J. Chem. SOC. (C), 1966

meso-Substitution Products of Rtioporphyrin I By A. W. Johnson and Diane Oldfield

Schiff‘s base derivatives have been prepared from meso-aminoztioporphyrin I. The Vilsmeier reaction wi th aetio- porphyrin I leads to the meso-chloro-derivative but wi th the nickel complex of the porphin the meso-formyl com- pound is produced which has been characterised as its oxime, hydrazone, and Schiff’s bases with aromatic alde- hydes. Dehydration of the oxime yields meso-cyanoaetioporphyrrn I which can be hydrolysed to the meso- carboxy-derivative. The visible and n.m.r. spectra of these derivatives are sumrnarised.

IN a recent Paper we described a series of meso-nitro- derivatives of xtioporphyrin I , and the reduction of mononitroztioporphyrin I to the corresponding meso- amino-derivative (I ; R = NH,) which was characterised as its N-acetyl and copper derivatives. The visible and n.m.r. spectra of the porphins are very characteristic and variation of the porphin substituents causes marked changes in these spectra, consequent on the size and electronic properties of the substituents. We now des- cribe some further meso-subst itutioii products of ztioporphyrin I and their spectra. Thus, when mono- aminoaetioporphyrin I is condensed with benzaldehyde it is converted into the corresponding Schiff’s base ( I ; R = NXHPh), which showed a visible spectrum (Table 1) of the “ phyllo ” type 2 although with peaks I and I11 strongly depressed, and an infrared spectrum which contained a prominant band at 1638 cm.-l corresponding to the C=N group. In the n.m.r. spectrum of ( I ; R = N:CHPh) (Table 2), the resonances associated with the porphyrin alkyl substituents were at T values similar to those of mononitrozetioporphyrin I , thus suggesting a greatly diminished mesomeric interaction between the meso-nitrogen substituent and the porphyrin ring compared with that in the parent amino-compound. The proton of the methyleneimino-group corresponded to a signal a t -0.2 T, which is appreciably lower than the signal of the similar proton of benzylideneaniline (1.7 T),

owing to the influence of the large porphyrin ring current. In the corresponding condensation product ( I ; R = N:CH*C,H,*ONe) from p-anisaldehyde and monoamino- aAioporphyrin I, the presence of the methoxy-group

?NH LN HN “4 E t W M e

E t

, Me

E t I

I (11) Ctl2

Me ( I . )

CH2 - C02Me

raised the methyleneimine proton resonance to +0.3 7:

(Table 2 ) . The visible spectrum (Table 1) of this product 1 -4. W. Johnson and Diane Oldfield, J . Chenz. SOC., 1965,4303. 2 A. Stern and F. Pruckner, 2. phys. Chem., 1937, A , 180, 321,

3 V. I. Minlrin and G. N. Dorofeenlro, Rztss. Chem. Rev., and earlier Papers.

1960, 29, 599.

was almost identical with that of benzylideneamino- ztioporphyrin I.

In an investigation of other electrophilic substitutions of ztioporphyrin I we have examined the formylation under Vilsmeier conditions, i.e., with phosphorus oxy- chloride and NN-dimethylf~rmarnide.~ When equi- molecular quantities of ztioporphyrin I and phosphorus oxychloride were employed in NN-dimet hylformamide as solvent two products were obtained, both in low yield. The main product (16%) showed no strong in- frared absorption in the carbonyl region, suggesting that formylation had not occurred. Analysis indicated the presence of chlorine and on the basis of the “ phyllo ” type of visible spectrum and the n.m.r. spectrum it was concluded that the product was meso-monochloro- Ztioporphyrin I. The nickel complex was also prepared. The second product (2”/) also showed a “ phyllo ” type spectrum which showed a bathochromic displacement compared with that of the monochloro-derivative. It was probably a dichloro-derivative but the amount obtained was not sufficient to permit complete charactens- ation. We have been unable to obtain meso-acetyl- ztioporphyrin I from a Vilsmeier reaction with NA7-di- methylacetamide and phosphorus oxychloride. At this stage, Professor Inhoffen kindly informed us that, with H. V ~ i g t , ~ he had obtained a monoformylocta-alkyl- porphin (diethyl, tetramethyl, and dipropyl P-sub- stituents) by the Vilsmeier formylation of the porphin nickel complex followed by removal of the nickel with acid. We have confirmed this observation with xtio- porphyrin I and have carried out some further trans- formations of the formyl derivative. Mesomeric inter- action between the formyl group and the porphyrin ring was suggested by the carbonyl infrared absorption at 1697 cm.-l (cf. ref. 5) and the fact that only one formyl derivative was obtained even after treatment with excess of reagent, indicating that the formyl group deactivates the remaining meso-positions towards further electro- philic attack. However, (3-formylporphins are stated to show carbonyl infrared bands a t 1658-1665 cm.-1,6 and as the formyl group is not sterically hindered in these derivatives, it appears that there is only partial meso- meric interaction of the nteso-formyl group with the porphin nucleus in the meso-formyl derivative. The

