Monatsh Chem 139, 1279–1283 (2008) DOI 10.1007/s00706-008-0933-1 Printed in The Netherlands Synthesis of corrosion preventive long-chain N-alkyl-2-(phenylthio)- acetohydrazides and 2-oxo-2-phenylethyl-2-alkanoylhydrazinecarbodithioates Ayhan Yıldırım, Mehmet C ° etin Department of Chemistry, Faculty of Science and Arts, Uluda g University, Bursa, Turkey Received 21 February 2008; Accepted 16 March 2008; Published online 9 June 2008 # Springer-Verlag 2008 Abstract Long-chain N-alkyl-2-(phenylthio)acetohy- drazides were synthesized via the reactions of 2- (phenylthio)acetohydrazide with long-straight-chain aldehydes and then reduction with sodium borohy- dride. The reactions of long-straight-chain hydra- zides with carbon disulfide in alkaline media give the corresponding carbodithioate salts. Heating of potas- sium 2-alkanoylhydrazinecarbodithioates with phena- cyl bromide do not yield cyclization and failed to give the corresponding long-chain thiazolidine-2-thiones, but gave the corresponding 2-oxo-2-phenylethyl- 2-alkanoylhydrazinecarbodithioates via nucleophilic substitution reaction. In addition, the synthesized compounds were tested for their corrosion prevention capabilities in acidic or in mineral oil media. Keywords Fatty acids; Surface; Corrosion inhibitors; Acidic; Mineral oil media. Introduction Long-chain fatty acids and compounds derived from them, especially, N, S, or P derivatives find wide applications in every area of industrial activity while many of them are products or constituents of products. Fat-based emulsifiers, fabric soften- ers and conditioners, synthetic lubricants, oil field chemicals, derivatives using in metalworking fluids, flotation, textiles, cosmetics, and toiletries are ex- amples [1]. The largest use of N and=or S containing fatty acids derivatives in oil field chemicals is in corrosion inhibitors. The prior art has disclosed a wide variety of chemical compounds which effectively reduce the corrosion. Fatty diethanolamides [2], long-chain im- idazolines [3], isoxazolines and isoxazolidines [4], mercapto oxadiazoles and triazoles [5, 6], and thio- semicarbazides [7] are well known compounds in corrosion literature. In general, S-containing deriv- atives are among the most effective inhibitors. This is due to the fact that lone electron pairs at sulfur can easily be polarized. We report herein the synthesis of fatty N-alkyl- 2-(phenylthio)acetohydrazides 4a–4c and 2-oxo- 2-phenylethyl-2-alkanoylhydrazinecarbodithioates 7a–7d. It was found that under the reaction condi- tions tested carbodithioates 6a–6d give the 2-oxo- 2-phenylethyl-2 alkanoylhydrazine carbodithioates 7a–7d and do not yield cyclization to afford thi- azolidine-2-thiones 8a–8d. We also investigate the corrosion prevention properties of the synthesized compounds in 2 M HCl acidic media or paraffin based mineral oil media. Results and discussion There are many papers related to the reactions be- tween a variety of substrates and the products Correspondence: Ayhan Yıldırım, Department of Chemistry, Faculty of Science and Arts, Uluda g University, 16059 Bursa, Turkey. E-mail: yildirim@uludag.edu.tr