Preparation of ω-Hydroxy Acids by Reduction of α,ω-Methylene Diesters with NaBH<sub>4</sub>

Benitez, Pilar; Delgado, Ana; Farrera, Joan‐Anton; Ribó, Josep M.

doi:10.1080/00397919708004080

Cited by 6 publications

(8 citation statements)

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“…Mesobiliverdin XIII methylene diester (5) [3], mesobiliverdin XIII propane-1,3-diyl diester (6) [3], and mesoprotoporphyrin IX methylene diester (7) [4] were obtained as previously described. Physical and chemical data of these substances have already been reported [3,4]. Other data not yet published are described in the text (ROESY, CD, UV/Vis; Tables 1±3, Fig.…”

Section: Methodsmentioning

confidence: 99%

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Solution Structure of Mesobiliverdin XIIIα Bridged Between the Propionic Acid Substituents [1]

Crusats

Delgado

Farrera

et al. 1998

Monatshefte fuer Chemie

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The solution structure of two intramolecular diesters (methylene and 1,3-propylidene) of mesobiliverdin-XIII was studied and compared with that of the corresponding dimethyl ester. The UV/Vis absorption spectra, chiral discrimination with ethyl (S)-(À)-lactate, and the 1 H NMR spectra (ROESY) show that the cyclization of the propionate substituents of biliverdins does not signi®cantly affect the helix structure or its (P) (M) interconversion. The internal methylene diester does not show conformational heterogeneity of the propionate substituents and probably exists only in one diastereomeric form. In this case, the results point to a simultaneous racemization of the tetrapyrrole helix and the bridge cycle. The methylene diester of mesoprotoporphyrin was also synthesized. In this case, the geometry of the propionate chains is probably similar to that present in some hemoproteins. Zur Struktur des u È ber die Propionsa Èurereste u È berbru È ckten Mesobiliverdins XIII in Lo ÈsungZusammenfassung. Die Struktur zweier zyklischer Ester (Methylendioxy-und 1,3-Dipropylenoxy-) des Mesobiliverdin XIII in Lo Èsung wurde untersucht und mit der des entsprechenden Dimethylesters verglichen. Die UV/Vis-Spektren, die chirale Diskriminierung mit A È thyl-(S)-(À)-Laktat und die 1 H-NMR-Spektren (ROESY) zeigen, daû durch interne Zyklisierung u Èber die Propionsa Èure die Helixstruktur oder die (P) (M) Konvertierung kaum bein¯uût wird. Beim zyklischen Methylendioxyester weisen die Propionsa Èuresubstituenten verschiedene Konformationen auf. Wahrscheinlich existiert nur eine einzige diastereoisomere Form unter gleichzeitiger Racemisierung der Tetrapyrrolhelix und des Ringes der Bru Èckenester. Der Methylendioxyester des Mesoprotoporphyrins wurde ebenfalls dargestellt. Die Geometrie seiner Propionatreste entspricht wahrscheinlich derjenigen, die in einigen Ha Èmoproteinen gefunden wurde.

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Section: Methodsmentioning

confidence: 99%

“…Recently it has been shown that the same cyclization process can also be performed in the case of porphyrins [4].…”

Section: Introductionmentioning

confidence: 99%

Solution Structure of Mesobiliverdin XIIIα Bridged Between the Propionic Acid Substituents [1]

Crusats

Delgado

Farrera

et al. 1998

Monatshefte fuer Chemie

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“…8) give hydroxyacids upon reduction with NaBH 4 and the corresponding methylene diester (5) cannot be obtained [4]. This is probably due to the inductive effect of the two methylenic a In memory of Francesc R. Trull who dedicated many years of his life to bilirubin chemistry Ã Corresponding author oxygens on the carbonyl groups [5]. However, this partial reduction could also be a consequence of a strong torsional effect exerted by the bridge.…”

Section: Introductionmentioning

confidence: 89%

“…These results demonstrate that the smaller cycle of the methylene diester affects the structure in the solution of the bilirubin derivative in a similar degree to the propan-1,3-diyl ester. Furthermore, this shows that the methylene bilirubin diesters cannot be obtained by reduction of the corresponding biliverdins [4,5] because of the activating effect exerted by the methylene oxygen on the carbonyl group and not to torsional energy effects which could affect the addition of nucleophiles at C10.…”

Section: Visible Spectra Of Cyclized Bilirubinoids (Biliverdin Bisulfmentioning

confidence: 99%

Solution Structure of Mesobilirubin XIIIa Bridged Between the Propionic Acid Substituents [1]

Crusats

Delgado

Farrera

et al. 1998

Monatshefte fuer Chemie

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The effect of cyclization of the propionic acid residues in mesobilirubin XIII propan-1,3-diyl ester on the angle between the dipyrrinone halves has been studied. This compound is shown to dimerize in chloroform solutions, and a conformation is proposed which is similar to that of the corresponding dimethyl ester. The results point to the contribution of %±% interactions, besides hydrogen bonding, to the geometry of the dimer.