Braunschwcig, 1964.

354.

A 4, 579.

4 H. Voigt, Dr. rer. nat. Dissertation, Technischen Hochschule,

5 L. H. Cross and A. C. Rolfe, Traszs. Faraday SOL., 1951, 47,

ti J. E. Falk and J. B. Willis, Aztstval. J . Sci, Rcs., 1951,

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Org . 795

TABLE 1

Visible spectra of aetioporphyrin I and some meso-substituted derivatives in chloroform Ll,,. Emax.)

Band 111 Band I1 528 (9.5) 566 (5.95) 553 (5.42) 586.5 (3.63) 543 (3.04) 580 (4.64) 544-5 (2.9) 552 (4-2) 538 (6.9) 577 (6.6) 535 (6.13) 569 (4.4) 553 (13.4) 587 (5.76) 535 (7.5) 572 (5 .8) 537 (6-28) 574 (5.05) 536.5 (8.8) 569.5 (6.79) 534 (6 -8 ) 569 (5.7) 535 (6-8) 570 (5.9)

7

Spectrum t Y Pe E t i o

Phyllo Yhyllo E t i o E t i o

E t i o

E t i o K t i o E t i o

-

-

-

r

Soret band 399.5 (160) 416 (158) 414 (144) 415 (144) 407 (142) 401 (127) 405.5 (145) 402 (154) 407 (148) 402 (160) 404 (147) 405 (147)

Band IV 496 (13.6) 519 (11-75) 512 (13.0) 512 (12.9)

500 (10.4) 515 (9.96) 500 (12.8) 505 (11.2)

501 (12.4) 502 (12.7)

509 (9.7)

501 (13.3)

~~ ~

Band I G21 (5.18) 646 (6.38) 634 (0-76) 636 (0.66) 633-5 (4.2) 618-5 (2.8) 640.5 (13.3) 620 (3.9) 628 (2.78) 623 (4.12) 628 (2.7) 629 (2-8)

Porphin Xtioporphyrin 11 ................................. Amino- 1 ................................................ Benzylideneamino- ................................. P-Rnis ylideneamino- ..............................

Oximinoformyl- .................................... Cyano- ................................................ Carboxy- ............................................. Hydrazone of formyl-. ............................. Hydroxymethyl- .................................... Pheny Iimino-methylene- ...........................

Formyl- ................................................

~-Methoxyphenylimino-methylene- ............

TABLE 2

N.m.r. signals of some meso-substituted ztioporphyrins I in trifluoroacetic acid Phenyl protons

(4 -

1.1 1-8

1.1 1-8

-

-

-

-

-

-

1-8 2.1

1.7 2.5

Imino- protons (s)

9.01 10.41)

12-65 13.8

12.64 13.8

12-8 13-5

13-4 14.2

13.4 (2)

13.75 14.25

12.55 13-5

13.8 14-1

11.6 12.5

11.6 12.7

P-Methyl protons (s)

6-73 (6) 6.78 (3) 6.92 (3) 6.3 6.45 6-7 6.26 6.43 6.7 6.3 (6) 6.45 (3) 6.75 (3) 6.3 (6) 6.5 (3) 6-8 (3) 6-2 (3) 6.25 (9) 6-3 (6) 6.4 (3) 6.5 (3) 6.34 (6) 6.5 (3) 6.9 (3) 6.35 (6) 6.5 (3) 6.6 (3) 6.4 (6) 6.55 (3) 6.85 (3) 6.35 (6)

