Yavuz Taskesenligil

Programmed instruction revisited: a study on teaching stereochemistry

This study is aimed at comparing the success of programmed instruction with the conventional teaching approach on teaching stereochemistry, and whether gender has any effect on student success. Forty chemistry teacher trainees attending the same class in the Department of Chemistry Education in a large state university in eastern Turkey were the subjects of the study. Of the forty trainees twenty were selected as the experimental group and the other twenty as the control group. The study was implemented in a total of sixteen lecture hours (each 50 min) in four weeks (four lecture hours per week). The subject, stereochemistry in organic chemistry, was taught to the experimental group by the researcher through ‘programmed instruction’ and the control group was taught by the course lecturer through traditional teaching. The data collection tools were: Stereochemistry Achievement Test (SAT), programmed stages (frames), and the views of the students. An ANCOVA (Analysis of Co-Variance) showed that there was a statistically significant difference between programmed instruction and conventional teaching approach on the success level of students’ learning in stereochemistry. In addition, it was found that female students were more successful than their male counterparts in the experimental group. The findings suggest that programmed learning could be considered as a better alternative to conventional lecturing in teaching stereochemistry. [Chem. Educ. Res. Pract., 2006, 7 (1), 13-21]

Insecticidal Metabolites from the Rhizomes of Veratrum album against Adults of Colorado Potato Beetle, Leptinotarsa decemlineata

The dried rhizomes of Veratrum album were individually extracted with CHCl3, acetone, and NH4OH/benzene to test the toxic effects against the Colorado potato beetle, Leptinotarsa decemlineata, which is an important agricultural pest. Fifteen compounds in various amounts were isolated from the extracts using column and thin‐layer chromatography. The chemical structures of 14 compounds were characterized as octacosan‐1‐ol (1), β‐sitosterol (2), stearic acid (3), diosgenin (4), resveratrol (5), wittifuran X (6), oxyresveratrol (7), β‐sitosterol 3‐O‐β‐D‐glucopyranoside (8), diosgenin 3‐O‐α‐L‐rhamnopyranosyl‐(1→2)‐β‐D‐glucopyronoside (9), oxyresveratrol 3‐O‐β‐D‐glucopyranoside (10), jervine (11), pseudojervine (13), 5,6‐dihydro‐1‐hydroxyjervine (14), and saccharose (15) using UV, IR, MS, 1H‐ and 13C‐NMR, and 2D‐NMR spectroscopic methods. However, the chemical structure of 12, an oligosaccharide, has not fully been elucidated. Compounds 4, 6, 9, and 10 were isolated from V. album rhizomes for the first time in the current study. The toxic effects of three extracts (acetone, CHCl3, and NH4OH/benzene) and six metabolites, 2, 2+4, 5, 7, 8, and 11, were evaluated against the Colorado potato beetle. The assay revealed that all three extracts, and compounds 7, 8, and 11 exhibited potent toxic effects against this pest. This is the first report on the evaluation of the toxic effects of the extracts and secondary metabolites of V. album rhizomes against L. decemlineata. Based on these results, it can be concluded that the extracts can be used as natural insecticides.

An unusual thioketal formation: Attempted synthesis of 2,3-dibromo-6,7-benzobicyclo[3.2.1]octa-2, 6-diene

Abstract Treatment of 8 with 2 equiv. of NBS gave terra bromide 9 which was converted to the corresponding unsaturated ketone 7. Reaction of 7 with 1,2-ethanedithiol produced the unusual thioketal 14 besides normal ketalization product 13. Reduction of 13 with Raney nickel resulted in the formation of hydrocarbon 17, instead of the expected dibromide 4.

Evidence for the intermediacy of an alkyne rather than an allene in the base-induced reaction of 3-bromo-6,7-benzobicyclo[3.2.1]octa-2,6-diene

Abstract In order to reveal the real intermediate in the base-promoted reaction of 1 , 2-methyl derivative 16 has been synthesized and its HBr elimination reaction studied. Reaction of 16 with potassium t -butoxide did not form the corresponding allene intermediate 17 under the same reaction conditions as described for 1 . Under more drastic conditions exocyclic diene 18 was formed. These results provide evidence for the intermediacy of the alkyne 3 in the base-promoted reaction of 1 .

Türkiyede Fen Eğitiminde Kullanılan Ölçme Araçları Betimsel İçerik Analizi

Bu calismayla fen egitimi alaninda gelistirilen ve Turk kulturune uyarlanan olceklerde ve basari testlerinde yazarlarin yogunlastigi alanlari, arastirmalarda tercih edilen konulari, arastirma metodunu, orneklemi ve verilerin analizinde tercih edilen veri analiz yontemini, sonuc da ise gelistirilen/uyarlama yapilan araci belirlemek amaclanmistir. Bu amacla 2002-2013 yillari arasinda 21 farkli ulusal dergide yayimlanmis fen egitimi alaninda gelistirilen/uyarlanan olceklerden/basari testlerinden olusan toplam 62 makalenin dokuman incelemesi yapilmistir. Gelistirilen/uyarlanan olceklerde ve basari testlerinde daha cok fen ve teknoloji alaninda yapilan calismalarin agirlik kazandigi, orneklem grubu olarak lisans ve ortaogretim ogrencileriyle ve orneklem buyuklugu olarak ise 101-200 araligindaki orneklem buyuklukleriyle calismalarin yapildigi anlasilmaktadir. Ayrica daha cok ogrencilerin tutumlarini belirlemeye yonelik olceklerin gelistirildigi gorulmektedir. Gelistirilen/adaptasyon calismasi yapilan olceklerin buyuk bir cogunlugunda acimlayici faktor analizinin (%74) tercih edildigi, cok az calismada ise dogrulayici faktor analizinin (%4) uygulandigi gorulmektedir

3,7-Diphenyl-5,6;10,11-dibenzotricyclo[7.2.1.03,8]dodeca-5,7,10-trien-4-one

3,7-Diphenyl-5,6;10,11-dibenzotricyclo[7.2.1.0 3,8 ]dodeca-5,7,10-trien-4-one consists of a fused ring system containing four six-membered rings and a five-membered ring with two pendant phenyl groups. The four phenyl rings are planar while the cyclohexadienone ring exbits a flattened 1,3-diplanar conformation