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“…Unlike the homogeneous catalysts, the heterogeneous catalysts have some advantages such as longer operation of catalyst, easy separation of catalyst from the sodium meta-borate (NaBO 2 ) solution, and there is no formation of other byproducts apart from NaBO 2 during the process Benitez et al, 1997;Isha et al, 2012;). Among these catalysts, the Co-B is a good candidate for hydrogen generation owing to its high activity and low cost (Krishann et al, 2009;Ozdemir et al, 2013;Coskuner et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Effect of Co-B Catalyst Synthesized in Methanol on the Hydrolysis of Sodium Borohydride

İzgi̇¹,

Şahi̇n²,

Onat³

et al. 2017

jist

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In this study, the effect of parameters such as treatment time, temperature, amount of catalyst and the NaBH 4 concentration were investigated on the catalytic activity of Co-B catalyst synthesized in methanol and the optimum conditions were determined. The maximum hydrogen generation rate was found as 2200 mLH 2 / min.g.catalyst for Co-B catalyst synthesized in methanol while 600 mLH 2 /min.g.catalyst was found for Co-B catalyst synthesized in water. The activation energy was found as 34.694 kJ /mol for Co-B catalyst prepared in methanol. Consequently, our results suggest that the cold plasma treatment with different conditions can be used as a promising technique to enhance the catalytic activity of Co-B catalyst prepared in the methanol.Keywords: Co-B catalyst, cold plasma treatment, methanol, sodium borohydride.ÖZET: Bu çalışmada, metanol içinde sentezlenen Co-B katalizörünün etkinliğini arttırmak için alternatif bir yöntem olarak soğuk bir plazma yöntemi seçilmiştir. Işlem süresi, sıcaklık, katalizör miktarı ve NaBH 4 konsantrasyonları gibi parametrelerin Co-B katalizörün katalitik aktivitesi üzerindeki etkisi araştırılmış ve optimum koşullar belirlenmiştir. Maksimum hidrojen üretim oranı, metanolde sentezlenen Co-B katalizörü için 2200 mLH 2 / min.g.katalizör olarak bulunurken, suda sentezlenen Co-B katalizörü için 600 mLH 2 /min.g. katalizör olarak bulunmuştur. Metanolde hazırlanan Co-B katalizörü için aktivasyon enerjisi 34.694 kJ/mol olarak belirlenmiştir. Sonuç olarak, sonuçlarımız, farklı koşullardaki soğuk plazma işleminin, metanolde hazırlanan Co-B katalizörünün katalitik aktivitesini arttırmak için umut verici bir teknik olarak kullanılabileceğini göstermektedir.Anahtar Kelimeler: Co-B katalizörü, soğuk plazma işlemi, methanol, sodyum borhidrür.

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Preparation of ω-Hydroxy Acids by Reduction of α,ω-Methylene Diesters with NaBH₄

Cited by 6 publications

References 6 publications

Solution Structure of Mesobiliverdin XIIIα Bridged Between the Propionic Acid Substituents [1]

Solution Structure of Mesobiliverdin XIIIα Bridged Between the Propionic Acid Substituents [1]

Solution Structure of Mesobilirubin XIIIa Bridged Between the Propionic Acid Substituents [1]

Effect of Co-B Catalyst Synthesized in Methanol on the Hydrolysis of Sodium Borohydride

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Preparation of ω-Hydroxy Acids by Reduction of α,ω-Methylene Diesters with NaBH4

Cited by 6 publications

References 6 publications

Solution Structure of Mesobiliverdin XIIIα Bridged Between the Propionic Acid Substituents [1]

Solution Structure of Mesobiliverdin XIIIα Bridged Between the Propionic Acid Substituents [1]

Solution Structure of Mesobilirubin XIIIa Bridged Between the Propionic Acid Substituents [1]

Effect of Co-B Catalyst Synthesized in Methanol on the Hydrolysis of Sodium Borohydride

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Preparation of ω-Hydroxy Acids by Reduction of α,ω-Methylene Diesters with NaBH₄