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Sintesis N'-Benzilidena-2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetohidrazida
No full textSenyawa 2H-kromen-2-on atau kumarin merupakan senyawa heterosiklik yang mengandung satu atom oksigen dan beserta turunannya menunjukkan aktivitas biologis yang beragam. Senyawa 7-hidroksi-4-metil-2H-kromen-2-on 6 dengan kerangka kumarin juga memiliki aktivitas antivirus terhadap hepatitis B, infeksi virus hepatitis C, dan HIV serta telah digunakan dalam penanganan penyakit alzheimer. Modifikasi struktur 7-hidroksi-4-metil-2H-kromen-2-on 6 dapat dilakukan melalui alkilasi dan hidroksilasi pada posisi C4 dan C7 dan dilaporkan dapat meningkatkan aktivitas biologi. Penelitian yang dilakukan bertujuan untuk mendapatkan N’-benzilidena-2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetohidrazida 1 melalui modifikasi 7-hidroksi-4-metil-2H-kromen-2-on 6 melalui alkilasi, insersi amina, dan substitusi benzaldehida. Penelitian dilakukan melalui sintesis 7-hidroksi-4-metil-2H-kromen-2-on 6, etil 2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetat 4, dan 2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetohidrazida 2 yang dilanjutkan dengan reaksi pembentukan senyawa benzilidena. Penelitian yang dilakukan telah berhasil mendapatkan 7-hidroksi-4-metil-2H-kromen-2-on 6 dengan rendemen 63,82% melalui reaksi antara resorcinol 8 dalam etil asetoasetat 9. Etil 2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetat 4 dengan rendemen 57,40% telah diperoleh melalui alkilasi 7-hidroksi-4-metil-2H-kromen-2-on 6 dengan etil kloroasetat 7 dalam suasana basa (penambahan K2CO3). Selanjutnya, 2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetohidrazida 2 dengan rendemen 94,86% diperoleh melalui reaksi etil 2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetat 4 dengan hidrazin hidrat 5. Akhirnya, N’-benzilidena-2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetohidrazida 1 dengan rendemen 79,23% telah berhasil diperoleh melalui reaksi 2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetohidrazida 2 dengan benzaldehida 3 dalam suasana asam.
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The 2H-chromen-2-one or coumarin compound is a heterocyclic compound containing one atom of oxygen and its derivatives show various biological activities. The 7-hydroxy-4-methyl-2H-chromen-2-one 6 compound with a coumarin framework also has antiviral activity against hepatitis B, hepatitis C virus infection, and HIV and has been used in the treatment of Alzheimer's disease. Modification of the 7-hydroxy-4-methyl-2H-chromen-2-one 6 structure can be carried out through alkylation and hydroxylation at the C4 and C7 positions and is reported to increase biological activity. The aim of the research was to obtain N'-benzylidene-2-((4-methyl-2-oxo-2H-chromen-7-yl)-oxy)acetohydrazide 1 through modification of 7-hydroxy-4-methyl-2H-chromen-2-one 6 via alkylation, amine insertion, and benzaldehyde substitution. The research was carried out through the synthesis of 7-hydroxy-4-methyl-2H�chromen-2-one 6, ethyl 2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetate 4, and ethyl 2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetohydrazide 2 followed by the reaction to form a benzylidene compound. The research has succeeded in obtaining 7-hydroxy-4-methyl-2H-chromen-2-one 6 with a yield of 63.82% through the reaction between resorcinol 8 in ethyl acetoacetate 9. Ethyl 2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetate 4 in a yield of 57.40% was obtained by alkylation of 7-hydroxy-4-methyl-2H-chromen-2-one 6 with ethyl chloroacetate 7 in alkaline conditions (addition of K2CO3). Furthermore, 2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetohydrazide 2 with a yield of 94.86% was obtained through the reaction of ethyl 2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetate 4 with hydrazine hydrate 5. Finally, N'-benzylidene-2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetohydrazide 1 with yield 79.23% was successfully obtained by the reaction of 2-((4-methyl-2-oxo-2H-chromen-7- yl)oxy)acetohydrazide 2 with benzaldehyde 3 in an acidic conditions
