http://nopr.niscair.res.in/handle/123456789/4527 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/4559 Title: Effect of structure of diamide-diimide-diamines based on L-methionine on curing behaviour and thermal stability of DGEBA <br/> <br/>Authors: Darshan; Malhotra, Priti; Narula, A K <br/> <br/>Abstract: <smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="metricconverter"> New L-methionine-based diacids containing imide units are synthesized <i>via</i> reaction of dianhydride (PMDA/ODA/NTDA) with L-methionine in the presence of a mixture of acetic acid and pyridine (3:2 v/v). A series of diamide-diimide-diamines (DADIDAS) was synthesized by activation of obtained diacids with thionyl chloride (SOCl₂) and then condensation with excess of different aromatic diamines containing ether, methylene and sulfone units <i>via </i>high temperature condensation method. The DADIDAS prepared by reacting PMDA/NTDA/ODA with L-methionine (M) followed by condensation with 4<b>,</b>4'-diaminodiphenyether (E)/ 4,4'-diaminodiphenylmethane (M) and 4,4'-diaminodiphenyl sul­fone (S) have been designated as PME, PMM, PMS, NME, NMM, NMS, OME, OMM and OMS. The diamide-diimide-diamines were examined by FT-IR, ¹H and ¹³C NMR spectro­scopy and elemental analysis. The curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) with aromatic diamide-diimide-diamines was studied by Differential Scanning Calorimetry (DSC). The peak exotherm temperature (T_P) was lowest in DGEBA cured using PMM and highest in DGEBA cured using NMS. Thermal stability of the isothermally cured DGEBA with diamide-diimide-diamines was investigated using dynamic thermogravimetry analysis (TGA) in nitrogen atmosphere and it was found that NTDA based diamide-diimide-diamines provide good stability to DGEBA. Char yield was found to be highest in the case of EOMM. </smarttagtype> <br/> <br/>Page(s): 893-903 Fri, 29 May 2009 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/4558 Title: Indium trichloride: a versatile catalyst for the synthesis of fully saturated imidazoles <br/> <br/>Authors: Kidwai, Mazaahir; Priya; Poddar, Roona; Singhal, Kavita <br/> <br/>Abstract: Ketimines are readily reduced to corresponding vicinal diamines using InCl₃ and zinc followed by simple cyclization to fully saturated imidazoles with various aldehydes. InCl₃has been found to play an efficient catalytic role for this methodology to give high yields in short time. Moreover effect of different promoters and Lewis acids are also studied. <br/> <br/>Page(s): 886-892 Fri, 29 May 2009 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/4557 Title: Solvent free Stobbe condensation: A green approach <br/> <br/>Authors: Banerjee, Shubhra; Tayde, Ravibabu A; Sharma, Bhagyashree D <br/> <br/>Abstract: <smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="metricconverter"> Solvent free Stobbe-condensation of methyl <img src='/image/spc_char/beta.gif'> benzoyl propionate <b>1c</b> and methyl <img src='/image/spc_char/beta.gif'>-naphthoyl propionate <b>1d</b> with benzaldehyde, anisaldehyde and furfural using dry solid potassium tertiary butoxide at room temperature and at 80°C gives <img src='/image/spc_char/beta.gif'> arylidene <img src='/image/spc_char/beta.gif'> benzoyl propionic acid <b>2a-c</b> and <img src='/image/spc_char/beta.gif'> arylidene <img src='/image/spc_char/beta.gif'> naphthoyl propionic acid <b>2d-f</b> respectively. Base-catalysed solvent free Stobbe condensation of dimethyl succinate <b>1e</b> and aliphatic and aromatic ketones at room temperature gives 1,1-alkylidene monomethyl succinate <b>3a,b</b> and 1,1-arylidene monomethyl succinate <b>3c</b> respectively. </smarttagtype> <br/> <br/>Page(s): 882-885 Fri, 29 May 2009 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/4556 Title: 2-(2-Alkylamino-4-aminothiazol-5-oyl)-N-methylbenzimidazoles: Synthesis and the effect of intra molecular H-bonding in ¹H NMR <br/> <br/>Authors: Reji, T F Abbs Fen; Rajasekharan, K N <br/> <br/>Abstract: 2-(2-Alkylamino-4-aminothiazol-5-oyl)-N-methylbenzimi­da­zoles, as the analogs of the cytotoxic marine alkaloid dendrodoine, is synthesized and characterized by elemental analysis, IR, NMR and mass spectral data. The thiourea derivatives provide four ring atoms for the thiazole ring construction and thus act as [C-N-C-S] synthons. The remaining carbon of the thiazole is sourced from 2-(2-bromoacetyl)-N-methylbenzimidazole. This [4+1] heterocyclization reaction is adopted for the synthesis of novel benzimidazole derivatives. The presence of two signals in the ¹H NMR spectrum arising from the NH₂ hydrogens shows that the two hydrogens are not exchanging rapidly on the chemical shift time scale and they are in two different chemical environments due to H-bonding. <br/> <br/>Page(s): 877-881 Fri, 29 May 2009 22:58:59 GMT