6.82 (3) 6.5 (3)

Meth ylene-imine proton (s) -

meso- Meso substituent Protons (s)

Amino-’ ................................. +0-56 (PJ) -t0.99 ( Y )

Benzylideneamino- .................. -0.9 ( P J ) -0.8 ( Y )

5.8 8.25 (9) 8.6 (3)

- 0-2

p - Anis ylideneamino- .................. -0.89 (P,S) -0.8 ( Y )

5.8 8.25 8.6

+ 0.3

Formyl- ................................. - 0.8 (P.8) -0.75 ( y )

5.83 8.3 -2.65 (CHO)

Oximinoforrnyl- ........................ -00.8 (P,S) -0.7 ( Y )

5-8 8.25 (9) 8.6 (3)

Cyano- .................................... -00-97 (3) 5.75 8.2

Carboxy- ................................. -0.9 ( p a -0.8 ( Y )

5.8 8.25

Hydrazone of formyl-. ................. -0.75 (P,S) -0.7 ( Y )

5.8 8.2 (9) 8.7 (3)

5.75 8.3

- 1-45

H ydroxymeth yl- ........................ -0.75 (p,S) -0.65 ( y )

2-1 (CH,O)

Phenylimino-methylene- ............ - 0-72 (p,S) -0.70 ( y )

6.0 8.4 - 1.7

9-Methoxyphenylimino-methylene- - 0.75 (P,S) -0.72 (Y)

5-0 8-3 - 1.58

visible spectrum (Table I) is still of the “iEtio ” type, like that of the corresponding oxime (I ; R = CHZNOH). The n.m.r. spectrum of the oxime is similar to that of the meso-nitro-derivative except that the methyls of the ethyl groups were revealed as two distinct triplets, as in the case of the N-acetylamino-derivative, because of the larger size of the oximinoformyl group.

Dehydration of meso-oximinoformylEtioporphyrin I with acetic anhydride gave meso-cyanoaetioporphyrin I (I; R = CN) which showed a sharp nitrile peak at

2215 cm.-l in the infrared spectrum suggesting strong conjugation of the nitrile with the porphin ring.’ The visible spectrum was of a type (intensities of band I11 > I > IV > 11) not so far described in the liter- ature, and the spectrum showed a marked bathochromic displacement compared with ztioporphyrin I itself. The n.m.r. spectrum of a solution of the nitrile in tri- fluoroacetic acid showed certain deviations from the spectra of other mono-meso-substituted porphins in ‘ R. E. Kitson and N. E. Griffith, Analyt. Chem., 1952,24, 334.

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J. Chem. SOC. (C), 1966

this solvent. In the first place, the three meso-protons absorbed as a singlet which suggests that the buckling of the molecule caused by the nitrile group is small, and this view is supported by the resonances of the methyl substituents which appear as two singlets with a spread of only 0.05 T. The signal equivalent to three protons is a t lower field than that equivalent to nine protons. Only two imino-protons appeared to be present which suggests that the effect of the nitrile group is to reduce the basicity of the porphin so that protonation does not occur on the imino-nitrogen atoms. This accords with the observation that the cyanoporphin did not form metal complexes. Cyano- ztioporyhyrin I did form a monohydrobromide however and i t is possible that the protonation might involve the nitrile group. Hydrolysis of the cyanoporphin with sul- phuric acid gave meso-carboxyztioporphyrin I (I ; R = C0,H) in good yield. The infrared spectrum of the product contained a strong absorption at 1690 cm.-l associated with the acid carbonyl group. This may be compared with a value of 1666 cm.? for the similar group in a rhodochlorin8 and suggests that the mesomeric interaction of the meso-carboxy-group and the porphyrin nucleus is weak. The visible spectrum was of the " zt io " type and the n.m.r. spectrum of a solution in trifluoroacetic acid resembled that of mononitroztio- porphyrin I,I again suggesting a weak interaction of the aromatic ring with the meso-substituent.

