microenvironmental effects

Abstract Certain dyes respond to environmental polar and electrostatic changes with corresponding alterations in their visible spectra. An interpretation of this phenomenon occurring when these dyes interact with some blood proteins is used to describe polar and electrostatic properties of their binding sites.

Anomalies of viologens in bases and water

The use of viologens as oxidation-reduction indicators in the biochemical field has greatly increased recently. In the presence of organic and inorganic bases the viologens undergo an auto-reduction which casts doubts on their general reliability as oxidation-reduction indicators. The inorganic bases act on the viologens only at high concentrations of the latter; however, some nitrogen bases, like pyrrolidine and piperidine, cause the blue coloration even at the low concentrations used in biochemical work. KOH, NaOH and Na2CO3 (not NaHCO3) gave the characteristic blue coloration of the reduced form when added to aqueous solutions of the viologens. Piperidine, pyrrolidine and pyridine affect the viologens in a similar manner. Benzyl viologen was reacted with NaOH, NaOCH3 and pyrrolidine and the products of each reaction were isolated. On the basis of these results a mechanism is proposed for this disproportionation. Although reduced viologens do not follow Beers law in water, we have found that they do follow it in certain organic solvents. The conclusions show that reductions of both benzyl and methyl viologen carried out at high pH values or in the presence of a nitrogen base may be partially or totally the result of the interaction of the base with the viologen.

COLUMN PARTITION CHROMATOGRAPHY OF PORPHYRINS.

Abstract A number of porphyrins can be resolved by column partition chromatography using dimethyl sulfoxide on a silica support and cyclohexane as the mobile phase. This partition system was used as a criterion of success in the selection of new methods for the synthesis of porphyrins. The important factors which allow quantitative and reproducible evaluations of Rf values are noted, and differences in dielectric constant are recommended as a useful test for selection of other suitable chromatographic solvent pairs.

INDIVIDUAL SUSCEPTIBILITY TO FOOD CONSTITUENTS

Individual hypersusceptibility to chemical substances is a well-known phenomenon in toxicology and pharmacology.’ The role of this phenomenon in pathological reactions to common foods, however, is imperfectly understood. If suitable measuring techniques were available, this field should lend itself to a study of biological variation in humans. Problems arising from individual variations in tolerance for common foods have been recognized since antiquity.’ Progress in understanding and controlling these problems has been painfully slow. A major portion of this difficulty has been due to the fact that man has only a limited number of physiological mechanisms for adaptation to his constantly changing environment so that the same adaptation reactions occur in response to a broad variety of stimuli. It is very difficult to keep a subject isolated from all extraneous stimuli in order to test the effect of a single factor. Another unsolved problem is to determine the boundary between a normal adaptive response and a pathological reaction. Even when abnormal reactions are obvious, it is very difficult to establish a causal relationship with a single factor. This laboratory has been engaged in chemical and physiological studies designed to aid in both understanding and diagnosing pathological responses to foods. Two broad categories of abnormal responses to unspoiled foods have been studied. The earliest group to be classified was that labelled as “allergic.”3 Shortly afterward, responses falling into the category of “inherited metabolic defects”’ were recognized. Disentangling the two categories is difficult in many cases. Indeed, Godlowski5 presents arguments for regarding all allergic responses as due to inherited metabolic defects. While this is a theoretical possibility, it seems wise at the present time to reserve this category for cases in which the enzymatic abnormality causing the pathological response can be identified with precision. Examples have been described by Mountain6 in which hereditary deficiencies in enzyme systems of erythrocytes produce hypersusceptibility to a large number of commonly used chemicals. A comprehensive study of metabolic errors has been prepared under the editorship of Stanbury, Wyngaarden and Fredrickson.’ One method proposed for the diagnosis of food allergy is that of A. F. Coca.s His procedure requires a systematic recording of the pulse acceleration of an individual upon exposure to suspected foods or inhalants. His conclusion that all allergic reactions are accompanied by pulse accelerations amounts to a definition of food and inhalant allergy in terms of pulse response. I t is certainly conceivable, however, that other responses might occur independently of pulse accelerations. Corwin, Hamburger and Dukes-Dobosy have examined Coca’s data and have found that the changes in heart rates of the individuals whom he studied have magnitudes that satisfy the requirements of statistical significance. This suggests an abnormal reactivity of the autonomic nervous systems of these individuals to selected foods and inhalants.