Subsitue fenilglioksallerin sentezi ve reaksiyonları

Abstract

Bu çalışmada bir a-dikarbonil bileşiği olan fenilglioksal ve türevlerinin 2-naftol ve rezorsinol ile asidik ortamdaki reaksiyonları incelenmiştir. Başlangıç bileşiği olan fenilglioksal ve türevleri, asetofenon ve türevlerinin SeOa ile oksidasyonuyla hazırlanmıştır. Fenilglioksal ve türevleri 2-naftol ile dioksepin türevlerini vermişlerdir. Reaksiyon kondenzasyon aşaması sonrası asetalleşme yerine fenil halkası ile bir halka kapanması ile yürümüştür. Fenilglioksal türevlerinin molekül içi asetalleşme yapmayıp, fenil halkası ile eter ler lesme reaksiyonuna gitmesi hacimsal olarak daha küçük bir fenol ik bileşiğin nasıl davranacağı sorusunu getirmiş ve bu nedenle reaksiyonlar rezorsinol ile tekrarlanmıştır. Aynı bileşikler rezorsinol ile benzofuran türevi vermişlerdir. Reaksiyon kondenzasyon aşaması sonrası yarı asetalleşme ve su ayrılması ile furaıı halkasının oluşumu şeklinde gerçekleşmiştir. Bir 0-ketoaldehit olan benzoilasetal dehit 2-naftol ve rezorsinol ile farklı ürünler vermiştir. 2-naftol ile bir benzopiran yapısı oluşmuştur. Reaksiyon kondenzasyon sonrası molekül içi yarı asetalleşme ve su eliminasyonu ile tamamlanmıştır. Rezorsinol ile kondenzasyon sonrası tam asetalleşme ile dibenzodioksosin türevi oluşmuştur. Sonuç olarak rezorsinol ' ün yarı asetalleşme reaksiyonu verdiği durumlarda 2-naftol hiç asetalleşme vermemiş» rezorsinol ' ün asetalleşme verdiği reaksiyonlarda 2-naftol hemiasetal vermiştir. Elde edilen ürünlerin yapıları TLC, İR» '.H-NMR ve MASS analiz yöntemleriyle aydınlatılmaya çalışılmıştır.

In order to synthesize the substitute phenylglgoxal four methods were used. First method was oxidation of w-bromo acetophenon by dimethyl sulfoxide. I v O C -CH2Br +CH3SOCH3 Second method was convert ion of ketal nitrates to corresponding dicarbonly derivatives, under the influence of sodiumacetate in Dimethylsulf oxide at 20-25 °C. Third method was the reaction w-bromo acetophenon with morpholine.. . 0. . o x-<0)-C -CH2Br +H/ O-^x-^^S-C -CH2 -/ \) HC1 fZZTK OH Fourht method was selenium oxdidation of corresponding acetophenones. '^H- CII3 +502 -CH-OH + Se + H70 II I ' 0 Ah VI 1 Among the four method, the best way for synthesize the phenylglyoxal derivatives was the fourth method, the yield was better than the others. All of the starting materials were shown below. The obtained phenylglyoxals were reacted with 2-naphthol in acidic media, and the resulting products were characterized with FT-IR, 1H-NMR and Mass spectra. From p-methoxyphenyl glyoxal and p-chlorophenyl glyoxal, the dioxepin type compounds were produced. 2,4-dimethoxy phenylglyoxal gave product mixtures. The suggested mechanism leading to these products was shown below. As seen in scheme 1, the first step of the reaction was the condensation reaction of two moles of 2-napthol and phenylglyoxal. Structure (A) was in enol form due to the effect of three aromatic rings. So intramolecular acetal ization could not occured. Instead, -OH group of napthol ring attached to the phenyl ring and dioxepin derivative formed. Similarly, same starting compounds were reacted with resorsinol to see the effect of ring size on the reaction. From the spectral data, the structure of the products were detected as benzofuran derivatives. The reaction mechanism consisted of three steps; condensation, hemiacetal ization and water elemination. While 2-naphthol was not given any acetal ic reaction, resorsinol gave hemiacetal ic structure because of the smaller ring size. The similar reactions were considered for the viii benzdylacetaldehyde. In benzoylacetaldehyde there is a methylen group between two carbonyl groups. Benzoylacetaldehyde was prepared by the reaction of ethylformat and acetophenone. This reaction was known Claisen condensation. At the end of the reaction sodium salt of the (J- ketoaldehyde was formed. Ihen it was converted to acidic form before the reaction with phenolic compounds. IX c=o 6=0 O O OH 'OH H-» HO. O ı i-o OH OH K1 -H20 W 9 HO-C-0 HO- /PjV- CH- (Pj)- 0H OH <0hrcH3' H"°^0C2Hs ^O-? eNa+ II -CH-C-H 0 ÜTI" Claisen prcxiuct was reacted with 2-naphthol in acidic medium. From the spectral data, it was seen as naphthopyran type compound. Reaction mechanism was similar to the phenylglyoxal-resorsinol reaction. i. e, condensation, hemiacetalization and water elimination. x Benzoylalataldehyde was also reacted with resorcinol using p-toluensulfonic acid as catalyst. Different from the 2-naphthol, resorsinol gave intra-molecular acetalization reaction, and dibenzo dioxocin type compound formed. OH + HO ^ 'oh c=0 OH 0H - " sv As a result, when resorsinol gave the hemiacetal reaction, 2- naphthol couldn't give any acetalic structure. When resorsinol gave acetalic structure 2-napthol formed hemiacetal. These results were deduced to the ring size of aromatic rings.