الفهرس 
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Abstract
In this work, the physicochemical characteristics were carried out for local base stock oil sample was delivered from Co-operative Petroleum Company. The delivered oil sample divided into sub-samples that well dissolve different concentrations (100, 200 and 300 ppm) of six heterocyclic compounds containing Sulfur and Nitrogen atoms synthesized by reaction of arylcarbamodithioate compounds with aroylacrylic acid compounds (301, 302, 303, 304, 305 and 306) then used these compounds as antioxidants for oil samples.
(301), R1 = CH3, R2 = CH3,
5-(2-oxo-2-{p-tolyl} ethyl)-2-thioxo-3-(p-tolyl) thiazolidin-4-one.
(302), R1 = CH3, R2 = OC6H13,
5-(2-[4-{hexyloxy} phenyl]-2-oxoethyl)-2-thioxo-3-(p-tolyl) thiazolidin-4-one.
(303), R1 = CH3, R2 = OC12H25,
5-(2-[4-{dodecyloxy} phenyl]-2-oxoethyl)-2-thioxo-3-(p-tolyl) thiazolidin-4-one.
(304), R1 = OCH3, R2 = CH3,
3-(4-methoxyphenyl)-5-(2-oxo-2-(p-tolyl) ethyl)-2-thioxothiazolidin-4-one.
(305), R1 = OCH3, R2 = OC6H13,
5-(2-(4-(hexyloxy) phenyl)-2-oxoethyl)-3-(4-methoxyphenyl)-2-thioxothiazolidin-4-one.
(306), R1 = OCH3, R2 = OC12H25,
5-(2-(4-(dodecyloxy) phenyl)-2-oxoethyl)-3-(4-methoxyphenyl)-2-thioxothiazolidin-4-one.
These six synthesized compounds were identified and were confirmed by different analysis methods such as elemental analysis, FT-IR and 1H-NMR.
The blended sub-samples were subjected to oxidation test by contacted with oxygen in the presence of water and an iron-copper catalyst at 95°C. The test carried out at fixed temperature and at oxidation periods of 24, 48, 72 and 96 hours according to the standard test method ASTM D 943. After each period reached, small samples were withdrawn for performing the viscosity and acid number tests and the data were recorded.
The obtained results were tabulated, were analyzed and were evaluated by comparison the results of oil samples contained different concentrations of antioxidant compounds with each others and with results of blank oil sample (contain zero ppm antioxidant) to reach to the optimized concentration of effective antioxidants.
The evaluation process was depended on time that oil withstand oxidation reactions, effect of length of hydrocarbon chain of prepared compounds, effect of type of substituted groups on benzene ring and viscosity and acid number values.
It was shown the prepared compounds proved successful behavior as antioxidants for controlling the oxidation process and the more effective antioxidants are those contain long hydrocarbon substitute chain of benzene ring as well as contain alkoxy groups attached to benzene rings. Also the study show the more effective concentration for these compounds was 300 ppm.