In a preparation of the hydrazone of meso-formyl- ztioporphyrin I, two fractions were obtained by chromatography of the crude product. The first (ca. 20%) was ztioporphyrin I itself and it was later found that &ioporphyrin was always obtained in varying amounts when solutions of the meso-formyl derivative or its hydrazone were heated. The second fraction con- sisted of two compounds which were separated by further chromatography on deactivated alumina. The two compounds had almost identical visible spectra and each analysed for the hydrazone of monoformylztioporphyrin I (I; R 7= CH:N*NH,) so that they are considered to be the syz- and anti-geometrical isomers. Attempts to reduce the formylhydrazone group to methyl by the Wolff-Kischner procedure again gave aetioporphyrin I. Reduction of meso-formylztioporphyrin I with sodium borohydride (cf. ref. 4) gave the meso-hydroxymethyl derivative ( I ; I3 = CH,OH), the visible spectrum of which was still of the " xtio " type and showed a small bathochromic shift compared with that of ztiopor- phyrin I.

Condensation of the monoformylporphyrin with aniline gave the Schiff's base (I; R = CH:NPh) in high yield. The infrared spectrum of the product showed strong peaks at 1634 ( G N ) and 1598 and 1495 cm.-l (aromatic C=C) and the visible spectrum was of the " Etio " type with a small hypsochromic shift compared with the spectrum of the parent formylaetioporphyrin I . The n.m.r. spectrum in trifluoroacetic acid was typical of a

* H. R. Wetherell, M. J . Hendrickson, and A. R. McIntyre, J . Amev. Chem. SOC., 1959, 81, 4517.

Pneso-substituted porphin except for the very low signal associated with the imino-protons. Inspection of models has shown that if the meso-substituent is twisted out of the plane of the porphin molecule, the phenyl group can take up a position in which the imino-protons are in the area of negative shielding caused by the phenyl group. The condensation product of 9-anisidine and formyl- ztioporphyrin I was also prepared. The n.m.r. spectrum of this product was similar to that of the aniline derivative except that the signal associated with the methine proton was at higher field owing to the effect of the methoxy- group.

Several meso-formyl-porphins and -chlorins were described by H. Fischer and his students9Vl0 but were usually prepared by oxidation of the corresponding meso-methyl derivatives rather than by direct nzeso- formylation. A study was reported lo*ll of the reaction of the so-called y-formylpyrroporphyrin methyl ester (11), and many of these are paralleled by the trans- formations described in the present paper.

EXPERIMENTAL

Ultraviolet and visible spectra were determined on chloro- form solutions on a Unicam S.P. 700 spectrometer. Infra- red spectra were determined on a Perkiii-Elmer Infracord, model 137, and refer to potassium bromide discs. X.1n.r. spectra were determined on trifluoroacetic acid or deutero- trifluoroacetic acid (DTFA) solutions on a Perkin-Elmer R10 instrument operating a t 60 Mc./sec. using tetraniethyl- silane as internal reference. Light petroleum had b. p. 40-60".

Condensation of meso-,~~ononininoatiopovpliqlrin I with Aromatic Aldehj,des.--(i) Benzaldehyde. Monoaminoztio- porphyrin I (30 mg.) was dissolved in benzaldehyde (12 nil.) and the purple solution stirred overnight a t room temperature. Aqueous methanol (12 nil, ; 1 : 5) was added to the red solution and the resultant red precipitate sep- arated, and the product crystallised from chloroform- methanol as deep blue shiny plates (30 mg. ; 8276) (Found : N, 11.6. C,,H,,N, requires h', 12.00/); v~, , . .~ . 1460, 1580 (aromatic C=C), 1635 (C=N), 2940, and 3300 cni.-l.

(ii) p-Anisaldehyde. The analogous Schiff's base was obtained from p-snisaldehyde as deep blue prisms (chloro- forin-methanol) . In this case, stirring was maintained for 24 hr. (Found: C, 78.5; H, 7.49; N, 12.45. C,,H,,N,O requires C, 78.8; H, 7.41; S, l l-450/,); v,,,. 1240 (C-O), 1410, 1460, 1580 (aromatic C=C), 1632 ( G S ) , 2946, and 3294 cm.-l

nieso-MonochZororrctiopo~~?z~~~n I .--Phosphorus osy- chloride (2 nil.) was added slowly to N,r\'-diniethylformarliide (48 nil.; dried over MgSO,) and cooled in an ice-bath. This was left at room temperature for 30 min., during which time the colourless solution changed to pink. Btioporphyrin I (50 mg.) was dissolved in dimethylforni- amide (200 ml.) and to this was added one inol. of phos- phorus oxychloride and the solution heated under reflux for 1 hr., poured into water ( 1 1.) containing sodium hydroxide (1 g.) , and warmed on a water-bath for 1 hr. The orange

