3-ethyl-2-sulfanylidene-1,3-thiazolidin-4-one

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2-[2-(2-Ethyl-3-methoxyisoindol-1-yl)vinyl]-3-ethylbenzothiazolium perchlorate (0.5 g) and 3-ethylrhodanine (0.3 g) were dissolved in a 1:1 acetronitrile/methanol solution. Triethylamine was added and the reaction mixture heated to reflux for 10 minutes. The dyes which separated out was dissolved in chloroform and passed through a column of silica gel. After recrystallization from a mixture of chloroform and methanol the dye melted at 252°-253° C. pyridine/methanol λ max 661 nm. the reaction mixture heated to reflux for 10 minutes The dyes which separated out was dissolved in chloroform After recrystallization from a mixture of chloroform and methanol the dye melted at 252°-253° C. pyridine/methanol λ max 661 nm

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2-[2-(2-Ethyl-3-methoxyisoindol-1-yl)vinyl]-3-ethylbenzothiazolium perchlorate (0.5 g) and 3-ethylrhodanine (0.3 g) were dissolved in a 1:1 acetronitrile/methanol solution. Triethylamine was added and the reaction mixture heated to reflux for 10 minutes. The dyes which separated out was dissolved in chloroform and passed through a column of silica gel. After recrystallization from a mixture of chloroform and methanol the dye melted at 252°-253° C. pyridine/methanol λ max 661 nm. the reaction mixture heated to reflux for 10 minutes The dyes which separated out was dissolved in chloroform After recrystallization from a mixture of chloroform and methanol the dye melted at 252°-253° C. pyridine/methanol λ max 661 nm

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: This dye was prepared by the interaction of 3-ethyl-rhodanine and 3-chloro-1-dimethylaminomethylene-2-ethyl-1H-isoindolium perchlorate in the presence of triethylamine. The dye after purification by recrystallization from methanol melted at 119° C. MeOH λ max 505 nm. The dye after purification by recrystallization from methanol melted at 119° C

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: This dye was prepared by the interaction of 3-ethyl-rhodanine and 3-chloro-1-dimethylaminomethylene-2-ethyl-1H-isoindolium perchlorate in the presence of triethylamine. The dye after purification by recrystallization from methanol melted at 119° C. MeOH λ max 505 nm. The dye after purification by recrystallization from methanol melted at 119° C

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 5 g. (0.033 m.) of 3-ethylrhodanine, 12 ml. of triethylorthoacetate and 35 ml. of acetic anhydride is heated under reflux for 18 hours and the solution is then concentrated in vacuo. The cooled residue is filtered and the solid is dissolved in ether. The ether solution is washed with water, dried and evaporated in vacuo to give 5-(1'-ethoxyethylidene)-3-ethylrhodanine. The latter (3.6 g.) is stirred with 15 ml. of dioxane, 15 ml. of water and 15 ml. of 10% sodium hydroxide solution for 4 hours. The resulting solution is concentrated in vacuo at 40°C. and the aqueous solution is washed with ether, decolorized, then made acidic with dilute hydrochloric acid. The precipitate is dissolved in 10% sodium hydroxide solution, washed with ether and the aqueous solution is made acidic with dilute hydrochloric acid to give the product, 3-ethyl-5-(1'-hydroxyethylidene)-rhodanine, m.p. 93°C. A mixture of 5 g under reflux for 18 hours the solution is then concentrated in vacuo The cooled residue is filtered the solid is dissolved in ether The ether solution is washed with water dried evaporated in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 1.9 g of 3-methoxyethoxyethoxyethylnaphtho[2,1-d]thiazoline-2-thion and 1.8 g of methyl p-toluenesulfonate were fed into a 50 ml short-neck flask provided with a reflux condenser. The resultant mixture was heated at 120° C. for 4 hours. After cooling the reaction mixture to room temperature followed by addition of 0.8 g of 3-ethylthiazolidine-4-on-2-thion and 24 ml of acetonitrile, the resultant mixture was cooled to 5° C., and 1.0 g of triethylamine was added thereto. After stirring at 10° C. for 24 hours, yellow precipitates thus obtained were suction-filtered, washed with 10 ml of acetonitrile three times, and dried to obtain the intended compound. provided with a reflux condenser yellow precipitates thus obtained were suction-filtered washed with 10 ml of acetonitrile three times dried to obtain the intended compound

