U +4Hnose-—' O+3HN02+NOB+NH4NO2
Total Page:16
File Type:pdf, Size:1020Kb
2,899,465 atent 1C6 Patented Aug. ll, 1959 1 2 manner is oxidized by nitric acid and it is_'believed that 2,899,465 this reaction proceeds as follows: TRICHLOROBENZENE COMPOUNDS AND THEIR PRODUCTION Theodore A. Girard, Wayne Township, Passaic County, and David X. Klein, Upper Montclair, N.J., assignors 01 to Heyden Newport Chemical Corporation, a corpora tion of Delaware 00011 10 No Drawing. Application March 21, 1955 01 01 ’ ‘ Serial No. 495,781 + H1803 + 4HNO1 +501 6 Claims. (Cl. 260-523) C1 In accordance with the last mentioned reaction each mole The present invention relates to the production of tri 15 of the thiosulfuric acid compound requires 4 moles of chlorobenzoic acid and is primarily concerned with the nitric. acid. However, if the trichlorobenzyl thiosulfuric production of 2,3,6-trichlorobenzoic by the oxidation with acid is formed in situ'from' the trichlorobenzyl sodium nitric acid of one of the novel compounds, 2,3,6-tri thiosulfate, then the stoichiometric amount of nitric acid lchlorobenzylamine, 2,3,6-trichlorobenzyl sodium thio is 5 moles per mole of starting material. The foregoing sulfate, 2,3,6-trichlorobenzyl thiosulfuric acid or di(2,3,6 20 description refers to sodium thiosulfate and it is to be trichlorobenzyl) sul?de. understood that other alkali'metal thiosulfates may be Benzylehloride having either no nuclear chlorination used in the same manner. or nuclear monochlorination can be oxidized With potas The sul?de'can be readily prepared by reacting 2,3,6. sium permanganate to the corresponding benzoic acid. trichlorobenzyl chloride with alkali metal sul?de. This Dilute nitric acid can be used to oxidize benzylchloride 25 reaction may be represented by the‘following equation: to benzoic acid but concentrated nitric acid tends to eifect nuclear nitration. Trichlorobenzyl compounds enter into OHgCl CH2 . S-————CH2 reactions involving the benzyl side chain with relatively great dif?culty and this is especially true of the 2,3,6-tri chlorobenzyl compounds, for example, 2,3,6-trichloro 30 benzyl chloride.’ Thus, While, 2,3,6-trichlorobenzy1 chlo ride can be readily formed from 2,3,6-trichlorotoluene, This sul?de can be oxidized upon heating with nitric acid such a route for preparing 2,3,6-trichlorobenzoic acid to form the corresponding ben‘zoic acid and it is believed presents serious difficulties. We have discovered that 2,3,6-trichlorobenzyl chloride 35 that this reaction proceeds as follows: can be converted to 2,3,6-trichlorobenzylamine, 2,3,6 trichlorobenzyl sodium thiosulfate or di(2,3,6-trichloro benzyl) sul?de in good yield and then either one of these last mentioned compounds can be reacted with concen trated nitric acid to form 2,3,6-trichlorobenzoic acid with 40 out e?’ecting substantial ring nitration. ' The 2,3,6-trichlorobenzy1 sodium thiosulfate can be formed by reacting 2,3,6-t1'ichlorobenzy1 chloride with sodium thiosulfate. It is believed that this reaction pro ceeds as follows: 45 CHzCl CHQSS O3Na Thus, each mole of trichlorobenzyl sul?de requires 7 moles of nitric acid. C1 C1 C1 ~Cl The 2,3,6-trichlorobenzyl amine can be formed by re + Nagsgog -——--P + NaOl 50 acting trichlorobenzyl chloride with ammonia in the C1 ——C1 presence of a solvent and, this reaction may be represented by the following equatiom‘ This sodium salt can be readily converted to the acid ‘ 011,01 oniNn, form, trichlorobenzyl thiosulfuric acid, by a strong min 55 or 01 V. 01 _o1 eral acid such as H2SO4,HCl or HNO3 in accordance with + NH3 -—> I + H01 the following reaction using nitric acid: ' OHzSSOaNa CHZSSOaH The trichlorobenzyl amine can be oxidized with nitric I 60 acid and this reaction may be represented by the follow Cl- ~01 C1 C1 ing equation: + HNO; -———> + NaNO3 CH2NH2 00011 ~ C1 —C1 ’ 65 01 c1 ' Y ' > I ' i The trichlorobenzyl thiosulfurie acid produced in accord ance with the above reaction or produced in any other U C1 +4HNOsE-—'' . O+3HN02+NOB+NH4NO2 2,899,465 3 . 