4- Tolualdehyde

Set up the apparatus depicted in Fig. IV, 118, 1 in a fume cupboard. The narrow wide-mouthed reaction vessel A has a capacity of about 250 ml. and is equipped with a rubber stopper carrying a mercury-sealed 

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FLUORINECOMPOUNDS,ORGANIC - FLUORINATED AROMATIC COMPOUNDS] (Volll) o-tolualdehyde [529-20-4]... 

Whereas the above reactions are appHcable to activated aromatics, deactivated aromatics can be formylated by reaction with hexamethylenetetramine in strong acids such as 75% polyphosphoric acid, methanesulfonic acid, or trifluoroacetic acid to give saUcylaldehyde derivatives (117). Formyl fluoride (HCOF) has also been used as formyl a ting agent in the Friedel-Crafts reaction of aromatics (118). Formyl fluoride [1493-02-3] in the presence of BF was found to be an efficient electrophilic formyl a ting agent, giving 53% para-, 43% ortho- and 3.5% meta-tolualdehydes upon formylation of toluene (110). 

Continuous-Flow Stirred-Tank Reactors. The synthesis of j )-tolualdehyde from toluene and carbon monoxide has been carried out using CSTR equipment (81). -Tolualdehyde (PTAL) is an intermediate in the manufacture of terephthabc acid. Hydrogen fluoride—boron trifluoride catalyzes the carbonylation of toluene to PTAL. In the industrial process, separate stirred tanks are used for each process step. Toluene and recycle HF and BF ... 

Terephthalic acid has been obtained from a great many /)-disubstituted derivatives of benzene or cyclohexane by oxidation with permanganate, chromic acid, or nitric acid. The following routes appear to have preparative value from />-toluic acid, />-methylacetophenone,2 or dihydro-/)-tolualdehyde by oxidation with permanganate from f>-cymene by oxidation with sodium dichromate and sulfuric acid from />-dibromobenzene or from /i-chloro- or -bromobenzoic acid by heating at 250° with potassium and cuprous cyanides and from />-dibromo-benzene, butyllithium, and carbon dioxide. ... 

The distillate, which may contain a small amount of a-tolualdehyde, is collected and used for the subsequent extraction. 

The carhonylation reaction of toluene with carhon monoxide in the presence of HF/BF3 catalyst produces p-tolualdehyde. A high yield results (96% based on toluene and 98% based on CO). p-Tolualdehyde could be further oxidized to terephthalic acid, an important monomer for polyesters ... 

The apparatus consists of a 3-]. three-necked flask fitted with a mercury-sealed mechanical stirrer, a reflux condenser, a dropping funnel, and a thermometer which reaches almost to the bottom of the flask. Five hundred grams of potassium hydroxide pellets (85 per cent potassium hydroxide) (7.5 moles) and 750 cc. of commercial absolute methyl alcohol (free from acetone) are placed in the flask and stirring begun. The bulk of the alkali dissolves in a few minutes, with the evolution of heat. The flask is now surrounded by an ample cold-water bath, and, when the internal temperature drops to 6o°, addition of a mixture of 360 g. (353 cc., 3 moles) of -tolualdehyde (Note 1), 300 cc. of formalin (3.9 moles) (Note 2), and 300 cc. of absolute methyl alcohol is begun at such a rate that the internal temperature remains at 60-70°. This addition requires about fifteen minutes. The internal temperature is then maintained at 60-70° for three hours, after which the reflux condenser is replaced by a downward condenser, and the methyl alcohol distilled with the aid of a brine bath until the internal temperature reaches ioi°. Nine hundred cubic centimeters of cold water is then added to the warm residue, and the mixture cooled. The resulting two layers are separated at once (Note 3), and the aqueous layer extracted with three 200-cc. portions of benzene. The combined oil and extracts are washed with five or six 50-cc. portions of water (Note 4), and the combined washings extracted... 

A technical grade of />-tolualdehyde, obtained from Fritzsche Brothers, New York, New York, was found satisfactory. 

Sterically bulky 3,3 substituents reduced the enantioselectivity, while coordination between La and O atoms of ortho-substituents improved ees. 6,6 -diphenyl-BI-NOL gave the best results (69% ee for para-tolualdehyde) it was proposed that the phenyl substituents affected the Lewis acidity of the catalyst via electronic effects. With this catalyst, ee and yield depended strongly on solvent, THE being the most... 

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