2.1. Chemistry

All reagents and solvents used in this research were purchased from Sigma-Aldrich (Munich, Germany) and Merck Co. (Darmstadt, Germany) and used without further purification. Thin-layer chromatography (TLC) on plates covered with silica gel (aluminum oxide 60 F-254, Merck Co., Kenilworth, NJ, USA) was used to check the purity of the obtained compounds and to monitor the progress of the reaction. Chloroform–ethanol mixture in the 10:1 (v/v) ratio was used as the mobile phase. The spots were detected by irradiation with UV light at a wavelength of λ = 254 nm. ¹H NMR and ¹³C NMR spectra were recorded on the Bruker Avance 300 and 600 apparatus (Bruker BioSpin GmbH, Rheinstetten, Germany). The melting points of the obtained compounds were measured with a Fisher–Johns apparatus (Fisher Scientific, Schwerte, Germany) and presented without any correction. The elemental analysis was determined by the Perkin Elmer 2400 series II CHNS/O analyzer (Waltham, MA, USA), and the results were within ±0.4% of the theoretical value.

The 2,4,6-trimethylbenzenesulfonyl hydrazones were synthesized with the use of the method described earlier by our group for the synthesis of hydrazide–hydrazones [32,33,34].

We dissolved 0.01 mole of 2,4,6-trimethylbenzenesulfonohydrazide (1) in ethanol (5 mL, 96%). Then, 0.011 mole of appropriate substituted benzaldehyde was added, and the mixture was heated under reflux for 3 h. The substituted benzaldehydes used in this research are presented in Scheme 1. After that, the solution was cooled to room temperature and placed in the refrigerator for 24 h. Subsequently the precipitate formed was filtered off and re-crystallized from ethanol (96%).

N-[(3-Ethoxy-2-hydroxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (2)

Yellow powder; CAS Number: 1799087-18-5; M.p.: 132 °C; Yield: 52%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 1.29–1.31 (t, 3H, CH₃, J = 9 Hz, J = 6 Hz), 2.24 (s, 3H, CH₃), 2.62 (s, 6H, 2 × CH₃), 3.98–4.05 (q, 2H, CH₂, J = 6 Hz), 6.71–6.76 (t, 1H, ArH, J = 9 Hz, J = 6 Hz), 6.86–6.92 (m, 1H, ArH), 6.94–7.00 (m, 1H, ArH), 7.05 (s, 2H, ArH), 8.20 (s, 1H, =CH), 8.98 (s, 1H, OH), 11.54 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 15.18 (CH₃), 21.63 (2 × CH₃), 23.14 (CH₃), 64.52 (CH₂), 118.85, 120.19, 132.16, 133.49, 139.64, 142.86, 146.53, 147.45 (10 × C_ar), 147.54 (=CH), 149.22, 163.38 (2 × C_ar).

N-[(3,4-Dimethoxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (3)

Yellowish powder; CAS Number: 1799143-26-2; M.p.: 140 °C; Yield: 61%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.23 (s, 3H, CH₃), 2.65 (s, 6H, 2 × CH₃), 3.72 (s, 3H, OCH₃), 3.75 (s, 3H, OCH₃), 6.93–6.95 (d, 1H, ArH, J = 6 Hz), 7.04 (s, 2H, ArH), 7.05–7.08 (m, 1H, ArH), 7.81 (s, 1H, ArH), 8.64 (s, 1H, =CH), 11.38 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 20.87 (2 × CH₃), 23.23 (CH₃), 56.79 (OCH₃), 57.89 (OCH₃), 111.91, 114.10, 122.11, 127.07, 129.35, 132.05, 133.84, 139.73 (10 × C_ar), 142.68 (=CH), 149.32, 150.88 (2 × C_ar).

N-[(3-Ethoxy-4-hydroxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (4)

Brown powder; CAS Number: 1799022-47-1; M.p.: 142 °C; Yield: 52%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 1.30–1.32 (t, 3H, CH₃), 2.23 (s, 3H, CH₃), 2.64 (s, 6H, 2 × CH₃), 3.94–4.01 (q, 2H, CH₂, J = 9 Hz, J = 6 Hz), 6.74–6.77 (d, 1H, ArH, J = 9 Hz), 6.86–6.90 (m, 1H, ArH), 7.03 (s, 2H, ArH), 7.22–7.25 (d, 1H, ArH, J = 9 Hz), 7.76 (s, 1H, OH), 8.55 (s, 1H, =CH), 11.26 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 15.10 (CH₃), 20.87 (2 × CH₃), 23.24 (CH₃), 64.52 (CH₂), 115.92, 125.74, 125.88, 132.03, 133.88, 139.71, 142.62, 146.26 (10 × C_ar), 147.57 (=CH), 149.35, 150.57 (2 × C_ar).

