Fresh 5-alkyl 1,3,4-oxadiazole 2-thione derived functions were synthesized by the converted of carboxylic acid to ester by esterfication or secondary aminoalkane to ester by treated with ethylchloroacetate to give compound ( 1 ) this compound treated with hydrazine hydrate to give acerb hydrazide ( 2 ) and with K hydrated oxide and C disulfide to give 1,3,4-oxadiazole derivative compounds ( 3 ) this compounds treated with different primary aminoalkane and with terephthaldehyde to give mannich bases ( 4 ) .
Heterocyclic compounds are really of import compounds which have been found to keep important biological activity are represent are of import mediety in creative activity of fresh medical stuffs, hardship of biological activities and pharmaceutical utilizations have been attributed to them such as anti-inflammatory, fungicidal, antibacterial, antitumor and analgetic ( 1-4 ) .
The oxadiazole chemical science has been developed extensively and still developing. Soon, there are a figure of drugs used clinically, which comprise oxadiazole, tetrazole mediety in association with assorted heterocyclic rings ( 5 ) .
A series of permutation tetrazole have have been synthesized by different methods such as from pyridine ( 2-azido azines ) which equilibrium with amalgamate tetrazoles ( 6 ) . Besides, the mannich bases have a broad biological activates. A new 5-alkyl and 3- ( 2,4-dimethylphenyl ) substituted 1,3,4-oxadiazole-2-thionederivatives were synthesized by the ring closing reaction of assorted acyl hydrazide with carbondisulfide.Dawoodhas synthesized some of mannich bases get downing from hydrazide derived functions and found that these derived functions have biological activity.
Consequently, we wish to describe herein the synthesis of compounds which possesses a chemically of import to accomplish better disinfectant, antibacterial — -etc.
1-Synthesis of 2-Acid hydrazide ( 2 ) ( 9 )
Acid hydrazide was synthesized by add-on of the hydrazine monohydrate ( 80 % ) ( 0.01mol. ) to ester compounds ( 19 ) ( 0.01mol. ) with stirring, so the ethyl alcohol absolute ( 10 milliliter ) was added and refluxed until the precipitate formed ( 1.5hrs ) . After chilling, the precipitate was filtered and recrystallized from ethyl alcohol.
2-Synthesis of 5- ( alkyl ) -1,3,4-oxadiazole-2 ( 3H ) -thione ( 3 ) ( 10 )
A mixture of acerb hydrazide ( 0.01mol ) in absolute ethyl alcohol ( 25ml ) with ( 0.02mol ) of K hydrated oxide was stirred in ice bath, C disulphide ( 0.02mol ) was added bead wise with smartly stirring, the reaction mixture was refluxed for 3hrs. After vaporization under decreased force per unit area, the residue was poured into acidified H2O.The precipitate was filtered, dried and re crystallized from ethyl alcohol.
3-Synthesis 3,3′- ( 1,4-phenylenebis ( ( N-sub-phenyl ) methylene ) ) Bi ( 5-alkyl-2-yl ) -1,3,4-oxadiazole-2 ( 3H ) -thione ( 4a-e ) ( 11 )
To ethanolic solution of oxadiazole compound ( 3 ) ( 0.02mol ) , terephthaldehyde ( 0.01mol ) was added and stirred for ( 90min ) . , in ice bath. Then the cold solution of different primary aminoalkane ( 0.02mol ) were added bead wise while stirring. The resulting mixture was refluxed for 6-7hrs in H2O bath the residue obtained after the vaporization of the dissolver under decreased force per unit area was recrystallized from ethyl alcohol. m.p= ( 107-110 ) 0C for compound ( 1 ) output ( 66 % ) , m.p= ( 110-112 ) 0C for compound ( 2 ) , output ( 70 % ) . m.p= ( 133-135 ) 0C for compound ( 3 ) output ( 77 % ) m.p= ( 191-193 ) 0C for compound ( 4 ) output ( 69 % ) m.p= ( 199-200 ) 0C for compound ( vitamin E ) output ( 62 % ) .
Consequences and treatment
Compound ( 3 ) was synthesized from the reaction of compound ( 2 ) with C disulfide and K hydrated oxide in absolute ethyl alcohol. This compound was characterized by its thaw point and F.T.IR spectrum. The F.T.IR spectrum of compound ( 3 ) indicated the disappearing of carbonyl group set at ( 1685 ) cm-1 and visual aspect of sets at ( 1610 ) cm-1 due to ? ( C=N ) of oxadiazole ring and at ( 1290 ) cm-1 due to ? ( C-O-C ) ( cyclic ) group in oxadiazole, all these good groundss for the construction assigned to this compound. Besides a strong set at ( 1078 ) cm-1 which due to ? ( C=S ) thione group.
