Basri Atasoy

A concise synthesis of the 2,3-dimethylene-1,4-methano-1,2,3,4-tetrahydronaphthalene and its reaction with singlet oxygen

Abstract Palladium-catalyzed carbomethoxylation of benzonorbornadiene (7) yielded dimethyl-1,4-methano-1,2,3,4-tetrahydronaphthalene-2,3-dicarboxylate (9) which was transformed in three steps into 2,3-dimethylene-1,4-methano-1,2,3,4-tetrahydronaphthalene (4) in a high yield. Reaction of 4 with singlet oxygen resulted in the formation of epoxy-endoperoxide (12). X- ray crystallographic analysis demonstrated that epoxide ring is exo as methylene bridge. For the first time, the epoxy-endoperoxide formation from the “one pot” reaction of a diene with singlet oxygen was observed. The epoxy-endoperoxide formation mechanism was discussed. CoTPP (Cobalt( II )tetraphenylporphyrin) catalyzed rearrangement of epoxy-endoperoxide gave hydroxy-aldehyde (13) which was oxidized into dialdehyde (14).

The Effect of a Conceptual Change Approach on Understanding of Students' Chemical Equilibrium Concepts.

The purpose of this study was to compare the effects of a conceptual change approach over traditional instruction on tenth‐grade students’ conceptual achievement in understanding chemical equilibrium. The study was conducted in two classes of the same teacher with participation of a total of 44 tenth‐grade students. In this study, a pre‐test/post‐test control group semi‐experimental design pattern was used. During teaching the topic of chemical equilibrium concepts in the chemistry curriculum, a conceptual change approach was applied in the experimental group whereas traditional instruction was followed in the control group. Data were analysed with an independent samples t‐test, and an analysis of covariance using the pre‐test scores as the covariate. The results showed that the conceptual change approach was statistically more effective than traditional instruction in terms of students’ conceptual understanding. After the six‐week intervention, interviews were conducted with 18 selected students in the study. In the interviews a prevailing alternative conception was detected beside many alternative conceptions. When they were asked to compare equilibrium constants of two different reactions they mostly responded to mean that ‘the bigger the mol number of the products, the bigger the equilibrium constant’ without considering what proportions the reactants were transformed into products in a reaction. Also, in this study a two‐tier multiple choice test was developed related to chemical equilibrium to detect students’ concepts and alternative concepts.

Synthesis of 3,4-disubstituted furans via unsaturated cyclic peroxides arising by photooxygenation of 2,3-bis (bromomethyl)-1,3-butadiene and derived exocyclic dienes

Abstract The reaction of 2,3-bis (bromomethyl)-1,3-butadiene (3) with singlet oxygen resulted in the formation of a peroxide (4) which rearanged with CoTPP to bis(bromomethyl)furan. Zinc-induced debromination of cycloadducts which were obtained from the [2+4] Diels-Alder reactions of 3 with DMAD and benzyne gave exocyclic dienes 7 and 11 from which fused ring furans were prepared by photooxygenation followed by rearrangement. 4,5-Dimethylene-1,2-dioxane (14) was synthesized by zinc-induced debromination of 4. The cycloaddition reactions of 14 with MTAD, singlet oxygen and DMAD were studied.

4,5-Dimethylene -1,2-dioxane and derived Diels-Alder adducts

Abstract 4,5-Dimethylene-1,2-dioxane (1) was prepared by zinc-induced debromination of 4,5-bis (bromomethyl)-1,2-dioxacylohexa-4-en (4) obtained from 2,3-bis (bromomethyl-1,3-butadiene (3) by reaction with singlet oxygen. Diels-Alder additions of 1 with singlet oxygen, dimethyl acetylenedicar☐ylate and N-methyl-1,2,4-triazoline-3,5-dione gave adducts 2,6 and 8 respectively. 3,4-Disubtituted furans 5 and 9 were obtained from peroxides 4 and 8 by cobalt (II) tetraphenylporphyrin catalyzed rearrangement.

Rearrangement of unsaturated cyclic peroxides obtained by photooxygenation of 2,3-dimethylene-7-oxabenzonorbornene and 2,3-dimethylene-1,4-etheno-1,2,3,4-tetrahydronaphthalene

Abstract Cobalt(II) tetraphenylporphyrin (CoTPP)-catalyzed rearrangement of peroxide 11 obtained by the photooxygenation of 5 gave a mixture of epoxides 15 (or 16) and 17. However, CoTPP-catalyzed rearrangement of peroxide 20 arising by photooxygenation of 2,3-dimethylene-1,4-etheno-1,2,3,4-tetrahydronaphthalane 6 gave 1,4-etheno-1,2,3,4-tetrahydronaphtho[b]-furan 21. The different behaviour of these endoperoxides 11 and 20 is discussed in terms of ring strain and the degree of the pyramidalization of the CC bond.

BİLİMSEL YARATICILIĞI DESTEKLEYEN ÖĞRETİMİN MADDELERİN AYRILMASI KONUSUNDAKİ ÖĞRENCİ ÇİZİMLERİNE ETKİSİ

Ogrencilerin kimyayi ogrenmelerinde, maddenin submikroskobik duzeydeki yapisiyla ilgili uygun imgelere sahip olmalari esastir. Submikroskobik duzeyle ilgili imgeleme; yeterli onbilginin yaninda, bu duzey algilanamadigindan hayal gucunu de gerekli kilar. Hayal gucu ise literaturde yaraticiligin kapsaminda ele alinmistir. Bilissel psikoloji alaninda yapilan calismalar imgelerin niteligi ile yaratici dusunme arasinda zayif-orta siddette iliski oldugunu ortaya koymaktadir. Bu calismada, ogrencilerin maddelerin ayrilmasi konusunda submikroskobik duzeyle ilgili imgelerini yansitan cizimlerinin ayrintiligina, bilimsel yaraticiligi destekleyen ogretimin etkisi incelendi. Arastirma, 9. sinifta ogrenim goren 57 ogrenci ile gerceklestirildi. Arastirma yontemi olarak, yari deneysel desen kullanildi. Arastirmada, katilimcilarin onbilgileri ve bilimsel yaraticiliklari kontrol altina alindiginda, bilimsel modele uygun ayrintilar iceren cizimler yapmalarinda, bilimsel yaraticiligi destekleyen ogretimin, geleneksel ogretimden daha etkili oldugu belirlendi.