N-[(2,4-Dimethoxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (5)

Orange powder; CAS Number: 1799183-35-9; M.p.: 140 °C; Yield: 45%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.23 (s, 3H, CH₃), 2.61 (s, 6H, 2 × CH₃), 3.76 (s, 3H, OCH₃), 3.78 (s, 3H, OCH₃), 6.53–6.55 (m, 2H, ArH), 7.02 (s, 2H, ArH), 7.42–7.45 (d, 1H, ArH, J = 9 Hz), 8.13 (s, 1H, =CH), 11.23 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 20.86 (2 × CH₃), 23.21 (CH₃), 56.04 (OCH₃), 56.79 (OCH₃), 98.66, 106.87, 115.09, 126.39, 132.04, 133.90, 139.63, 141.62 (10 × C_ar), 142.58 (=CH), 159.17, 162.70 (2 × C_ar).

N-[(2,3-Dimethoxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (6)

White powder; CAS Number: 1799021-56-9; M.p.: 118 °C; Yield: 43%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.23 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 3.70 (s, 3H, OCH₃), 3.79 (s, 3H, OCH₃), 7.03 (s, 2H, ArH), 7.04–7.12 (m, 3H, ArH), 8.17 (s, 1H, =CH), 11.54 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 20.89 (2 × CH₃), 23.20 (CH₃), 56.81 (OCH₃), 56.99 (OCH₃), 112.11, 115.09, 123.23, 127.77, 129.15, 132.75, 133.64, 138.13 (10 × C_ar), 142.78 (=CH), 150.31, 151.98 (2 × C_ar).

N-[(2-Iodophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (7)

Bright yellow powder; M.p.: 170 °C; Yield: 76%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.24 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 7.05 (s, 2H, ArH), 7.08–7.14 (m, 1H, ArH), 7.36–7.41 (t, 1H, ArH, J = 6 Hz, J = 9 Hz), 7.53–7.56 (d, 1H, ArH, J = 9 Hz), 7.85–7.88 (d, 1H, ArH, J = 9 Hz), 8.13 (s, 1H, =CH), 11.87 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.18 (2 × CH₃), 100.15, 126.57, 129.07, 132.08, 132.17, 133.70, 135.67, 139.60, 140.15 (11 × C_ar), 142.91 (=CH), 148.51 (C_ar).

N-[(3-Iodophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (8)

Orange powder; M.p.: 128 °C; Yield: 78%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.24 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 7.05 (s, 2H, ArH), 7.15–7.20 (t, 1H, ArH, J = 9 Hz, J = 6 Hz), 7.49–7.51 (d, 1H, ArH, J = 6 Hz), 7.69–7.72 (m, 1H, ArH), 7.86–7.90 (m, 1H, ArH), 7.83 (s, 1H, =CH), 11.76 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.16 (2 × CH₃), 95.68, 126.21, 131.39, 132.14, 133.73, 135.26, 136.58, 138.66, 139.63 (11 × C_ar), 142.88 (=CH), 143.88 (C_ar).

N-[(4-Iodophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (9)

Light yellow powder; M.p.: 166 °C; Yield: 46%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.23 (s, 3H, CH₃), 2.62 (s, 6H, 2 × CH₃), 7.04 (s, 2H, ArH), 7.26–7.29 (d, 2H, ArH, J = 9 Hz), 7.88–7.91 (d, 2H, ArH, J = 9 Hz), 8.67 (s, 1H, =CH), 11.68 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 21.03 (CH₃), 23.19 (2 × CH₃), 99.45, 128.75, 130.55, 132.12, 133.66, 138.12, 138.33, 139.64 (12 × C_ar), 142.82 (=CH).