H. Fischer and H. Kahr, Annalen, 1937, 531, 209; 13- Fischer and M. Strell, ibid., 1940, 543, 143.

lo 13. Fischer and E. Stier, Annalen, 1939, 542, 224. l1 H. Fischer and W. Kanngiesser, Annalen, 1940, 543, 271.

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Org. 797

precipitate was collected on diatomite, washed well with water, and dissolved in benzene. The benzene solution was dried and chromatographed on an alumina column (3 x 60 cm.) eluted with benzene. The first band was pale orange with a " phyllo " type spectrum. The second band, deep orange, was collected and crystallised froni benzene as red- dish-brown long needles (8 nig.; 16%) (Found: C, 74-9; H, 7.47; C1, 7.58; N, 10.8. C,,H,,ClK4 requires C, 74.89; H, 7.27; C1, 6.9; K, 10.90,;). No carbonyl stretching frequency was observed in the infrared spectrum. The third band was unchanged aetioporphyrin I (24 mg.).

Repeating the above experiment but pouring the re- action product directly into water and collecting the pre- cipitate immediately, and omitting the alkaline hydrolysis, we obtained the same products in similar yield.

The nickel complex was obtained as deep red needles by heating the monochloroporphyrin (1 5 mg.) in chloroform (10 ml.) with nickel acetate (10 mg.) in methanol (5 ml.) under reflux for 1 hr. Reduction of the solvent volume gave the crystalline product (9 mg.; 54%) (Found: C, 67-05; H, 6.0; N, 9.1. C,,H,,C1N4T\l;i requires C, 67.45; H, 6.2; C1, 6-2; N, 9.8:h) ; Amax 406.5, 531-9, and 563-6 mp; emax. 121,000, 7690, and 9720, respectively.

meso-MonoformyZci?tioporPhyrin. (Cf. ref. 4.)--Freshly dis- tilled phosphorus oxychloride (13-7 ml.) was added dropwise to dry dimethylformamide (10 ml.) cooled in an ice-bath, and the solution left a t room temperature for Q hr. An aliquot portion of this solution (2.4 ml.) was warmed on a water-bath to 50" and a solution of nickel ztioporphyrin I (100 mg.) in dry 1,2-dichloroethane (75 ml.) was added dropwise with vigorous stirring, the temperature being kept a t 50-55" for ca. 15 min. The solution was then warmed for 30 min., the colour changing from red to green. A saturat.ed solution of sodium acetate (75 ml.) was added and stirring and heating continued for a further 2 hr. The organic phase was separated and the water phase extracted with ether (2 x 50 ml.) which was added to the organic layer. The organic solvents were removed under reduced pressure, the residue dissolved in chloroform, and chromato- graphed on an alumina column (2 x 20 cm.), eluted with more chloroform. The first band to be eluted was deep green and this was collected and the product crystallised from chloroform-methanol in long red felted needles (98 nig.; 840,;) (Found: C, 70.7; H, 6-15; N, 9.72. C,,H,,N4Ni0 requires C, 70.3; H, 6.6; N, 9-9CjL); Amax. 407.5, 428, 532, 566, and 658.5 mp; E ~ , ~ ~ . 72,300, S1,500, 4330, 6650, and 8630, respectively; vmax. 1697 cm.-l.

The above nickel complex (85 mg.) was dissolved in con- centrated sulphuric acid (75 ml.) and the green solution stirred overnight. The product was poured cautiously into ice-water (200 nil.) and gave a brown precipitate which was separated, dissolved in the minimum of chloroform (15 ml.) and chromatographed on an alumina column (24 x 50 cm.), eluted with more chloroform. The first band to be eluted was pale pink followed by a deep green band which was eluted as a deep purple solution. This was collected and the product crystallised from chloroform- methanol in deep purple needles (60 mg.; 78%) (Found: C, 78-2; H, 7-5 ; N, 11.05. C,,H,,N,O requires C, 78.5; H, 7.5; N, 11.15%); vmax 1698 ( G O ) and 2878 (aldehyde C-H stretching) cm.?.

