The reduction of organic compounds by metal-ammonia solutions

Birch, Arthur J.

doi:10.1039/qr9500400069

Cited by 229 publications

(83 citation statements)

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“…Compounds 23-25 are reduction products of the intermediates that would give 38. A photochemical system such as dicyanobenzene-phenanthrene in a protic solvent is potentially a reducing medium for any substrates with a reduction potential low enough to be reduced by The first electron transfer to 39 from the radical anion of 6 the dicyanobenzene radical anion (28). A-few similar photochemical systems have been reported.…”

Section: Irradiation In Acetonitrile-methanolmentioning

confidence: 99%

Radical ions in photochemistry. 15. The photosubstitution reaction between dicyanobenzenes and alkyl olefins

Borg¹,

Arnold²,

Cameron³

1984

Can. J. Chem.

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Can. J. Chem. 62, (785 (1984). ' The photosubstitution (electron transfer) reaction between 1,4-dicyanobenzene (1) and 2,3-dimethyl-2-butene (2), which gives I-(4-cyanophenyl)-2,3-dimethyl-2-butene (3) and 3-(4-cyanopheny1)-2,3-dimcthyl-I-butene (4). has been extended to other dicyanobenzene-olefin mixtures. Substitution of a cyano group occurs when both 1 or 1,2-dicyanobenzene (5) are irradiated in acetonitrile solution, in the presence of 2 or cyclohexcne (16). Under comparable conditions, 1.3-dicyanobenzene (6) failed to react. Little or no substitut~on was observed in any case when the olefin was methylpropene (19). ' The results for 1 and 5 are in agreement with empirical free energy calculations (Weller equation) for the electron transfer process which, however, fail to explain the general lack of reactivity of 1,3-dicyanobenzene. Phenanthrene (11) has been shown to photosensitize the photosubstitution reaction between dicyanobenzenes and 2. Under these conditions the olefin reacts with 6 predominantly at the 4-position, resulting in overall substitution of a hydrogen atom. This reaction occurs regiospecifically, resulting in the formation of only one of the two possible isomeric side chains. The mechanistic details of these reactions have been substantiated by means of deuterium labelling studies. The aromatic nitriles also undergo photosubstitution by 2, in acetonitrile-methanol solution, resulting in methanol-incorporated products. Whereas reaction with 1 or 5 results in substitution of a cyano group, 6 was observed to give isomeric dicyanocyclohexenes, resulting from initial reaction at the 4-position, followed by reduction. A detailed mechanism for this secondary photoreduction has been substantiated by deuterium labelling studies. The anomalous behaviour of 1,3-dicyanobenzene has been attributed to a difference in the react~vity of the radical anion. marquages par le deutCrium permettent de confirmer les dttails mkcanistiques dc ces rCactions. Les nitriles aromatiques, en solution dans des milanges d'acktonitrile et de methanol, subissent aussi des photosubstitutions par 2; il y a formation de produits ayant incorporC du mCthanol. Alors que la rCaction des composCs 1 ou 5 conduit a la substitution d'un groupe cyano, on a observC que le compost 6 donne des dicyanocyclohextnes isomkres qui resultent d'une rkaction initiale en position 4, suivie d'une riduction. Des Ctudes impliquant des marquages par du deuterium ont permis de confirmer le mCcanisme dCtaillC de cette photorCduction secondaire. On attribue Ie comportement anormal du dicyano-I ,3 benzkne a la diffkrence de rCactivitC de I'anion radical.[Traduit par le journal]

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Section: Irradiation In Acetonitrile-methanolmentioning

confidence: 99%

Radical ions in photochemistry. 15. The photosubstitution reaction between dicyanobenzenes and alkyl olefins

Borg¹,

Arnold²,

Cameron³

1984

Can. J. Chem.

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“…72,73,74 The regioselectivity of the Birch reduction depends on whether the substituent is electro-withdrawing or electro-donating. The intermediate radical anion tends to locate itself on the carbon ortho to an electro-withdrawing group and on the carbon meta to the electro-donating group in order to minimise the interactions.…”

Section: Aromatic Compoundsmentioning

confidence: 99%

The kinetics and mechanisms of organic reactions in liquid ammonia

Atherton

Page

2010

Faraday Discuss.

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“…Birch (1,2) has pointed out that a carbonyl group can be converted into a non-reducible species by acetal or lietal forination, but only if the resulting alltoxy group involved is neither benzylic nor allylic. Groups such as benzyl, benzyloxycarbonyl, and p-toluenesulfonyl, which are used to protect amino, hydroxy, or mercapto functions, are readily reilloved by the reducing action of sodium and liquid an~monia.…”

Section: Introductionmentioning

confidence: 99%

REDUCTIVE CLEAVAGE WITH METAL IN LIQUID AMMONIA: I. THE SELECTIVE CLEAVAGE OF THE BENZYLTHIO C—S BOND VERSUS THE BENZYLIDENEDIOXY C—O BOND IN METHYL S-BENZYL-4,6-O-BENZYLIDENE-2-THIO-α-D-ALTROPYRANOSIDES; THE INFLUENCE OF THE COSOLVENT 1,2-DIMETHOXYETHANE ON THE COURSE OF THE REACTION

Nayak¹,

Brown²

1966

Can. J. Chem.

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The improved solubility of methyl S-benzyl-4,6-O-benzylidene-2-thio-α-D-altropyranoside (1) in liquid ammonia diluted with 1,2-dimethoxyethane has permitted the selective cleavage by metallic sodium or lithium of the C—S bond to give methyl 4,6-O-benzylidene-2-thio-α-D-altropyranoside in 70–75% yield. On the other hand, the slight solubility of I in liquid ammonia alone results only in the completely hydrogenolyzed material, methyl 2-thio-α-D-altropyranoside, along with unchanged I.Generally, in liquid ammonia alone, reductive cleavage is rapid (15–20 min) and the benzylidene and benzyl groups are converted largely into toluene accompanied by a small amount of bibenzyl. In liquid ammonia – 1,2-dimethoxyethane mixtures the reaction is much slower (≥ 1.5 h); under these conditions the benzylidene and benzyl groups are converted to a larger extent into bibenzyl, the rest becoming toluene.The two strong infrared absorption bands (in Nujol) in the region of 766 to 778 cm−1 and 706 to 718 cm−1 have been assigned to the phenyl moiety of the benzylidene group, and the one strong band in the region of 702 cm−1 to the phenyl moiety of the S-benzyl group.

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The reduction of organic compounds by metal-ammonia solutions

Cited by 229 publications

References 0 publications

Radical ions in photochemistry. 15. The photosubstitution reaction between dicyanobenzenes and alkyl olefins

Radical ions in photochemistry. 15. The photosubstitution reaction between dicyanobenzenes and alkyl olefins

The kinetics and mechanisms of organic reactions in liquid ammonia

REDUCTIVE CLEAVAGE WITH METAL IN LIQUID AMMONIA: I. THE SELECTIVE CLEAVAGE OF THE BENZYLTHIO C—S BOND VERSUS THE BENZYLIDENEDIOXY C—O BOND IN METHYL S-BENZYL-4,6-O-BENZYLIDENE-2-THIO-α-D-ALTROPYRANOSIDES; THE INFLUENCE OF THE COSOLVENT 1,2-DIMETHOXYETHANE ON THE COURSE OF THE REACTION

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