Loading...
Search for:
ketones
0.007 seconds
Total 81 records
Solvent-free synthesis of 3-benzylpyrano[3,2-c]pyran/chromene-2,5-diones via tandem reaction of 4-hydroxy-6-methyl-pyran-2-one and 4-hydroxycoumarin with Baylis-Hillman adduct acetates
, Article Scientia Iranica ; Vol. 21, issue. 3 , 2014 , p. 735-741 ; 1026-3098 ; 2345-3605 ; Koushki Foroushani, B ; Lotfi Kalahroodi, E ; Sharif University of Technology
Abstract
4-hydroxycoumarin 2a and 4-hydroxy-6-methyl-pyran-2-one 2b were applied in a one-pot reaction with Baylis-Hillman adduct acetates 1 to form novel 3-benzylpyrano [3, 2-c] pyran-2, 5-diones 3 in high yields (70-85%). The synthesized framework is available in many biologically active moieties. The reaction was carried out under different conditions to achieve optimum conditions. The results indicated that Et3N, as a base under solvent-free conditions, was optimum. The reaction procedure and purification method are mild and straightforward
Nanoscale graphene oxide sheets as highly efficient carbocatalysts in green oxidation of benzylic alcohols and aromatic aldehydes
, Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 38, Issue 4 , 2017 , Pages 745-757 ; 02539837 (ISSN) ; Heidari, M ; Akhavan, O ; Sharif University of Technology
Science Press
2017
Abstract
Nanoscale graphene oxide (NGO) sheets were synthesized and used as carbocatalysts for effective oxidation of benzylic alcohols and aromatic aldehydes. For oxidation of alcohols in the presence of H2O2 at 80 °C, the NGOs (20% mass fraction) as carbocatalysts showed selectivity toward aldehyde. The rate and yield of this reaction strongly depended on the nature of substituents on the alcohol. For 4-nitrobenzyl alcohol, <10% of it was converted into the corresponding carboxylic acid after 24 h. By contrast, 4-methoxybenzyl alcohol and diphenylmethanol were completely converted into the corresponding carboxylic acid and ketone after only 9 and 3 h, respectively. The conversion rates for...
A simple method for detecting the possible changes of hidden information of watermarked image in an MMS message
, Article IEEE- International Symposium on Biometrics and Security Technologies, ISBAST'08, Islamabad, 23 April 2008 through 24 April 2008 ; 2008 ; Sharif University of Technology
2008
Abstract
After expanding the use of computer and its affect on different aspect of life, the copyright issue has gained many attractions. For this purpose watermarking methods are proposed. In these methods a code is embedded into digital material that can be used to approve ownership, it can be visible or invisible to the user. On the other hand with the rapid growth of mobile phones, mobile telecommunication companies starting to add additional features to their mobile phones such as MMS (Multimedia Messaging Service) in order to attract more customers. MMS is a technology that allows mobile phones sending messages that includes multimedia objects esp. images. For copyright protection of images...
Towards a model for inferring trust in heterogeneous social networks
, Article 2nd Asia International Conference on Modelling and Simulation, AMS 2008, Kuala Lumpur, 13 May 2008 through 15 May 2008 ; 2008 , Pages 52-58 ; 9780769531366 (ISBN) ; Habibi, J ; Sayyadi, M ; Sharif University of Technology
2008
Abstract
People usually use trust and reputation to cope with uncertainty which exists in the nature and routines. The existing approaches for inferring trust rely on homogeneous relations. In other words, trust is just inferred by a homogeneous relation. In this paper, we present a new model for inferring trust using heterogeneous social networks; we use relation extraction to make a trust relation from the other relation such as friendship and the college relation and then introduced an algorithm to infer trust using extracted relation. In order to get higher performance, we extend relation extraction problem by proposing a genetic algorithm. This algorithm is more scalable, interpretable and...