N-[(2-Fluorophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (10)

Bright yellow powder; CAS Number: 1799182-76-5; M.p.: 161 °C; Yield: 54%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.24 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 7.05 (s, 2H, ArH), 7.19–7.27 (m, 1H, ArH), 7.35–7.45 (m, 1H, ArH), 7.55–7.61 (m, 1H, ArH), 7.85–7.88 (d, 1H, ArH, J = 9 Hz), 8.09 (s, 1H, =CH), 11.77 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.15 (2 × CH₃), 116.61, 121.77, 125.41, 126.22, 132.14, 133.68, 138.53, 139.72 (10 × C_ar), 142.89 (=CH), 155.57, 159.99 (2 × C_ar).

N-[(3-Fluorophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (11)

Bright yellow powder; CAS Number: 1799086-95-5; M.p.: 126 °C; Yield: 7%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.26 (s, 3H, CH₃), 2.62 (s, 6H, 2 × CH₃), 7.07 (s, 2H, ArH), 7.20–7.28 (m, 1H, ArH), 7.38–7.44 (m, 1H, ArH), 7.59–7.65 (m, 1H, ArH), 7.88–7.90 (d, 1H, ArH, J = 9 Hz), 8.19 (s, 1H, =CH), 11.97 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.90 (CH₃), 23.20 (2 × CH₃), 117.62, 121.87, 126.11, 126.72, 132.34, 133.98, 138.23, 139.92 (10 × C_ar), 142.95 (=CH), 155.67, 159.19 (2 × C_ar).

N-[(4-Fluorophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (12)

Orange powder; CAS Number: 1799193-67-1; M.p.: 168 °C; Yield: 40%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.23 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 7.04 (s, 2H, ArH), 7.19–7.25 (m, 2H, ArH), 7.52–7.57 (m, 2H, ArH), 7.90 (s, 1H, =CH), 11.60 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.88 (CH₃), 23.19 (2 × CH₃), 116.29, 129.07, 132.10, 133.80, 139.67, 144.76 (10 × C_ar), 142.76 (=CH), 160.89, 162.57 (2 × C_ar).

N-[(2-Bromophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (13)

Yellow powder; M.p.: 156 °C; Yield: 14%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.24 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 7.05 (s, 2H, ArH), 7.27–7.32 (m, 1H, ArH), 7.39–7.41 (t, 1H, ArH, J = 3 Hz), 7.48–7.53 (m, 1H, ArH), 7.60–7.65 (m, 1H, ArH), 8.24 (s, 1H, =CH), 11.88 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.90 (CH₃), 23.16 (2 × CH₃), 123.58, 126.85, 128.61, 129.06, 132.97, 133.68, 133.91, 139.62 (10 × C_ar), 142.93 (=CH), 143.87, 161.24 (2 × C_ar).

N-[(3-Bromophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (14)

Bright yellow powder; CAS Number: 1799080-75-3; M.p.: 150 °C; Yield: 73%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.23 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 7.05 (s, 2H, ArH), 7.31–7.36 (t, 1H, ArH, J = 6 Hz, J = 9 Hz), 7.48–7.57 (m, 2H, ArH), 7.67–7.68 (m, 1H, ArH), 7.87 (s, 1H, =CH), 11.79 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.15 (2 × CH₃), 122.55, 125.86, 129.35, 131.46, 132.14, 132.84, 133.75, 136.76, 139.69 (11 × C_ar), 142.88 (=CH), 143.90 (C_ar).

N-[(4-Bromophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (15)

Bright yellow powder; CAS Number: 1799088-79-1; M.p.: 155 °C; Yield: 67%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.24 (s, 3H, CH₃), 2.62 (s, 6H, 2 × CH₃), 7.04 (s, 2H, ArH), 7.42–7.45 (d, 2H, ArH, J = 9 Hz), 7.57–7.60 (d, 2H, ArH, J = 9 Hz), 7.88 (s, 1H, =CH), 11.70 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.19 (2 × CH₃), 123.55, 128.80, 132.12, 132.31, 133.57, 133.76, 139.66 (11 × C_ar), 142.82 (=CH), 144.53 (C_ar).

N-[(2-Chlorophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (16)

Yellow powder; CAS Number: 1799120-48-1; M.p.: 125 °C; Yield: 35%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.24 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 7.05 (s, 2H, ArH), 7.32–7.41 (m, 1H, ArH), 7.45–7.51 (m, 1H, ArH), 7.57–7.65 (m, 2H, ArH), 8.98 (s, 1H, =CH), 11.87 (s, 1H, NH); ¹³C NMR (75 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.17 (2 × CH₃), 126.49, 128.68, 130.69, 131.41, 132.17, 133.18, 135.15, 139.64, 141.49 (11 × C_ar), 142.95 (=CH), 158.77 (C_ar).

