Synthese von Chlorinen

Abstract

Fiischer tind H e l b e r g e r , Synthese von Chloiinen. 286 a d 5 Minuten abgekiirzt wurde. Die Aufarbeitung wurde, urn rasch zum Ziel zu kommen, uber .hher-Salzs&ure vorgenommen. Das Porphyrin wurde nach dem Abdampfen des Athers sofort mit methylakoholischer Salzsiiure verestert. Der Esterschmelz-und Miechschmelzpunkt lag bei 231O (korr.). Spektroskopisch bestand auch Identiat mit Protoporphyrin. Die Ausbeute entsprach einer normalen Darstellung. Mesoporphyrin wurde in iiblicher Weise durch Reduktion mit Jodwaeaerstoff-Eisessig dargestellt. Die Aufarbeitung geschah auch iiber Ather-Salzsiiure. Der Esterschmelz-und Mischschmelzpunkt lag bei 2110 (korr.). Auch spektroskopisch war volle ubereinstimmung vorhanden, die Ausbeute war normal. Ganz ebenso wurde mit Hiimin-acetat verfahren, das bei 150° getrocknet worden war. Die Versuche verliefen ebenso, doch waren in beiden Fa.llen die Ausbeuten etwas schlechter. Der Schmelzpunkt des Protoporphyrinestem lag bei 228O (korr.) der Mischschmelzpunkt mit dem Vergleichspriiparat bei 231O. Der Schmelzpunkt des Mesoporphyrinesters war 208O, der Mischschmelzp. 21.0°. Auch die spektroskopische Identitiit war vorhanden.

Chlorophyll.

“…Now phylloerythrin is a porphyrin (22), on the grounds of its spectroscopic behavior. Thus for the first time a basis was obtained for the view that the chlorophyll molecule also stood in close relation to the porphyrins; a possibility further supported by synthetic studies through conversion of blood pigment porphyrins into chlorins and rhodins (55,17,12). By bacteriological methods (19,20) chlorophyll derivatives were likewise converted into porphyrins, again a confirmation of the relations stated above.…”

“…Consequently isomerism among the porphyrins, the phorbides and the chlorins could not be a correct explanation and contradictions appeared on every side. The possibility of methylene groups as bridges between the pyrrole nuclei or of pyrroline formation (17,12) was brought into discussion. The latter explanation, which was primarily applied to the synthetic chlorins, was difficult to apply to the "natural" products, since according to the state of knowledge at that time, a higher hydrogen content must occur in the latter molecules than in the porphyrins.…”

The Synthesis, Properties, and Reactivities of Free-Base- and Zn(II)-N-Methyl Hydroporphyrin Compounds. The Unexpected Selectivity of the Direct Methylation of Free-Base Hydroporphyrin Compounds

“…44 Octaalkylporphyrins are typically reduced with sodium metal in isoamyl alcohol. 42,[62][63][64] The strongly basic conditions of the reaction results in equilibration to the thermodynamically preferred trans-hydrogenation product but requires use of the iron complex rather than the free-base to prevent formation of the nonreducible porphyrin dianion. With proper manipulation of the reaction conditions, gram quantities of chlorin can be obtained pure without chromatography.…”

Synthesis and Stereochemistry of Hydroporphyrins

“…trans-OEC is best prepared by reduction of Fe(III)(OEP)Cl with sodium in amyl alcohol, and subsequent demetalation of the formed Fe(OEC). 19,21 " 22c The Sn(IV) and Mn(III) complexes of OEP can be reduced in comparable yield to the metallochlorin, [21][22][23][24] but demetalation is less satisfactory in this case for preparative purposes. 24 Considerable attention has been given to the influence of the central metal on the reduction of metalloporphyrins.…”