Approaches towards the synthesis of a 2,9,16,23-tetrasubstituted phthalocyanine as a pure isomer

Abstract

, 1059 (1988). Treatment of 4-neopentoxyphthalonitrile with hydrogen sulfide gas yielded 1-irnino-6-neopentoxy-3-thioisoindoline and 1-irnino-5-neopentoxy-3-thioisoindoline, which on alkylation with iodomethane gave 1 -imino-3-methylthio-6-neopentoxyisoindolenine and 1-imino-3-methylthio-5-neopentoxyisoindolenine. The methylthioisoindolenines readily condensed at room temperature to a mixture of tetrasubstituted phthalocyanines and a series of linear open-chained purple compounds characteristic of isoindigos, while condensation at -20°C in the presence of zinc acetate gave, in at least one experiment, 2,9,16,23-tetraneopentoxyphthalocyanine as a pure isomer. The low temperature formation of phthalocyanines is remarkable and the syntheses described herein provide guidelines for the synthesis of pure isomers of 2,9,16,23-tetrasubstituted phthalocyanines. The purple and red compounds are shown to have isoindigo structures rather than a ring-opened phthalocyanine structure as previously reported.SHAFRIRA GREENBERG, A. B. P. LEVER et CLIFFORD C. LEZNOFF. Can. J. Chem. 66, 1059 (1988). La rkaction du nkopentoxy-4 phtalonitrile et du sulfure d'hydrogbne gazeux conduit i I'imino-1 ntopentoxy-6 thio-3 isoindoline et a I'imino-1 nkopentoxy-5 thio-3 isoindoline qui, par alkylation avec I'iodomkJhane, conduisent B I'imino-1 mkthylthio-3 nkopentoxy-6 isoindoline et a I'imino-1 mkthylthio-3 nkopentoxy-5 isoindoline. A la temptrature ambiante, les mCthylthioisoindolines se condensent facilement pour donner un mklange de phtalocyanines tttrasubstitukes et une strie de composts linkaires pourpres caractkristiques des isoindigos; par ailleurs, une condensation B -20°C, en prtsence d'acttate de zinc, a conduit-au moins dans une experience-i la tttrankopentoxy-2,9,16,23 phtalocyanine sous la forme d'un isomere pur. La formation de phtalocyanines 2 basse tempkrature est remarquable et les synthbses dtcrites dans ce travail fournissent des indications sur les mkthodes de synthese des isombres purs des phtalocyanines substitutes en 2,9,16,23. On a dtmontrt que les composts pourpre et rouge possedent des structures relikes B celle de I'isoindigo plut6t que des structures relikes a celle de la phtalocyanine qui avaient kt6 suggkrkes antkrieurement.[Traduit par la revue]Tetrasubstituted phthalocyanines having one substituent on each of the four benzo rings of phthalocyanine have been known for some time (1) but have received more attention recently due to their importance in electrocatalytic studies (2, 3). Most tetrasubstituted phthalocyanines are prepared by self-condensation of a suitable 3 or 4-substituted phthalonitrile or derivative (4, 5). For example, the isoindoline of 4-neopentoxyphthalonitrile will, upon condensation, give not only 2,9,16,23-tetraneopentoxyphthalocyanine (1) but also the 2,10,16,24-, 2,9,17,24-, and 2,9,16,24-tetraneopentoxyphthalocyanine isomers (6, 7). Indeed, we have shown that the 2,9,16,23-tetraneopentoxy hthalocyanine zinc(11) (2) derivative exhibited P peaks in its H nmr spectrum, indicating the presenc...

The syntheses of 2,9,16,23- and 1,8,15,22-tetrahydroxyphthalocyanines

“…Since 4-hydroxyphthalonitrile (12) is unable to react with trityl chloride to give the corresponding ether and is unstable to basic conditions, 1 2 was treated with dimethoxymethane (13) or diethoxymethane (14) under acidic conditions (29) to give 4-methoxymethoxyphthalonitrile (15) and 4-ethoxymethoxyphthalonitrile (16) in 92 and 95% yield, respectively. 2,9,16,23-Tetra(methoxymethoxy)phthalocyaninato zinc(I1) (17) was prepared from 1 5 in 30% yield in a previous procedure (23), but similar treatment of 16 gave mostly decomposition products.…”

“…Although the 2,9,16,23-tetraneopentoxyphthalocyaninato zinc(I1) (16) and 2,9,17,24-tetra-tert-butylphthalocyaninato zinc(I1) (17) were produced as pure isomers; several reaction steps were used and only low yields were obtained. The synthesis of a single isomer of I,2-naphthalocyanine has been achieved (18) due to the steric constraints of the benzo substituents, but other 1,8,15,22-tetrasubstituted phthalocyanines gave mixtures of isomers that in one example could be separated by high performance liquid chromatography (HPLC) (19).…”

Template synthesis of polyazamacrocyclic compounds

“…In rare cases (for example, if R = OCH2C6H5-p-C4H9, 3-OCH3 or OCH2C(CH3)3 and M = Zn) the condensation of 3-substituted phthalonitriles or their derivatives proceeds with single isomer formation [466,4671. Thus the condensation reaction of L615 or L616 at -20°C in DMF using Zn(CH3C00)2 as a template source gave [Zn( L614)] [468] as single structural isomer, together with a mixture of starting ligsons and byproducts from the linear condensation of two, three or four blocks, L617-L621 (Eq. Development of low-temperature template syntheses should also be important in this context [467].…”

The use of bisphthalonitriles in the synthesis of side-strapped 1,11,15,25-tetrasubstituted phthalocyanines

“…Single isomers of 2,9,16,23-(2), 2,9,17,24-(3), and 1,8,15,22-tetrasubstituted phthalocyanines (4), and a 1,2-naphthalocyanine (5) have been prepared capitalizing on reactive substrates (2) or electronic (3) or steric constraints (4,5) but inethods towards the synthesis of pure 1,11,15,25-tetrasubstituted phthalocyanines have been only briefly reported by us in a preliminary coinmunication (6 Having established that phthalocyanines containing bulky substituents at positions adjacent to the macrocyclic core are readily prepared, we directed our attention towards the preparation of bisphthalonitriles bridged at the 3-position, for eventual dimerization to 1,11,15,25-tetrasubstituted phthalocyanines. Earlier, we had suggested (12) that P-hydrogens on substituents could lead to p-elimination reactions under the basic conditions of PC formation and hence we concentrated our attention on bridging groups containing no hydro, oens at the P-position, particularly P,P-dialkyl groups.…”