A new achievable rate for relay networks based on parallel relaying
, Article 2008 IEEE International Symposium on Information Theory, ISIT 2008, Toronto, ON, 6 July 2008 through 11 July 2008 ; 2008 , Pages 1328-1332 ; 21578101 (ISSN) ; 9781424422579 (ISBN) ; Aref, M. R ; Sharif University of Technology
2008
Abstract
In this paper, we propose a new concept of relaying named parallel relaying to obtain a new achievable rate for relay networks. The proposed encoding scheme is based on partial decoding, where the relay decodes only part of the transmitted message. The superiority of our proposed method to the previous ones is that, it can be applied to the relay networks with general structure, not necessarily with feed-forward structure. The proposed achievable rate is also used to establish the capacity of a class of semi-deterministic relay network which is a generalization of Aref network. © 2008 IEEE
A new method for design cycle period management in aircraft design process
, Article Aircraft Engineering and Aerospace Technology ; Volume 80, Issue 5 , 5 September , 2008 , Pages 497-509 ; 00022667 (ISSN) ; Malaek, S. M ; Sharif University of Technology
2008
Abstract
Purpose - The purpose of this paper is to present research into reducing the aircraft design cycle period, by reducing the necessary number of design cycle iterations. The design cycle period is one of the main characteristics of the design process and design cycle iterations play a major role in the design cycle period. Design/methodology/approach - Toachieve the above-mentioned goal, the paper presents a mathematical model of iterations for the aircraft design process. This model describes the design coupled tasks as a discrete-linear time invariant dynamic system. This model also helps identify tasks which are the most important for generating iterations. This new method basically helps...
Analysis of communication systems using iterative methods based on Banach's contraction principle
, Article 2007 6th International Conference on Information, Communications and Signal Processing, ICICS, Singapore, 10 December 2007 through 13 December 2007 ; 2007 ; 1424409837 (ISBN); 9781424409839 (ISBN) ; Saberian, M. J ; Akhaee, M. A ; Nasiri Mahallati, R ; Marvasti, F ; Sharif University of Technology
2007
Abstract
In this paper, the application of a well known mathematical theorem, Banach's fixed point theorem [1], is investigated in iterative signal processing in communications. In most practical communication systems some sort of a contraction mapping is used to enhance the operation of the system. Thus, using a suitable iterative approach, one can set the system in its fixed point and hence, the distortion produced in the transmitter, channel and the receiver can be compensated. In other words, a loosely designed transceiver can be enhanced by an iterative method. In order to verify the truth of the proposed iterative method, the distortion of A/D and D/A converters is compensated at the receiver....
Extension of linear isotherm regularity to long chain primary, secondary and tertiary alcohols, ketones and 1-carboxylic acids by group contribution method
, Article Fluid Phase Equilibria ; Volume 234, Issue 1-2 , 2005 , Pages 11-21 ; 03783812 (ISSN) ; Kalantar, Z ; Sharif University of Technology
2005
Abstract
In this work, the group contribution approach has been used in combination with the linear isotherm regularity (LIR) equation of state to estimate pvT properties of primary, secondary and tertiary alcohols, ketones and 1-carboxylic acid. In addition, the isothermal compressibility and thermal expansion coefficient of these compounds have been predicted. We assume each of these organic compounds as a hypothetical mixture of methyl, methylene and a functional group, in which the interaction potential of each pair is assumed to be the average effective pair potential. Then, the LIR equation of state (EOS) has been extended to such a hypothetical mixture. Three basic compounds, namely propane,...
Oxidation of aldehydes and ketones into carboxylic acids and esters using 4-amino-2-chloroperbenzoic acid supported on silica gel
, Article Synthetic Communications ; Volume 35, Issue 8 , 2005 , Pages 1103-1107 ; 00397911 (ISSN) ; Ghazanfari, D ; Ahmadibeni, Y ; Karimi Jaberi, Z ; Ezabadi, A ; Sharif University of Technology
2005
Abstract
4-Amino-2-chloroperbenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of aldehydes and ketones to the corresponding carboxylic acids and esters. Copyright © Taylor & Francis, Inc
Oxidative deprotection of silylethers, acetals and ketals by oxygen or air in presence of manganese and cobalt salts of 4-aminobenzoic acid supported on silica gel as catalyst
, Article Synthetic Communications ; Volume 30, Issue 10 , 2000 , Pages 1857-1863 ; 00397911 (ISSN) ; Kalantari, F ; Sharif University of Technology
Marcel Dekker Inc
2000
Abstract
Oxidative deprotection of silylethers, acetals and ketals, to their corresponding alcohols, aldehydes and ketones have been achieved using oxygen or air in the presence of cobalt and manganese salts of 4-aminobenzoic acid supported an silica gel as catalysts. Reactions are clean and catalysts can be recovered easily and reused repeatedly
Optimization of cervical cage and analysis of its base material: A finite element study
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 236, Issue 11 , 2022 , Pages 1613-1625 ; 09544119 (ISSN) ; Abollfathi, N ; Khajehzhadeh, M ; Hassani Gangaraj, M ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
Nowadays, cervical disorders are common due to human lifestyles. Accordingly, the cage design should be optimized as an essential issue. For an optimal design, an objective function is utilized to calculate the proper geometrical parameters. Additionally, the base material of the cage plays a key role in its functionality and final cost. Novel materials are currently introduced with more compatibility with the bone in terms of mechanical and chemical properties. In this study, a cervical cage was modeled based on PEEK material with three types of tooth designs on its surface. The cervical cage is assumed to be implanted between C6 and C7 vertebrae. The geometric parameters of the cage were...