N-[(4-Chlorophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (17)

Yellow powder; CAS Number: 1798924-70-5; M.p.: 122 °C; Yield: 29%; ¹H NMR (300 MHz, DMSO-d₆) δ (ppm): 2.24 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 7.04 (s, 2H, ArH), 7.43–7.46 (d, 1H, ArH, J = 9 Hz), 7.49–7.52 (d, 1H, ArH, J = 9 Hz), 7.57–7.60 (d, 1H, ArH, J = 9 Hz), 7.89–7.92 (d, 1H, ArH, J = 9 Hz), 8.72 (s, 1H, =CH), 11.70 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.19 (2 × CH₃), 128.57, 129.29, 130.51, 132.12, 133.09, 133.23, 133.77, 134.81, 136.56, 139.66 (10 × C_ar), 142.82 (=CH), 144.44, 161.08 (2 × C_ar).

N-[(3-Chlorophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (18)

Bright yellow powder; CAS Number: 1799187-65-7; M.p.: 140–143 °C; Yield: 41%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.25 (s, 3H, CH₃), 2.64 (s, 6H, 2 × CH₃), 7.06 (s, 2H, ArH), 7.40–7.48 (m, 1H, ArH), 7.53–7.54 (m, 1H, ArH), 7.56–7.57 (d, 1H, ArH, J = 6 Hz), 7.60–7.62 (m, 1H, ArH, J = 12 Hz), 8.73 (s, 1H, =CH), 11.81 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.88 (CH₃), 23.15 (2 × CH₃), 125.46, 126.42, 127.39, 129.95, 132.12, 134.17, 136.25, 139.64 (10 × C_ar), 142.86 (=CH), 143.98, 161.05 (2 × C_ar).

N-[(2-Chloro-3-methoxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (19)

Bright yellow powder; M.p.: 158–160 °C; Yield: 47%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.25 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 3.85 (s, 3H, OCH₃), 7.06 (s, 2H, ArH), 7.14–7.16 (m, 1H, ArH), 7.30–7.35 (m, 1H, ArH), 7.74–7.75 (d, 1H, ArH, J = 6 Hz), 8.31 (s, 1H, =CH), 11.87 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.15 (2 × CH₃), 56.93 (OCH₃), 115.77, 117.87, 119.94, 123.52, 128.50, 132.15, 139.63, 141.76 (10 × C_ar), 142.92 (=CH), 155.37, 158.99 (2 × C_ar).

N-[(3-Chloro-4-methoxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (20)

Yellow powder; M.p.: 159–162 °C; Yield: 3%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.26 (s, 3H, CH₃), 2.62 (s, 6H, 2 × CH₃), 3.89 (s, 3H, OCH₃), 7.05 (s, 2H, ArH), 7.29–7.30 (d, 1H, ArH, J = 6 Hz), 7.82–7.84 (d, 1H, ArH, J = 12 Hz), 7.94–7.95 (d, 1H, ArH, J = 6 Hz), 8.65 (s, 1H, =CH), 11.88 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.95 (CH₃), 24.28 (2 × CH₃), 56.93 (OCH₃), 111.50, 113.55, 122.14, 127.82, 129.42, 129.65, 132.99, 133.12 (10 × C_ar), 142.15 (=CH), 157.24, 160.43 (2 × C_ar).

N-[(3-Bromo-4-methoxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (21)

Pink powder; CAS Number: 1799222-06-2; M.p.: 158–160 °C; Yield: 76%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.25 (s, 3H, CH₃), 2.64 (s, 6H, 2 × CH₃), 3.86 (s, 3H, OCH₃), 7.05 (s, 2H, ArH), 7.13–7.14 (d, 1H, ArH, J = 6 Hz), 7.49–7.50 (m, 1H, ArH), 7.71–7.72 (d, 1H, ArH, J = 6 Hz), 7.83 (s, 1H, =CH), 11.56 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.88 (CH₃), 23.18 (2 × CH₃), 56.90 (OCH₃), 111.50, 113.30, 127.98, 128.39, 131.00, 132.09, 133.82, 139.63 (10 × C_ar), 142.75 (=CH), 144.14, 156.96 (2 × C_ar).

