Alfa-pinen ve dibromokarbenden sentezlenen geminaldibromosiklopropan halkasının açılma reaksiyon mekanizmasının incelenmesi
Küçük Resim Yok
Tarih
2000
Yazarlar
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Dergi ISSN
Cilt Başlığı
Yayıncı
Trakya Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
ÖZET 2,6,6-Trimetilbisiklo[3,l,l]hept-2-en (a-pinen) [1] ve dibromokarbenden 2,7,7- trimetil-3,3-dibromo-trisiklo[4,l,l,02,4]oktan [2] sentezlendi ve oluşan bu ürünün farklı ortamlarda açılmasıyla dört ürün elde edildi. [1] [2] Dibrom bileşiği [2] nin; a) kloroform içerisinde; oda sıcaklığında, 60-65°C ta, hafif asidik ortamda b) metilen klorür içerisinde trietilamin ve pridin ile açılmasından iki farklı ürün 3-bromo-7,7- dimetil-2-metilenbisiklo[4,l,l]okt-3en [3] ve 3-bromo 2,7,7-trimetil-bisiklo[4,l,l]-2,4- oktadien [4] elde edildi. [3] [4] c) Geminal dibromosiklopropan halkasmın sulu asetonda açılmasıyla dört farklı ürün elde edildi. Bunların ikisi kloroform ve metilenklorür içerisinde açılanlarla aynı olan ürünler [3] ve [4], diğer ikisi ise 3-bromo-2,7,7-trimetilbisiklo[4.1.1]okt-3-en-2-ol [5] ve 2-(4-bromo-5- metilsiklohepta-3,5-dien-l-il) propan-2-ol [6] dur.[5] [61. Karben reaksiyonunda reaksiyona girmeyen a-pinenin kloroformda geminal dibromo- siklopropan halkasınm açılması esnasmda açığa çıkan HBr ile katılma tepkimesi vermesi sonucu oluştuğu tahmin edilen 2-bromo-l,7,7-trimetilbisiklo[2.2.1]heptan [7] elde edildi ve bu bileşiğin oluşumu oc-pinenden HBr geçirilerek doğrulandı. m Yapılan bu işlemler sonucunda elde edilen toplam altı ürün saflaştmlarak gerekli spektrumlar alındı ve geminaldibromosiklopropan halkası için uygun açılma mekanizması önerildi. Bu çalışmalar sonucunda literatürde bu yöntemle elde edilmeyen iki yeni bileşik (5 ve 6) karakterize edildi. Zekir ŞENOL 15/09/2000
SUMMARY An investigation Of The Mechanism Of The Opening Reactions Of Geminal Dibromocyclopropane Ring Synthesized From a-Pinene And Dibromocarbene. 2,7,7-trimethyl-3,3-dibromo-tricyclo[4,l,l,02'4]octane [2] was synthesized by the reaction of 2,6,6-trimethylbicyclo-[3,l,l]hept-2-en (a-pinene) [1] with dibromocarbene, and four different products were obtained by ring opening of this product [1] at several different reaction conditions. [1] [2] i) in chloroform; at room temperature, at 60-65 °C, slightly acidic medium; ii) in methylene chloride; with triethylamine and pyridine, geminal dibromoyclopropane ring was opened and two different products, 3-bromo-7,7-dimethyl-2-methylenebicyclo[4,l,l] oct- 3-en [3] and 3-bromo-2,7,7-trimethylbicyclo[4,l,l]-2,4-octadiene [4], were obtained at different ratios. [3] [4] iii) Four different products were isolated by opening of geminal dibromocyclopropane ring in aqueous acetone solution. First two of these products were the same with those obtained in chloroform and methylene chloride, i.e., [3] and [4]. The remaining two products were 3- bromo-2,7,7-trimethylbicyclo[4.1.1]oct-3-en-2-ol [5] and 2-(4-bromo-5- methylcyclohepta- 3,5-dien 1-yl) propan-2-ol [6][5] [6] In the carbene reaction, the unreacted a-pinene interacted with HBr, which evolved during the opening reaction of geminaldibromocyclopropane in the chloroform; so that an addition reaction occured yielding 2-bromo-l,7,7-trimethylbicyclo[2.2.1]heptane [7]. This structure is confirmed by passing gaseous HBr through a-pinene solution. m Zekir ŞENOL 15/09/2000
SUMMARY An investigation Of The Mechanism Of The Opening Reactions Of Geminal Dibromocyclopropane Ring Synthesized From a-Pinene And Dibromocarbene. 2,7,7-trimethyl-3,3-dibromo-tricyclo[4,l,l,02'4]octane [2] was synthesized by the reaction of 2,6,6-trimethylbicyclo-[3,l,l]hept-2-en (a-pinene) [1] with dibromocarbene, and four different products were obtained by ring opening of this product [1] at several different reaction conditions. [1] [2] i) in chloroform; at room temperature, at 60-65 °C, slightly acidic medium; ii) in methylene chloride; with triethylamine and pyridine, geminal dibromoyclopropane ring was opened and two different products, 3-bromo-7,7-dimethyl-2-methylenebicyclo[4,l,l] oct- 3-en [3] and 3-bromo-2,7,7-trimethylbicyclo[4,l,l]-2,4-octadiene [4], were obtained at different ratios. [3] [4] iii) Four different products were isolated by opening of geminal dibromocyclopropane ring in aqueous acetone solution. First two of these products were the same with those obtained in chloroform and methylene chloride, i.e., [3] and [4]. The remaining two products were 3- bromo-2,7,7-trimethylbicyclo[4.1.1]oct-3-en-2-ol [5] and 2-(4-bromo-5- methylcyclohepta- 3,5-dien 1-yl) propan-2-ol [6][5] [6] In the carbene reaction, the unreacted a-pinene interacted with HBr, which evolved during the opening reaction of geminaldibromocyclopropane in the chloroform; so that an addition reaction occured yielding 2-bromo-l,7,7-trimethylbicyclo[2.2.1]heptane [7]. This structure is confirmed by passing gaseous HBr through a-pinene solution. m Zekir ŞENOL 15/09/2000
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Anahtar Kelimeler
Kimya, Chemistry
