Some new mono isoimides of asymmetrical pyromillitdiimide derived from pyromellitic dianhydride were synthesized and studied by their melting points, FTIR, and 1HNMR spectroscopy and CHN analysis (for some of them) and it was proved that the mechanism of the formation of these isoimides followed, the mechanism suggested by Cotter et al. by using N, N─-dicyclohexylcarbodiimide as dehydrating agent, in spite of the groups attached to the phenyl moiety as mentioned in literatures.

   The new Schiff bases derived from pyromellitic dianhydride were   synthesized  by  several  steps  reaction . A symmetrical  diamic acide  [I ]a-c  were  synthesized  by  the  reaction  of  pyromellitic  dianhydride  with  some aromatic  amines  (containing  electron  withdrawing , repulling  groups ) in dry acetone.      In the second step the  diacids were converted  to  their corresponding  diimide [II ]a-c using acetic anhydride and sodium acetate system as a dehydrating agent,    via  the  intra molecular  cyclization  steps&nbs

This work involves the synthesis and characterization of asymmetrical pyromellitdiimide
derivatives [IV]a-f
by four sequence steps selective reaction . One mole of pyromellitic dianhydride
was reacted with one mole of various primary aromatic amines [ 4-nitro aniline , 4-chloro aniline , 4-toludine and 4-anisidine] in excess of dry acetone to produce six compounds (N-substituted-pyromellitamic monoacid) [I]a-f . These new compounds [I]a-d were converted to the corresponding
N- substituted- pyromellitmonoimide [II]a-d via their heating at (80-90)
0
C in sodium acetate-acetic
anhydride mixture .
The compounds [II]a-f
were allowed to react with one mole of another primary amines in
excess of dry acetone t

  In this work two moles of 2-amino benzothiazole were allowed to react with one mole of pyromellitic dianhydride to produce N,N‾-Bis-(benzathiazol-2-yl) pyromellitamic diacid [I] which was submitted to esterification via the reaction with dimethyl sulphate in sodium carbonate in acetone as a solvent to synthesize N,N‾-bis-(benzothiazol-2-yl) pyromellitam diacetate [II] .This ester  was used to produce  novel  compounds through  two paths :- Path one:- Reaction of ester [II] with hydrazine in ethanol as a solvent to form the corresebonding  N,N‾-bis (benzothiazole-2-yl) –pyromellitamic acid hydrazide [III] which react with acetyl acetone in ethanol or with phthalic anhydride in dioxa

N, N′- bis[4-hydroxy phenyl] pyromillitdiimide [II] was prepared from the corresponding diamic acid , which was transfered to its new ester by the reaction with chloroethyl acetate [III ], [III] was used to prepare the novel hydrazide derivative [IV] , which was allowed to react with several aldehydes to yield the hydrazones [V – IX]. All the new compounds were synthesized , and characterized by their melting points .HNMR for some of them1FTIR,C,H,N analysis and ,

N, N′- bis[4-hydroxy phenyl] pyromillitdiimide [II] was prepared from the corresponding diamic acid , which was transfered to its new ester by the reaction with chloroethyl acetate [III ], [III] was used to prepare the novel hydrazide derivative [IV] , which was allowed to react with several aldehydes to yield the hydrazones [V – IX]. All the new compounds were synthesized , and characterized by their melting points .HNMR for some of them1FTIR,C,H,N analysis and ,

Cloud computing is the new technological trend for future generations. It represents a new way to use IT resources more efficiently. Cloud computing is one of the most technological models for developing and exploiting infrastructure resources in the world. Under the cloud, the user no longer needs to look for major financing to purchase infrastructure equipment as companies, especially small and medium-sized ones, can get the equipment as a service, rather than buying it as a product. The idea of ​​cloud computing dates back to the sixties of the last century, but this idea did not come into actual application until the beginning of the third millennium, at the hands of technology companies such as Apple, Hp, IBM, which had

This study assesses the short-term and long-term interactions between firm performance, financial education and political instability in the case of Malaysia Small to Medium Enterprises (SMEs). The simultaneous insertion of financial education and political instability within the study is done intentionally to inspect the effect of these two elements in one equation for the Malaysian economy. Using the bound testing methodology for cointegration and error correction models, advanced within an autoregressive distributed lag (ARDL) framework, we examine whether a long-run equilibrium connection survives between firm performance and the above mentioned independent variables. Using this method, we uncover evidence of a positive long-term link b

The 4-(?-bromo acetyl)-4?-toluene sulfonanilide (2) was used as key intermediate to synthesize new heterocyclic compounds. This bromo compound was synthesized via sulfonation of amino group of p-amino acetophenone using Hinsburg method with 4-toluene sulfonyl chloride to form 4-acetyl-4?-toluene sulfonanilide (1) which is used as a starting material in this work. This compound was brominated to yield compound (2) which is used as a precursor to synthesize new five and seven membered heterocyclic compounds such as substituted 1,3-oxazoles (3,4), 1,3-thiazole derivatives (5-7), thiourea compounds (8a,b), 1,3-Thiazoline-2-thione compounds (9a-f) and 1,2,5-triazepine compounds (11a-d). The synthesized compounds were identified depending u

Straight tendons in pretensioned members can cause high-tensile stresses in the concrete extreme fibers at end sections because of the absence of the bending stresses due to self-weight and superimposed loads and the dominance of the moment due to prestressing force alone. Accordingly, the concrete tensile stresses at the ends of a member prestressed with straight tendons may limit the service load capacity of the member. It is therefore important to establish limiting zone in the concrete section within which the prestressing force can be applied without causing tension in the extreme concrete fibers. Two practical methods are available to reduce the stresses at the end sections due to the prestressing force. The first method based