Yeni dioxepin türevlerinin sentezi(III)

Abstract

Kozmetik ve polimer gibi çok çeşitli endüstri kollarında kullanım alanı bulabilen, kaplamacılık ve yapıştırıcı üretiminde de büyük rol oynayan l,3-dioxepin bileşikleri ve bunların türev lerini sentez etmek için çalışmalar süregelmektedir. Bu çalışmada, cis-2-buten-l,4-diol ile çeşitli keton, alde hit yada asetaller reaksiyona sokularak yeni l,3-dioxepin türev leri sentez lenmeye çalışılmıştır. Piperonal, 3,4-dihidroksibenzaldehit, hidratrop aldehit, fe- nil asetaldehi t, süksinik semialdehit, siklopentenon, l»4-sik- lohekza dion mono etilen ketal, PTSA katalizörlüğünde çözücülU or tamda Dean-Stark aparatında cis-diol ile reaksiyona sokulmuş ve reaksiyonların oluşup, oluşmadığı incelenmiştir. Genellikle cis- diol fazlasında çalışılmıştır. Ayrıca sitral dimetil asetal ve N,N-bis-2,2-dietoksietil metil amin yine asit katalizörlüğünde cis- diol ile damıtma sisteminde reaksiyona sokularak transasetalleşme reaksiyonu gerçekleştirilmeye çalışılmıştır. Gerçekleştirilen reaksiyonların yürüyüşü Gaz-Likit Kromotog- rafisi ve înce Tabaka Kromqtografisi ile izlenmiş ve oluşan ürün lerin saflaştırı İmasında zaman zaman Preparati f-TLC tekniğinden yararlanılmıştır. Saflaştırılan ürünlerin tanımlanması İR, 'H-MMR ve Î3C-NMR spektrumları ile yapılmıştır. Ayrıca bütün bileşikler kütle spektrumları çekilmek üzere ingiltere'ye gönderilmiştir. Şüphesiz ki kütle spektrumlarıda yapıların aydınlatılmasında önem li rol oynayacaktır. Çalışmada elde edilen tüm ürünler orijinal dir.