Oxime of Monoformyl~tioporphyvin I .-Monoformylaetio- porphyrin I (50 mg.) and hydroxylamine hydrochloride (30 mg.) were dissolved in pyridine (70 ml.) and the deep purple solution heated on a water-bath for 30 min., the

colour changing from purple to red. The red solution was poured into water (100 ml.), the red precipitate separated, washed well with water, and dissolved in chloroform. This was dried, the volume reduced, and the solution chro- matographed on an alumina column (2 x 40 cm.) eluted with chloroforni. A pale pink band (ztioporphyrin I) was eluted iollowed by a narrow brown band followed by a deep red band. The last band was collected and the pro- duct crystallised from chloroform or chloroform-methanol in deep purple prisms (30 mg.; 58%) (Found: C, 78.2; H, 7.6; N, 11.0. C,,H,,N,O requires C, 78-15; H, 7.75; N, 11-050/,). Extension of the reaction time resulted in the formation of more aetioporphyrin I.

meso-Monocyanocztioporfihyrza 1: .-(i) The foregoing oxime (30 mg.) was dissolved in acetic anhydride (30 ml.) and heated under reflux for 1 hr. The product was poured into water (30 ml.) and stirred gently for 30 min. whereupon the product was obtained as long purple needles. These were collected and crystallised from chloroform-methanol (20 mg.; 66oj) (Found: C, 78.3; H, 7.0; N, 13.3. C,,H,,N, requires C, 78-7; H, 7.4; N, 13.90/,); wmax. 2190 cm.-l and (in CHC1,) 2215 cm.-l. The cyanoporphyrin dissolved in acids to give a bright blue solution; Lax (trifluoroacetic acid) 409, 566-5, and 616 mp; E,,, 282,000, 11,400, and 12,800, respectively.

(ii) Monoformylztioporphyrin (25 mg.) , sodium formate (100 mg.), and hydroxylamine hydrochloride (25 mg.) were dissolved in formic acid (10 ml.; 98%), and the blue solution heated under reflux for 1-5 hr. Water (20 ml.) was added and the product extracted into chloroform. The chloroform solution was washed with sodium hydrogen carbonate solution, then water, and the volume of the chloroform solution reduced (5 ml.). The solution was chromatographed on alumina, eluted with chloroform. The first green band was the starting material (5 mg.) slowly followed by the diffuse purple band of the cyano- porphyrin. This was collected and the product ( 3 mg.; 13 yo) crystallised from chloroform-methanol.

The cyanoporphyrin (20 mg.) was dissolved in a minimum of hot chloroforni (4 ml.) and one drop of hydrobromic acid in glacial acetic acid was added. An immediate colour change from purple to green was observed and the hydro- bromide was precipitated by dropwise addition of light petroleum. The green precipitate was separated (19 mg. ; 81 yo) and crystallised from chloroform-light petroleum. Attempts to prepare the nickel complex of the cyano- porphyrin were unsuccessful.

nieso-MonocarboxyetiopoyPhyrin I.- Monocyanoxtio- porphyrin (50 mg.) was dissolved in concentrated sulphuric acid ( 5 ml.) and the resultant blue solution heated on a steam-bath for 45 min. The solution was poured cautiously into ice-water (20 ml.) and the red flocculent precipitate extracted into chloroform (2 x 20 ml.). The chloroform extract was washed with sodium hydrogen carbonate solu- tion, then water, the solution dried, and the volume reduced (5 nil). The solution was chromatographed on an alumina column (2Q x 20 cm.), eluted with chloroform. The first pale pink band to be eluted was aetioporphyrin and was followed by a narrow deep red band which was collected and the product crystallised from benzene in small deep red prisms (41 mg.; 80%) (Found: C, 76.0; H, 7-5; N, 10.1. C,,H,,N,O, requires C, 75.8; H, 7.35; N, 10*97/0); wms. 1690 cm.-'.

