Squaraine chemistry. Synthesis, characterization, and optical properties of a class of novel unsymmetrical squaraines: [4-(dimethylamino)phenyl](4'-methoxyphenyl)squaraine and its derivatives

Law, Kock‐Yee; Bailey, F. C.

doi:10.1021/jo00038a010

Cited by 114 publications

(66 citation statements)

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“…3 and 4 also suggest that the solid state properties of l b -l e are similar to those of l a , despite their unsymmetrical structures. These results are not unexpected in view of similar results obtained from other symmetrical and unsymmetrical squaraines and in view of the small substituent effect on the solid state properties (1,12,38). Studies of the photoconductivities of these compounds are underway.…”

Section: Solid State Propertiessupporting

confidence: 84%

“…The absence of any C=O stretchings at -1700 cm-' is very characteristic for squaraine (3,4,12). The spectral results here suggest that, even though there is asymmetrical charge distribution in the two phenyl rings as revealed by proton NMR spectroscopy, the electrons in the central C,O, unit are fully delocalized.…”

Section: Ch30mentioning

confidence: 50%

“…However, none of these squaraines is known to possess useful photoconductivity. The present study, as well as our previous work (1 1,12), represents an extension of these condensation reactions to teritar-aromatic arnines. The resulting compounds are intensely absorbing in the visible region and are found to be photoconductive in xerographic devices.…”

Section: Ch30mentioning

confidence: 54%

“…We recently reported the synthesis of 2, an analog of 4, using a (2+2) cycloaddition reaction (11,12). The intention here is to extend the cycloaddition approach to synthesize 4.…”

Section: Resultsmentioning

confidence: 99%

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Squaraine chemistry. A new approach to symmetrical and unsymmetrical photoconductive squaraines. Characterization and solid state properties of these materials

Law¹,

Bailey²

1993

Can. J. Chem.

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A new approach to l-(p-dimethylaminophenyl)-2-hydroxycyclobutene-3,4-dione (4), a precursor for the synthesis of symmetrical and unsymmetrical photoconductive squaraines, is described. In situ generation of p-nitrophenyl ketene, by the reaction of p-nitrophenylacetyl chloride and triethylamine in the presence of tetraethoxyethylene in anhydrous ether, results in a (2+2) cycloaddition between the ketene and the electron-rich olefin. The cycloadduct generated, 6, was hydrolyzed to give 1-(p-nitropheny1)-2-hydroxycyclobutene-3,4-dione (5) in 51% yield. Reductive alkylation of 5 by hydrogen in the presence of formaldehyde in DMF at 50-60°C affords 4 in 81 % yield. The overall yield of 4 is 41 % from tetraethoxyethylene and is significantly better than other preparative procedures of 4 based on a partial Friedel-Crafts reaction or an arylation reaction of a squaric acid derivative with an aniline, where yields ranging from 8.5% to 24% were reported. Condensations of 4 with 2 equivalents of N, N-dimethylaniline and its derivatives in refluxing 2-propan01 in the presence of 6 equivalents of tributyl orthoformate yield symmetrical squaraine l a and unsymmetrical squaraines lb-le. The synthesis is accomplished by a (2+2) cycloaddition -reductive alkylation -condensation reaction sequence and represents a new, cost-effective synthesis for photoconductive squaraines where the expensive squaric acid reactant is bypassed. The spectroscopic and the solid state properties of la-le have been studied. Results show that the properties exhibited by l a -l e are essentially identical to those exhibited by other photoconductive, symmetrical squaraines that are synthesized by other known processes. From the resemblance in solid state properties, la-le are expected to be photoconductive. This has indeed been observed in preliminary experiments.KOCK-YEE LAW et F. COURT BAILEY. Can. J. Chem. 71,494 (1993) On dCcrit une nouvelle approche pour la preparation de la l-(p-dimethylaminophCnyl)-2-hydroxycyclobut~ne-3,4-dione (4), un precurseur dans la synthese de squarai'nes photoconductrices symetriques et non-symetriques. La generation in situ du p-nitrophknyl cetene, par la reaction du chlorure de p-nitrophCnylacetyle avec la triethylamine en presence de tCtraCthoxy6thylene dans l'ether anhydre, conduit 2 une cycloaddition (2+2) du c$t&ne et de l'olefine riche en electrons. L'hydrolyse du cycloadduit, 6, ainsi gCnerC conduit 2 la 1-(p-nitrophCny1)-2-hydroxycyclobut&ne-3-done (5) avec un rendement de 51%. L'alkylation reductrice de 5 par de l'hydrogene en presence de formaldehyde dans de DMF, a 50-60°C, fournit le composC 4 avec un rendement de 8 1 %. Le rendement global de 4 est de 41% B p a i r du tCtrakthoxy6thylene et ce rendement est supkrieur a ceux obtenus lors de preparations impliquant une reaction de Friedel-Crafts partielle ou une reaction d'arylation d'un derive de l'acide squarique avec de l'aniline alors que les rendements rapportks sont de l'ordre de 8,5 a 24%. Les condensations de 4 avec deux equivalents de N,N-dimethylanil...