Fabrication and Characterization of Modified Polyether Ether Ketone/Carbon Nanofiber Nanocomposite for Bone Application
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor)
Abstract
The use of polyether ether ketone (PEEK) in bone implants is limited due to a lack of cell adhesion and proliferation. Therefore, in this study, we modified the surface of PEEK with a nanocomposite coating containing piezoelectric and bioactive properties. Sulfonated PEEK with suitable mechanical and hydrophilic properties along with polyvinylidene fluoride was used as a biocompatible polymer with piezoelectric properties for coating. Also, nanohydroxyapatite was used as a bioactive material, and carbon nanofibers with significant mechanical and electrical properties were used in the nanocomposite. The surface was sulfonated as an intermediate layer to improve the connection between the...
Facile synthesis of highly substituted 2-pyrone derivatives via a tandem Knoevenagel condensation/lactonization reaction of β-formyl-esters and 1,3-cyclohexadiones
, Article Tetrahedron Letters ; Vol. 55, issue. 18 , April , 2014 , p. 2908-2911 ; ISSN: 00404039 ; Mirjafary, Z ; Javan, M. J ; Motamen, S ; Saeidian, H ; Sharif University of Technology
Abstract
A mild and efficient tandem process for the synthesis of new highly substituted 2-pyrones starting from commercially available 2-arylacetic acids has been developed. The synthesis is based on the Knoevenagel condensation of 1,3-cyclohexadiones with various β-formyl-esters, followed by lactonization in the presence of nano ZnO (20 mol %). Moderate to high yields and readily available cheap starting materials are the key features of the present method
Commercial zinc oxide: a facile, efficient, and eco-friendly catalyst for the one-pot three-component synthesis of multisubstituted 2-aminothiophenes via the Gewald reaction
, Article Industrial and Engineering Chemistry Research ; Volume 51, Issue 44 , October , 2012 , Pages 14577-14582 ; 08885885 (ISSN) ; Ahmadi, S. J ; Rezaei Seresht, E ; Javadi, F ; Yasemi, M. A ; Hosseinpour, M ; Maleki, B ; Sharif University of Technology
2012
Abstract
An eco-friendly, simple, and effective protocol is developed for the synthesis of various multisubstituted 2-aminothiophenes. In the presence of a catalytic amount of ZnO (5 mol), ketones or aldehydes, malononitrile and elemental sulfur were converted to the corresponding 2-aminothiophene derivatives in moderate to high yields (27%-70%) under solvent-free conditions at 100 °C. Zinc oxide as an efficient, readily available, and reusable catalyst, showed very good catalytic activity for the synthesis of 2-aminothiophene derivatives. Thus far, little research has been reported on the Gewald reaction under solvent-free conditions; to the best of our knowledge, this is the first time that it has...
A green procedure for direct oxidation of organic halides to aldehydes and ketones catalyzed by a molybdate-based catalyst
, Article New Journal of Chemistry ; Volume 39, Issue 5 , Feb , 2015 , Pages 3845-3851 ; 11440546 (ISSN) ; Shakourian Fard, M ; Ramezanpour, S ; Mahmoodi Hashemi, M ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
A molybdate-based heterogeneous magnetic catalyst was synthesized and used in direct oxidation of various primary and secondary organic halides to the corresponding aldehydes and ketones using 30% H2 O2 as an oxidant in ethanol. Various organic halides were oxidized to their corresponding aldehydes and ketones in good to excellent yields. The catalyst system can be easily separated by applying an external magnetic field and reused for 6 runs without any significant loss of catalytic activity. The catalyst was fully characterized by FT-IR, SEM, TEM, EDS, XRD, VSM, ICP-AES techniques, and elemental analysis (CHN)
Application of a free volume model in correlating thermodynamic properties of β-lactam, tetracycline, fluoroquinolone and chloramphenicol antibiotic groups in associating fluids
, Article Chemical Engineering Research and Design ; Volume 87, Issue 3 , 2009 , Pages 335-342 ; 02638762 (ISSN) ; Taghikhani, V ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
2009
Abstract
In this work, an expression for the free volume Gibbs energy model based on the local composition concept (LCC) has been proposed in correlating the solubility, the partitioning and the surface tension of β-lactam, tetracycline, fluoroquinolone and chloramphenicol antibiotic groups in water, alcohol, ketone, trihalomethane, ether and ester solvent groups. Similar to the LCC models the proposed model has two combinatorial and residual terms. The extended Guggenheim model is used as combinatorial term and a new local composition-based model, which is the extended local area fraction NRTL-NRF model, is proposed for the residual term. The results obtained from the proposed model have been...