Hydrazone of meso-Mono formyla?#ioporphyrin I .-Mono- formylztioporphyrin I (100 mg.) was dissolved in pyridine

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J. Chem. SOC. (C), 1966 (130 ml.), hydrazine hydrate (10 ml.) was added, and ethanol added dropwise until the solution was homogeneous. The product was heated under reflux for 1 hr. then poured into water. The brown precipitate was collected, washed well with water, and dissolved in chloroform. The chloroform solution was dried, the volume reduced (5 ml.), and chrom- atographed on an alumina column (2.5 x 40 cm.) eluted with chloroform. The first band to be eluted was deep pink and the product crystallised from chloroform-meth- anol (20 mg.) and shown to be ztioporphyrin. The next two bands (deep red) were difficult to separate on this chromatogram, but were subsequently separated by chromatography on alumina (deactivated with 6% water) and eluted with benzene. The first broad red band was collected (50 mg.; as./,) and crystallised from benzene- light petroleum (b. p. 60-80”) (Found: C, 76-1; H, 7-75; N, 16.55. C33H40N6 requires C, 76.05; H, 7.75; N, 16.1%) ; v,,~ 1640, 3240, and 3450 c1m-l. The second narrow red band was eluted and the product crystallised from benzene- light petroleum (b. p. 60-80”) as small red prisms (8 mg. ; 3%) (Found: C, 7 5 7 ; H, 8.0%). This product had a visible spectrum identical with that of the above compound and it is probably a geometric isomer of the above hydrazone.

meso-HydroxymethyZ~tioporph_vrin.. (Cf. ref. 4.)-Mono- formylretioporphyrin (50 mg.) was dissolved in chloroform (30 ml.), a solution of sodium borohydride (20 mg.) in aqueous ethanol (35 ml.; 1 : 6) was added, and the homogeneous solution stirred overnight at room temperature. Water (30 ml.) was added, the organic layer separated, and the solvent removed. The residue was dissolved in chloroform (7 ml.) and the solution chromatographed on an alumina column (2 x 15 cm.) eluted with more chloroform. Only one main orange band was observed. This was collected and the product (35 mg.; 70%) crystallised from chloro-

form (Found: C, 78.0; H, 7.9; N, 12.95. C,,H,N,O requires C, 78.0; H, 7.95; N, 13.05%).

Condensation of F o m y l a t q h w f l h y y i z with Aromatic Bases.-( i) A niline. Monoform y l z tioporphyrin (50 mg. ) was dissolved in freshly distilled aniline (20 ml.) and the deep purple solution heated on a steam-bath for 1 hr. Addition of light petroleum gave a finely dispersed pre- cipitate which was collected on diatomite and washed well with light petroleum. The precipitate was dissolved in a minimum of chloroform and chromatographed on an alumina column (3 x 40 cni.). The first band to be eluted was aztioporphyrin followed by a broad orange band which was collected, and the product crystallised from chloroform- methanol in brown fine needles (51 mg.; 9O”/b) (Found: C, 80.0; H, 7.9; N, 11.9. C39H43N5 requires C, 80.5; H, 7.4; N, 12-050/,); vmttX. 1495, 1594 (aromatic C=C), and 1634 (C=N) cm.-l.

Monoformylaztioporphyrin (50 mg.) and 9-anisidine (25 mg.) were dissolved in glacial acetic acid (75 ml.) and the blue solution was heated on a water-bath for 30 min. A slight colour change from blue to blue-green was observed. The solution was poured into water (100 ml.) and the product isolated as above. The first band to be eluted was Etioporphyrin (5 mg.) followed by a broad orange band which was collected, and the product crystal- lised froni benzene in red needles (45 mg.; 80.5o/b) (Found: C, 79.0; H, 7-1; K, 10.9. C,,H,,N,O requires C, 78.55; H, 7.4; N, 11.450/); vmax. 1245 (C-0), 1510 (aromatic G C ) , and 1630 ( G N ) cin.-l.

We thank the Science Research Council for the award of

(ii) p-Anisidine.

a Studentship (to D. 0.).

THE UNIVERSITY, NOTTINCHAM [5/1225 Received, November 16th, 19653

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