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Section: Solid State Propertiessupporting

confidence: 84%

Section: Ch30mentioning

confidence: 50%

Section: Ch30mentioning

confidence: 54%

“…We recently reported the synthesis of 2, an analog of 4, using a (2+2) cycloaddition reaction (11,12). The intention here is to extend the cycloaddition approach to synthesize 4.…”

Section: Resultsmentioning

confidence: 99%

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Squaraine chemistry. A new approach to symmetrical and unsymmetrical photoconductive squaraines. Characterization and solid state properties of these materials

Law¹,

Bailey²

1993

Can. J. Chem.

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“…[1,2] To achieve their selective synthesis in fewer steps still constitutes a challenge. Use in synthesis of cyclobutadienes [3,4] and cyclobutanones, [5] among the four-membered carbocycles, is well documented, whereas use of cyclobutene derivatives [2,6] lacks general access routes although there are examples displaying optical [7] or biological [8] properties. Cyclobutenes are synthetic equivalents of dienes due to their ability to be converted by a concerted ring-opening process into conjugated 1,3-dienes, which can be trapped by a dienophile.…”

Section: Introductionmentioning

confidence: 99%

Ruthenium‐Catalyzed Synthesis of Alkylidenecyclobutenes via Head‐to‐Head Dimerization of Propargylic Alcohols and Cyclobutadiene–Ruthenium Intermediates

Paih

Dérien

Demerseman

et al. 2005

Chemistry A European J

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The reaction of propargylic alcohols with carboxylic acid, or phenol derivatives, in the presence of the precatalyst [RuCl(cod)(C5Me5)] leads selectively to a variety of alkylidenecyclobutenes through head-to-head dimerization of propargylic alcohol. The first step is the formation of a cyclobutadiene-ruthenium intermediate resulting from the head-to-head coupling of two molecules of propargylic alcohol. On protonation with strong acids (HPF6, HBF4) dehydration of the cyclobutadiene complex leads to formation of an alkylidenecyclobutenyl-ruthenium complex. The X-ray structure of one such complex, [RuCl(C5Me5)(eta4-R'CCH--CH--C=CR2)] (R'=cyclohexen-1-yl, CR2 = cyclohexylidene) has been determined. Carboxylate is added at the less substituted carbon of the cyclic allylic ligand. DFT/B3 LYP calculations confirm that the intermediate arising from head-to-head coupling of alkyne to the RuClCp* species yields the cyclobutadiene-ruthenium complex more easily with propargylic alcohol than with acetylene.

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Conversion of Nitriles into Tertiary Amines: N,N‐Dimethylhomoveratrylamine

2003

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Conversion of nitriles into tertiary amines: N,N‐dimethylhomoveratrylamine intermediate: 2‐(3,4‐Dimethoxyphenyl)‐N,N‐dimethylacetamidine product: N,N‐dimethylhomoveratrylamine product: CH 3 CH 2 NH(CH 2 ) 5 CH 3 product: CH 3 CH 2 NHCH 2 C 6 H 5

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Squaraine chemistry. Synthesis, characterization, and optical properties of a class of novel unsymmetrical squaraines: [4-(dimethylamino)phenyl](4'-methoxyphenyl)squaraine and its derivatives

Cited by 114 publications

References 0 publications

Squaraine chemistry. A new approach to symmetrical and unsymmetrical photoconductive squaraines. Characterization and solid state properties of these materials

Squaraine chemistry. A new approach to symmetrical and unsymmetrical photoconductive squaraines. Characterization and solid state properties of these materials

Ruthenium‐Catalyzed Synthesis of Alkylidenecyclobutenes via Head‐to‐Head Dimerization of Propargylic Alcohols and Cyclobutadiene–Ruthenium Intermediates

Conversion of Nitriles into Tertiary Amines: N,N‐Dimethylhomoveratrylamine

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