Comparative kinetic studies on the alkaline hydrolysis of halogen substituted isocoumarins

H. Badaruddin AHMAD; M. Aslam MALANA; Muhammad YOUSAF

Makale detayları

Comparative kinetic studies on the alkaline hydrolysis of halogen substituted isocoumarins

Yazarlar:

H. Badaruddin AHMAD | M. Aslam MALANA | Muhammad YOUSAF

Yayıncı:

TUBITAK

Dergi:

Turkish Journal of Chemistry 2010 Vol.34 Issue 3, pp.381-386

Belge Tipi:

Makale

Yayın Tarihi:

2/2010

Belge Dili:

Türkçe

Document ID (Org No.):

2000728055

Sıklık:

İki Aylık

eISSN:

1303-6130

pISSN:

1300-0527

Özet:

 

Kinetics of the hydrolysis of 3-(2'-chloro-6'-fluorobenzyl)  isocoumarin (1), 3-(4'-fluorophenyl)isocoumarin (3), 3-(2'-  fluorophenyl)isocoumarin (5), 3-(2'-chlorophenyl)isocoumarin (7), and  3-(4'-chlorophenyl)isocoumarin (9) were studied spectrophotometrically  in the presence of aqueous solution of potassium hydroxide.  The rates  of hydrolyses for these isocoumarins were compared.  The data for  isocoumarin (1) were further investigated to probe the reaction  mechanism.  The dependence of pseudo-first order rate constant kobs  on hydroxide ion concentration is fitted by the expression kobs =  ko + k1[OH] + k2 [OH]2, showing the formation of monoanionic and  dianionic tetrahedral intermediates during the course of reaction.  The magnitude of ko shows significant participation of solvent in the  reaction mechanism.

 

Kinetics of the hydrolysis of 3-(2'-chloro-6'-fluorobenzyl)  isocoumarin (1), 3-(4'-fluorophenyl)isocoumarin (3), 3-(2'-  fluorophenyl)isocoumarin (5), 3-(2'-chlorophenyl)isocoumarin (7), and  3-(4'-chlorophenyl)isocoumarin (9) were studied spectrophotometrically  in the presence of aqueous solution of potassium hydroxide.  The rates  of hydrolyses for these isocoumarins were compared.  The data for  isocoumarin (1) were further investigated to probe the reaction  mechanism.  The dependence of pseudo-first order rate constant kobs  on hydroxide ion concentration is fitted by the expression kobs =  ko + k1[OH] + k2 [OH]2, showing the formation of monoanionic and  dianionic tetrahedral intermediates during the course of reaction.  The magnitude of ko shows significant participation of solvent in the  reaction mechanism.

Makale detayları

Comparative kinetic studies on the alkaline hydrolysis of halogen substituted isocoumarins

Yazarlar: H. Badaruddin AHMAD | M. Aslam MALANA | Muhammad YOUSAF

Yayıncı: TUBITAK

Dergi: Turkish Journal of Chemistry 2010 Vol.34 Issue 3, pp.381-386

Belge Tipi: Makale

Yayın Tarihi: 2/2010

Belge Dili: Türkçe

Document ID (Org No.): 2000728055

Sıklık: İki Aylık

eISSN: 1303-6130

pISSN: 1300-0527

Sayı

Yazarlar:

H. Badaruddin AHMAD | M. Aslam MALANA | Muhammad YOUSAF

Yayıncı:

TUBITAK

Dergi:

Turkish Journal of Chemistry 2010 Vol.34 Issue 3, pp.381-386

Belge Tipi:

Makale

Yayın Tarihi:

2/2010

Belge Dili:

Türkçe

Document ID (Org No.):

2000728055

Sıklık:

İki Aylık

eISSN:

1303-6130

pISSN:

1300-0527