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: N-(3-Chloro-5,5-dimethylcyclohex-2-en-1-ylidene)-pyrrolidinium perchlorate (3.1 g., 0.01 mol.), 3-ethylrhodanine (1.6 g., 0.011 mol.) and triethylamine (3.1 ml.) are dissolved in ethanol (20 ml.) and heated at reflux for 10 minutes. After chilling, the solid is collected on a filter, rinsed with ethanol and dried. After one recrystallization from pyridine/methanol, the yield of purified dye is 2.2 g. (65%), m.p. 234°-235°C. with decomposition. This dye is an excellent spectral sensitizer for photographic silver halide emulsions in the minus blue region of the spectrum as set forth in Table 2 hereinafter. heated at reflux for 10 minutes After chilling the solid is collected on a filter rinsed with ethanol dried After one recrystallization from pyridine/methanol

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Ethylisothiocyanate (10 g, 0.115 moles), 7.9 g(0.086 moles) mercaptoacetic acid and 5 mL pyridine in C6H6 was refluxed, cooled and filtered yielding 3-ethylrhodanine, which was used in the next step without any further purification. Reaction of 3-ethylrodanine with piperonal in the presence of sodium acetate was performed in CH3OH under refluxing for 1 h. The yellow precipitate obtained after cooling and filtration, was washed several times with CH3OH on the filter and crystallizated from CH3OH to give 3-ethyl-5-piperilidenerodanine. 1H-NMR(DMSO-d6, 300 MHz):7.72 (s, 1H), 7.1–7.3 (m, 3H), 6.14 (s, 2H), 3.95–4.15 (q, 2H), 1.15–1.20 (t, 3H). 13C-NMR (75.48 MHz): 12.76, 40.28, 103.07, 110.21, 110.47, 120.68, 127.89, 128.07, 134.01, 149.23, 150.74, 167.57, 193.68. (2) 3-Ethyl-5-piperilidene-rodanine (1 g, 3.4 mmoles) was added to a stirred solution of 0.16 g (6.8 mmoles) in 8 mL abs. ethanol and the mixture was refluxed for 30 min. To the solution cooled to room temperature 5 mL H2O were added and the mixture was hydrolized with 10% HCl and extracted with ether. The ether phase was separated, dried (MgSO4) and evaporated to an oil. Since the investigation by TLC of the crude reaction mixture indicated the presence of piperonal, the reaction mixture was dissolved in CH2Cl2 and the obtained solution was washed with 1M NaOH. The aqueous phase was extracted twice with CH2Cl2 and then neutralized with dilute HCl. Free thiol was extracted with ethyl ether. After concentration, the product was purified by column cromatography eluating with hexane/ethyl ether:8/2. Yield 0.4 g (62.4%). 1H-NMR(CDCl3, 300 MHz):7.69 (s, 1H), 7.7.25–7.29 (d, 1H, J 1.46), 7.1–7.18 (m, 1H), 6.85–6.9 (d, 1H, J 8.13), 6.01 (s, 2H), 4.75 (s, 1H), 4.28–4.38 (q, 2H, J 7.12), 1.35–1.42 (t, 3H, J 7.13). 13C-NMR (75.48 MHz): 14.20, 62.5, 101.41, 108.37, 109.43, 121.06, 125.45, 129.20, 134.68, 147.80, 148.05, 165.43. cooled filtered

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2-[2-(2-Ethyl-3-methoxyisoindol-1-yl)vinyl]-3-ethylbenzothiazolium perchlorate (0.5 g) and 3-ethylrhodanine (0.3 g) were dissolved in a 1:1 acetronitrile/methanol solution. Triethylamine was added and the reaction mixture heated to reflux for 10 minutes. The dyes which separated out was dissolved in chloroform and passed through a column of silica gel. After recrystallization from a mixture of chloroform and methanol the dye melted at 252°-253° C. pyridine/methanol λ max 661 nm. the reaction mixture heated to reflux for 10 minutes The dyes which separated out was dissolved in chloroform After recrystallization from a mixture of chloroform and methanol the dye melted at 252°-253° C. pyridine/methanol λ max 661 nm

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: This dye was prepared by the interaction of 3-ethyl-rhodanine and 3-chloro-1-dimethylaminomethylene-2-ethyl-1H-isoindolium perchlorate in the presence of triethylamine. The dye after purification by recrystallization from methanol melted at 119° C. MeOH λ max 505 nm. The dye after purification by recrystallization from methanol melted at 119° C