Compound ( 3 ) may be found as two tautomeric signifiers thione ( 3 ) and thiol ( 3a ) construction.
There is much grounds proved for penchant of compound ( 3 ) because it is more stable than ( 3a ) . Compound ( 3 ) may be found as dimmer ( 3b ) , this dimer has hydrogen adhering between the ( C=S ) of the first molecule and ( -NH ) of the 2nd molecule.
There are many theoretical computations which proved that the compound ( 3 ) is more stable than ( 3a ) by utilizing the chem. Office plan 2006, as the measurement of bond lengths and bonds angles between atoms.
The length of the bond between ( -N-C=S ) is ( 1.4 0A ) in compound ( 3 ) but in ( 3a ) ( -N=C-SH ) is ( 1.30A ) , ( -O-C=S ) is ( 1.50A ) in ( 21 ) but ( O-C-SH ) is ( 1.40A ) these values lead to diminish the emphasis in oxadiazole ring in compound ( 3 ) is less than emphasis in compound ( 3a ) .the distance between ( N-H ) is ( 1.00A ) but the distance between ( -S-H ) is ( 1.30A ) , these values indicated that the more preferable signifier is ( 3 ) .
word picture of ( 1,4-phenylenebis ( ( N-sub-phenyl ) methylene ) ) Bi ( 5- ( furan-2-yl ) -1,3,4-oxadiazole-2 ( 3H ) -thione ( 4a-e ) .
These compounds were prepared from the reaction of two moles of primary aminoalkane, oxadiazole derived functions ( 3 ) , and one mole of terephthaldehyde in ethanol absolute as a dissolver.
Compounds ( 4a-e ) are a Mannich bases because the reactants are aldehyde derived functions, secondary aminoalkane and primary aminoalkane, The constructions of the prepared compounds ( 4a-e ) are characterized by C.H.N. analysis and FT.IR, 1HNMR, spectrometry, the thaw point is recorded and the pureness of these compounds are checked by T.L.C. technique and gas chromatography.
The FT.IR spectra of compounds ( 4a-e ) , showed the undermentioned sets: at ( 3371-3304 ) cm-1 due to ? ( NH ) , at ( 2887-3837 ) cm-1 for ? ( CH ) aliphatic, and at ( 1091-1111 ) cm-1 for ? ( C=S ) thione group. All the spectral informations for these compounds are listed in tabular array ( 1 ) .
Table ( 1 ) : FT-IR spectral informations of compounds ( 4a-e ) .
? ( C-H )
? ( N-H )
? ( C=S )
Other bands cm-1
? ( C=O ) 1694
? ( -NO2 ) 1545,1330
? ( C=N ) 1631
? ( C-Cl ) 639
? ( C=N ) 1633
1HNMR spectrum of compound ( a ) shows singlet signal at i?¤ ( 2.0 ) ppm for ( -CH3 ) ( a ) ( NH ) proton is appeared as a vest at ( 4.338 ) ppm ( B ) . Another singlet signal appeared at i?¤ ( 4.919 ) ppm of a proton of ( -CH ) ( proton degree Celsius ) . A three signals appeared ati?¤ ( 5.4 ) ppm for ( a proton vitamin D ) in furan ring, a doublet signal appeared at ( 6.8 ) ppm for ( proton vitamin E ) in the same ring. Multiplate signal appeared at i?¤ ( 7.4-7.8 ) ppm of aromatic ring protons but another doublet signal appeared at i?¤ ( 5.4 ) protons ( vitamin D, vitamin E ) ppm due to proton in furan ring.
1H-NMR spectrum of compound ( vitamin E ) , shows the undermentioned characteristic chemical displacements ( DMSO-d6, ppm ) . The aromatic protons appeared at: ? ( 7.5-8.8 ) ppm, ( -CH ) proton at i?¤ ( 6.33 ) ppm fused with oxadiazole ring, besides the set at i?¤ ( 5.64 ) ppm was appeared due to ( -NH ) , a two protons of ( -CH2 ) group gave a signal at i?¤ ( 4.43 ) ppm ( 12 ) .
1H-NMR spectrum of compound ( vitamin E )