A heterogeneous strong basic nanocrystalline copper(II) oxide catalyst for efficient synthesis of 4-keto-4,5,6,7-tetrahydrobenzofurans
, Article Catalysis Communications ; Volume 10, Issue 10 , 2009 , Pages 1423-1426 ; 15667367 (ISSN) ; Sadjadi, S ; Hosseinpour, M ; Outokesh, M ; Hekmatshoar, R ; Sharif University of Technology
2009
Abstract
An efficient synthesis of tetrahydrobenzofurans is carried out in one pot through the reaction of 1,3-diketone and phenacyl bromides compound using a heterogeneous basic nano particles copper oxide catalyst. The protocol offers advantages in terms of higher yields, short reaction times, and mild reaction conditions, with reusability of the catalyst. © 2009 Elsevier B.V. All rights reserved
Synthesis of fulvene vinyl ethers by gold catalysis
, Article Chemistry - A European Journal ; Volume 26, Issue 23 , 2020 , Pages 5280-5287 ; Schwarz, J ; Lustosa, D. M ; Pourkaveh, R ; Hoffmann, M ; Rominger, F ; Rudolph, M ; Dreuw, A ; Hashmi, A. S. K ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
Gold-catalyzed cyclization of 1,5-diynes with ketones as reagents and solvent provides diversely substituted vinyl ethers under mild conditions. The regioselectivity of such gold-catalyzed cyclizations is usually controlled by the scaffold of the diyne. Herein, we report the first solvent-controlled switching of regioselectivity from a 6-endo-dig- to 5-endo-dig-cyclization in these transformations, providing fulvene derivatives. With respect to the functional-group tolerance, aryl fluorides, chlorides, bromides, and ethers are tolerated. Furthermore, the mechanism and selectivity are put to scrutiny by experimental studies and a thermodynamic analysis of the product. Additionally,...
One-to-one and one-to-many node-disjoint routing algorithms for WK-recursive networks
, Article Proceedings of the International Symposium on Parallel Architectures, Algorithms and Networks, I-SPAN, 7 May 2008 through 9 May 2008, Sydney, NSW ; 2008 , Pages 227-232 ; 9780769531250 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
2008
Abstract
Recently, routing with disjoint paths has received much attention to provide more performance and fault tolerance. On the other hand, WK-recursive mesh network has been studied extensively due to its favorable properties such as high degree of stability and resilience. The connectivity of a network is an important measure of fault tolerance, while the diameter represents the worst-case transmission delay between two arbitrary nodes. In this paper, we propose one-to-one and one-to-many disjoint routings mechanisms for WK-recursive mesh networks to further exhibit the performance and fault tolerance of such networks. © 2008 IEEE
Bioconjugation of interferon-alpha molecules to lysine-capped gold nanoparticles for further drug delivery applications
, Article Journal of Dispersion Science and Technology ; Volume 29, Issue 8 , 2008 , Pages 1062-1065 ; 01932691 (ISSN) ; Vossoughi, M ; Almzadeh, I ; Zeinali, M ; Sharif University of Technology
2008
Abstract
Gold nanoparticles are potentially very attractive components for therapeutic delivery since they can be synthesized with any diameter from 1 to 200 nm to carry a payload of therapeutic molecules into a cell without triggering an immune response. Gold nanoparticles must undergo surface transformations before coupling to therapeutic molecules to become eligible for this purpose. It is now more understood that amine groups can bind to gold nanoparticles strongly, which has enabled surface modification of gold nanoparticles with amino acid lysine through its amine group. These lysine capped gold nanoparticles can further be coupled to therapeutic molecules for delivery purposes. In this study...