N-[(5-Bromo-2-hydroxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (22)

Yellow powder; CAS Number: 1799182-63-0; M.p.: 160–163 °C; Yield: 49%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.26 (s, 3H, CH₃), 2.62 (s, 6H, 2 × CH₃), 6.81–6.82 (d, 1H, ArH, J = 6 Hz), 6.96–6.97 (d, 1H, ArH, J = 6 Hz), 7.07 (s, 2H, ArH), 7.51–7.55 (m, 1H, ArH), 8.11 (s, 1H, =CH), 10.39 (s, 1H, OH), 11.70 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.07 (2 × CH₃), 111.06, 118.96, 119.40, 128.53, 132.18, 139.59, 141.83 (9 × C_ar), 142.94 (=CH), 155.83, 158.13, 161.21 (3 × C_ar).

N-[(3,5-Dichloro-2-hydroxyphenyl)methylidene]-2,4,6-trimetylbenzenesulfonohydrazide (23)

Yellow powder; M.p.: 154–158 °C; Yield: 69%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.26 (s, 3H, CH₃), 2.62 (s, 6H, 2 × CH₃), 7.10 (s, 2H, ArH), 7.44–7.45 (d, 1H, ArH, J = 6 Hz), 7.75–7.76 (d, 1H, ArH, J = 6 Hz), 8.15 (s, 1H, =CH), 10.72 (s, 1H, OH), 12.11 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.91 (CH₃), 22.99 (2 × CH₃), 120.78, 124.0, 126.69, 130.35, 132.31, 139.60, 143.25 (9 × C_ar), 143.75 (=CH), 151.37, 153.80, 164.02 (3 × C_ar).

N-[(2-Hydroxy-3,5-diiodophenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (24)

Yellow powder; M.p.: 280 °C; Yield: 66%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.27 (s, 3H, CH₃), 2.61 (s, 6H, 2 × CH₃), 7.10 (s, 2H, ArH), 7.74–7.75 (d, 1H, ArH, J = 6 Hz), 7.99–8.00 (d, 1H, ArH, J = 6 Hz), 8.03 (s, 1H, =CH), 11.04 (s, 1H, OH), 12.20 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.91 (CH₃), 22.94 (2 × CH₃), 83.40, 88.67, 121.45, 132.37, 132.96, 138.26, 139.58 (9 × C_ar), 143.34 (=CH), 145.43, 146.98, 155.86 (3 × C_ar).

N-[(2-Bromo-3-hydroxy-4-methoxyphenyl)methylidene]-2,4,6-trimethylbenzenesulfonohydrazide (25)

Brown powder; CAS Number: 1799215-12-5; M.p.: 180 °C; Yield: 55%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.25 (s, 3H, CH₃), 2.63 (s, 6H, 2 × CH₃), 3.83 (s, 3H, OCH₃), 7.02–7.03 (d, 1H, ArH, J = 6 Hz), 7.05 (s, 2H, ArH), 7.11–7.13 (m, 1H, ArH), 8.20 (s, 1H, =CH), 8.91 (s, 1H, OH), 11.61 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.89 (CH₃), 23.20 (2 × CH₃), 56.80 (OCH₃), 111.57, 117.25, 119.60, 125.89, 132.10, 139.61, 142.76, 144.16 (10 × C_ar), 144.92 (=CH), 149.85, 161.11 (2 × C_ar).

2,4,6-Trimethyl-N-(phenylmethylidene)benzenesulfonohydrazide (26)

White powder; CAS Number: 16182-18-6; M.p.: 131–133 °C; Yield: 10%; ¹H NMR (600 MHz, DMSO-d₆) δ (ppm): 2.24 (s, 3H, CH₃), 2.65 (s, 6H, 2 × CH₃), 7.05 (s, 2H, ArH), 7.35–7.40 (m, 3H, ArH), 7.49–7.51 (m, 2H, ArH), 7.91 (s, 1H, =CH), 11.59 (s, 1H, NH); ¹³C NMR (150 MHz, DMSO-d₆) δ (ppm): 20.88 (CH₃), 23.21 (2 × CH₃), 126.95, 129.29, 130.35, 132.10, 133.82, 134.30, 139.68, 142.76 (12 × C_ar), 145.73 (=CH).

Examples of ¹H NMR and ¹³C NMR spectra of synthesized 2,4,6-trimethylbenzenesulfonyl hydrazones are presented in the Supplementary Materials (Figures S1–S8).