Sintesis Senyawa Hidrazon Berbasis Trans-sinamaldehida Dan Para-metoksisinamaldehida
No full textSenyawa hidrazon dengan gugus azometin (‒NHN=CH‒) yang terikat pada cincin aril dapat diperoleh melalui reaksi kondensasi antara aldehida aromatik dengan amina primer. Penelitian ini melaporkan sintesis senyawa hidrazon 1a-d dan 2a-e berbasis trans-sinamaldehida dan para-metoksisinamaldehida. Sintesis senyawa hidrazon berbasis trans-sinamaldehida dilakukan antara trans-sinamaldehida 3 dengan fenil hidrazin 5, asam 2-tiofenakarboksilat hidrazida 6, asam 4-piridinkarboksilat hidrazida 7, dan 2-((4-metil-2-okso-2H-kromen-7-il)oksi)asetohidrazida 8. Sedangkan sintesis senyawa hidrazon berbasis para-metoksisinamaldehida dilakukan antara para-metoksisinamaldehida 4 dengan hidrazida 5-8 dan 2-(4-formil-2-etoksifenoksi)asetohidrazida 9. Senyawa hidrazon berbasis trans-sinamaldehida yang diperoleh berupa 1-fenil-2-(3-fenilalillidena)hidrazin 1a, N-(3-fenilalilidena)tiofena-2-karbohidrazida 1b, N-(3-fenilalilidena)isonikotinohidrazida 1c, dan 2-((4-metil-2-okso-dihidro-2H-kromen-7-il)oksi)-N’-(3-fenilalilidena)asetohidrazida 1d masing-masing diperoleh dengan yield 31,65%, 74,74%, 52,85%, dan 90,38%. Lebih lanjut, senyawa hidrazon berbasis para-metoksisinamaldehida yang didapatkan adalah 3-(4-metoksifenil)-alilidena-2-fenilhidrazin 2a, N'-(3-(4-metoksifenil)alilidena)tiofena-2-karbo-hidrazida 2b, N'-(3-(4-metoksi-fenil)alilidena)isonikotinohidrazida 2c, N'-(3-(4-metoksifenil)alilidena)-2-((4-metil-2-okso-dihidro-2H-kromen-7-il)oksi)aseto-hidrazida 2d, dan 2-(4-formil-2-metoksifenoksi)-N'-(3-(4-metoksifenil)alilidena)-asetohidrazida 2e dengan yield masing-masing sebesar 35,94%, 47,54%, 83,28%, 87,74%, 93,34%. Senyawa hasil sintesis diuji kemurnian dengan KLT sistem tiga eluen, KLT dua dimensi, dan uji titik leleh. Struktur seluruh senyawa hasil sintesis diidentifikasi dengan spektroskopi FTIR dan NMR serta analisis LCMS-MS.
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Hydrazone compounds with an azomethine group (‒NHN=CH‒) attached to the aryl ring can be obtained through a condensation reaction between heated aldehyde and primary amine. This study reports the synthesis of hydrazone compounds 1a-d and 2a-e based on trans-cinnamaldehyde and para-methoxycinnamaldehyde. Synthesis of trans-cinnamaldehyde-based hydrazone compounds was carried out between trans-cinnamaldehyde 3 with phenyl hydrazine 5, 2-thiophenecarboxylic acid hydrazide 6, 4-pyridinecarboxylic acid hydrazide 7, and 2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetohydrazide 8. Meanwhile, the synthesis of hydrazone-based compounds para-methoxynamaldehyde is carried out between para-methoxynamaldehyde 4 with hydrazide 5-8 and 2-(4-formyl-2-methoxyphenoxy)acetohydrazide 9. The trans-cinnamaldehyde based hydrazone compound obtained is 1-phenyl-2-(3-phenylalylidene)hydrazine 1a, N-(3-phenylallylidene)thiophene-2-carbohydrazide 1b, N-(3-phenylallylidene)isonicotinohydrazide 1c, and 2-((4-methyl-2-oxo-dihydro-2H-chromen-7-yl)oxy)-N'-(3-phenylallylidene)acetohydrazide 1d was respectively obtained by yield 31.65%, 74.74%, 52.85%, and 90.38%. Furthermore, the para-methoxynamaldehyde based hydrazone compounds obtained were 3-(4-methoxyphenyl)allylidene-2-phenylhydrazine 2a, N'-(3-(4-methoxyphenyl)allyl-idene)thiophene-2-carbohydrazide 2b, N'-(3-(4-methoxy-phenyl)allylidene)iso-nicotinohydrazide 2c, N'-(3-(4-methoxyphenyl)allylidene)-2-((4-methyl-2-oxo-dihydro-2H-chromen-7-yl)oxy)acetohydrazide 2d, and 2-(4-formyl-2-methoxy-phenoxy)-N'-(3-(4-methoxyphenyl)allylidene)acetohydrazide 2e with a respective yield of 35.94%, 47.54%, 83.28%, 87.74%, 93.34%. The purity of the synthesized compounds was tested using three-eluent TLC system, two-dimensional TLC, and melting point test. The structures of all synthesized compounds were identified using FTIR and NMR spectroscopy as well as LCMS-MS analysis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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