1,3-Dioxepins have many industrial applications such as; serving starting materials for organic reactions, producing modi fied polymers, synthesis of parfumes and so on. In the pharmaceu tical, phytopharmaceutical, fragrance, lacquer and polymer indus tries they are used both as intermediates and as end products. Generally 1,3-dioxepins are synthesized from the reaction between cis-2-buten-l,4-diol and an aldehyde, ketones or their derivatives. Reactions used in the synthesis are either acetali zation or transacetalization reactions. Both acetalization reac tions are equilibrium reactions. The acetal formed from the ace talization reaction can easily hydrolyze in the aqueous acidic medium. That's why water formed during the reaction must be re moved to prevent hydrolysis. NC = 0 + ( ) ^ " II + HoO < T In the transacetalization reaction alkoxy-exchange occurs between an acetal and an alcohol through the formation of the mixed acetal. This reaction can be called as alcohol interchange. Equilibrium can be shifted to the right by using a large excess of alcohol which is reactant and by distilling off the alcohol formed. H* RK /°R4 \/ C. + 2R3-0H /\ R2 0R4 According to the mechanism of the acetalization reaction only one mol of water is produced from one mol of carbonyl compound. However, VII two moles of alcohol forms in the transacetalization reaction '1\ C = 0 OH OH,C = OH- vl I - OH + OH OH R /OH C H+ R V *. \ / C - R. / -H20 R r; V. 2 Dean-Stark apparatus was used to remove water by azeotropic distillation while distillation system was used to remove alcohol. Second carbon atom of 1,3-dioxepin plays an important role in the configuration, and in the physical and chemical structures. Changing of the substituents on the second carbon atom, cause dif ferent physical and chemical properties. In this study, some aldehydes, ketones and acetals were reacted with cis-2-buten-l,4-diol in acidic medium to prepare new 1,3-dioxepin derivatives. vm Piperonal and cis-diol were reacted using Dean-Stark appara tus in the acidic medium. The reaction product was white crystal line compound which had a w.p. of 53°. However in the literature, it was a liquid (b.p. 133°C/7 mm Hg, Hg (n)25=1.5585). To prove the structure, IR and'.1H-NMR techniques were used and it was seen that, the compound obtained, in this study was an expected product. To prepare the bromine derivative of the piperonal acetal, bromi nation reaction was carried out using Br2/CCİ4 at room tempe rature. But, the reaction was not achived under this conditions. It is interesting to note that the acetal hydrolized to aldehiyde (piperonal) during the bromi nation although the reaction medium was not acidic. In the reaction of cyclopenten-1-one with cis-2-buten-l,4- diol yield was \iery low. This was an expected result because, cyclopenten-1-one gives different products, depending on the reac tion conditions such as strong or weak acidic medium. Because of low conversion, P-TLC was used for the isolation of 1,3-dioxepin derivative. From the İH-NMR spectrum it was seen that two main products were produced. One of them was the expected acetal, the other was an enol-ether derivative of cyclopenten-1-one. When 3, 4-di hydroxy benzaldehyde was reacted with cis-2-buten- 1,4-diol, the product formed at low yield. This was also an expec ted situation because di hydroxy aromatic compounds are easily oxi- dizable compounds. In the preperation of an acetal from hydratrop aldehyde (2- phenyl propanal) and cis-2-buten-l,4-diol, yield was very high. Vacuum distillation was used for the purification of product. Boiling point was 145-148°C at 10 mm Hg. The structure of product was determined from their IR and 13C-NMR spectra. Since phenyl acetaldehyde is an easily polymerizable com pound, it is found as solution in the different solvents. Here the solvent was diethyl-phytalate (50%). Although the reaction was achived and yield was very high, product could not be identi fied by IR data because of sharp phytalate peaks. TLC and GLC techniques were used to identify the product formation. » In the reaction of succinic semialdehyde with cis-2-buten- 1,4-diol, two types of reactions could be possible, one was the acetal ization reaction the other was the esteri f i cation and ace- talization reactions together since reaction was carried out using excess of cis-diol. The two kind of products, could be formed. From IR and ^H-NMR spectra and TLC anlysis it was noticed that only one type of product was obtained, which undergone both ix both acetalization and esteri fi cation. 1,4-Cyclohexanedione mono ethylene ketal was reacted with cis-2-buten-l,4-diol for synthesis of 1,3-dioxepin derivative. Reaction product was white crystalline compound which had a melting point of 132-134°C. From the IR and 1H-NMR spectra, it was obvi ously seen that product had no dioxy ethylenic function. This means that both acetalization and transacetalization reactions occured together. Since, in the reaction of N,N-bis-2,2-diethoxyethylmethyl amin and cis-2-buten-l,4-diol, the reactants were used in the same mol ratio (1/1), only one 1,3-dioxepin ring was obtained. If the excess of the diols was used, it could be possible to prepare the compound which has two 1,3-dioxepin rings. When citral-dimethyl acetal was used as a reactant, the reac tion products were p-cymene and an etheric compound which were ob tained because of the cyclization reaction of the citral-dimethyl acetal in the acidic media.. The reactants and products were given in table 1. All of the products were posted to England to be taken their mass spectra. It's obvious that mass spectra will also play an important role. to identify the structures. All products are origi nal compounds. They mi ght be used as starting materials in flavour, fragrance, cosmetic, pharmaceutic and polymer industries. Table- 1 Reaction products of the cis-2-buten-l,4-diol and carbonyl compounds used in this study. Reactants Products Piperonal 0 Cvclopentene-1-one HO HO /' 3, 4-Di hydroxy benzaldehyde CH3-CH- Ç // V Hydratrop aldehyde '/ W CR, - cf 0 H Phenyl acetaldehyde 0 0 / CH9 // 0 HO HO 0' / 0 CH3~CH -QH H CH X 2 0 CH = CH I CH.J I OH xi Table-! Reaction products of the cis-2-buten-l,4-diol and carbonyl compounds used in this study.