Preparation of 2-chlorobenzaldehyde
2-chlorobenzaldehyde is prepared by hydrolysis of 1-chloro-2-(dichloromethyl)benzene in acidic medium
To a three-necked 1 liter round-bottomed flask, equipped with mechanical stirrer, thermometer 500 g of a concentrated sulfuric acid and 250 g of freshly distilled 1-chloro-2-(dichloromethyl)benzene were placed. The reaction flask was connected via tube with an absorbing flask for hydrogen chloride. The reaction mixture was stirred with such rate of stirring so that the oil and sulfuric acid formed emulsion. During the reaction huge amount of hydrogen chloride was released and the temperature spontaneously dropped. When release of hydrogen chloride decreases, the flask was heated for 12 hours, at temperature 30-40° C. When hydrogen chloride stops to evaluate the reaction mixture is poured into 3 liters of cold water, allowed to settle, decanted upper aqueous layer, and the residue was carefully separated in a separatory funnel, rinsed with cold water added with sodium carbonate (sodium carbonate must not be used in large excess), and then water. The oil was distilled with super heated steam (120 to 140° C), yielding 150 g (53.3% of theory) of 2-chlorobenzaldehyde. 2-chlorobenzaldehyde is colorless liquid with melting point 11 ° C and a sharp odor.
Препаративная органическая химия, Вульфсон Н.С., 195-196, 1959 (Preparative organic chemistry, Wolfson N. S., 195-196, 1959)
By slightly modified procedure the 2-chlorobenzal chloride (or 2-chlorobenzal bromide) is stirred with eight times its weight of concentrated sulfuric acid in a three-necked flask with a ground sleeve, stirrer, reflux condenser, and a wide capillary serving as gas-inlet tube. Nitrogen is passed in through the capillary, and simultaneously the vacuum of a water pump is applied to the upper end of the reflux condenser. A vigorous evolution of hydrogen chloride (or hydrogen bromide) takes place at room temperature if not the reaction mixture is gently heated in the water bath (or oil bath). The reaction mixture changes the color to an intense red-brown color and the evolution of hydrogen chloride (or hydrogen bromide) ceases in about 1-2 hours. Then the mixture is poured on to ice and the 2-chlorobenzaldehyde formed is extracted several times with ether, the ethereal extracts are neutralized with sodium bicarbonate solution and then washed with water and dried over magnesium sulfate. After evaporation of the ether, the residue is distilled in vacuo b.p. 84°C/10mm. The yield of 2-chlorobenzaldehyde is 70%, m.p. 9-11 °C; b.p. 209-215 °C; b.p.84°C/10mm; n20/D 1.566.
Organicum. Practical Handbook of Organic Chemistry, by Heinz Becker, Werner Berger and Günter Domschke, Addison-Wesley Pub. Co, 203-204, (1973)
2-Chlorobenzaldehyde, 89-98-5, O-CHLOROBENZALDEHYDE, Benzaldehyde, 2-chloro-, Chlorobenzaldehyde, Benzaldehyde, o-chloro-, 2-Chlorbenzaldehyd, 2-Clorobenzaldeide, o-Chloorbenzaldehyde, USAF M-7, 2-chloro-benzaldehyde, o-Chlorobenzenecarboxaldehyde, 2-Chloorbenzaldehyde, 2-chloro benzaldehyde, NSC 15347, 2-Chlorbenzaldehyd [German], o-Chloorbenzaldehyde [Dutch], 2-Chloorbenzaldehyde [Dutch], 2-Clorobenzaldeide [Italian], CCRIS 5991, HSDB 2727, FPYUJUBAXZAQNL-UHFFFAOYSA-N, EINECS 201-956-3, AI3-04254, 35913-09-8, Benzaldehyde, chloro-, 6-chlorobenzaldehyde, o-Chloroformylbenzene, ZINC01706909, OCAD, 2- chlorobenzaldehyde, 2-chlorobenzenaldehyde, (2-chloro)benzaldehyde, PubChem16208, (2-chloro) benzaldehyde, AC1L1NRP, AC1Q3HJI, UNII-QHR24X1LXK, WLN: VHR BG, DSSTox_CID_4764, QHR24X1LXK, AC1Q6Q8W, DSSTox_RID_77522, DSSTox_GSID_24764, SCHEMBL97422, KSC448G6J, MLS001056242, Benzaldehyde, chloro- (9CI), ACMC-209r45, 124974_ALDRICH, ORTHO CHLORO BENZALDEHYDE, CHEMBL1547989, 23470_FLUKA, CTK3E8364, MolPort-000-871-203, BB_SC-6736, NSC15347, STR00143, Tox21_200373, ANW-39411, AR-1I2030, BBL010376, NSC-15347, SBB040228, STL146016, AKOS000119188, LS-1903, MCULE-3209883078, NSC 174140, RP20642, RTR-032822, ZF10003, CAS-89-98-5, NCGC00091218-01, NCGC00091218-02, NCGC00257927-01, AJ-30674, AK-44788, AN-24181, CJ-28887, KB-22799, SC-18116, SMR001216556, KB-229283, ST2409925, TR-032822, FT-0611908, FT-0611909, FT-0658390, ST50213378, 32069-EP2272517A1, 32069-EP2298777A2, 32069-EP2305629A1, 32069-EP2305679A1, 32069-EP2311816A1, 3B4-0429, I01-5974, I14-7353, InChI=1/C7H5ClO/c8-7-4-2-1-3-6(7)5-9/h1-5
PS 1145 dihydrochloride, CID6996, c0561, C059341, 1049743-58-9, 956-05-8