4. As shown, each mole of trichlorobenzyl amine requires product apparently was trichlorobenzyl sodium thiosul 4 moles of nitric acid. fate and after drying it weighed 120 g., a yield of 50% In the foregoing oxidation reactions, one mole of 2,3,6 based on the trichlorobenzyl chloride charged. trichlorobenzyl thiosulfuric acid or 2,3,6-trichlorobenzyl The 120 g. (0.38 mole) of product obtained above was amine requires 4 moles of nitric acid while one mole of charged into a reactor along with 430 g. (4.8 mole) of di(2,3,6-trichlorobenzyl) sul?de requires 7 moles of nitric 70% nitric acid over a period of 45 min. On the assump acid. These molal ratios are the stoichiometric amounts. tion that 0.38 mole of the'nitric acid reacted with the Preferably an excess of'nitricTacid is‘ used't‘o increase the trichlorobenzyl sodium thiosulfate, then the molal ratio yield. Large excesses of nitric _acid,mayi,be used. As of trichlorobenzyl thiosulfuric acid to nitric acid was used herein when the term “nitric acid” is accompanied 10 0.38 :4.42 or about 1:12. The charge was heated to re?ux by a percentage ?gure, the ?gure refers to the percentage and held at this temperature for 8 hours. The reaction of nitric acid present in the material used with the re mixture was cooled and ?ltered to separate the crude mainder being water plus the small arnount of impurities trichlorobenzoic acid. This crude product was puri?ed present in commercial nitric acid. Thus,‘ 70% nitric by dissolving it‘ in'dilute-aqueous sodium hydroxide and acid” refers to the fact that the nitric acid used contained 15 then reprecipitating the trichlorobenzoic acid by acidfy about 70% nitric acid and 30% water. Nitric acid of ing the solution with hydrochloric acid. > In ‘this manner other concentrations may be used ‘with the preferred con there was obtained 24 g. (26% yield based on the tri centration being in the'rari‘ge of ‘BO-85%. chlorobenzyl sodium thiosulfate) of trichlorobenzoic acid Example I containing a high percentage of th'e'2,3,6-isomer. 20 Example III Chlorine gas may be passediover the surface ofa body of mixed‘ isomersv of‘trichlorotolue‘ne ‘at "about 205-210° The following materials were charged into a reactor C. until the weight increase corresponds to the theoretical equipped with a re?ux condenser: as determined in accordance ‘with the‘ following reaction: 173 g. (0.75 mole) trichlorobenzyl chloride (mixed iso 25 mers) I (‘3113 (‘513101 66 g. (0.6 mole) potassium sul?de 450 ml. ethanol The mixture was re?uxed for 72'hours, drowned in cold water and the sul?de oil was separated and washed with The mixture’ is then blown with air at 100° ‘C. to remove water. Then 167 g. (0.42 mole) of this di(trichloro any free chlorine and hydrogen chloride present.‘ In this 'benzyl) sul?de was placed’in’a reactor with 810 g. (9 manner trichlorobenzyl chloride ’ may be obtained in moles) of 70% nitric acid. The‘ mixture was heated and re?uxed‘for 6 hours and'then drowned in cold water. 100% yield based on the trichlorotoluene charged. The The crude was separated by ?ltration and'puri?ed by dis isomer or isomers present in the product is the same as solving-in aqueous sodium ‘hydroxide followed by re the isomer or isomers of the starting’ material. In this precipitating with hydrochloric‘ acid. The separated tri particular case a mixture of trichlorotoluene isomers was chlorobenzoic acid which was a'r?ix'tur'e of isomers con~ used in which a major portion consisted of 2,3,’6-trichloro taining a high'lper‘centage of the 2,3,6aisomer weighed toluene and a minor portion consisted of a mixture of the '33 g., 19% yield‘bas'ed ‘on the di(trichlorobenzyl)sul?de. 2,3,4-isorner, 2,3,5-isomer, _ 2,4,5-isomer and 2V,‘4,6_-is'_omer. Accordingly/the trichlorobenzyl chloride was a mixture Example IV of the corresponding isomers in the same‘ proportions. Two hundred thirty-one grams‘ of' mixed isomers of All of the various isomers of trichlorobenzyl chloride trichlorobenzyl.chloride,‘ like that of Example I, were can be prepared in any suitable manner and may be pre charged into'a reactor and their therewas' slowly added pared, for example, by the s'idep'chain chlorination ‘of a solution of 255g. (15 moles)'of"ammonia gas dissolved isomers of trichlorotoluene. While the present invention in 2 liters of methanol while‘cooling‘ to maintain ‘the is primarily concerned with the'production‘of 2,3,6-tri temperature below 20° C. 'The'mixture was then stirred chlorobenzoic acid from 2,3,6-triclilorobenzyl chloride, at room temperature for 72 hours. The excess methanol the other isomers of trichlorobenzoic acid can be pre "and ammonia'were removed'under’ partial vacuum. The pared in the same manner. In general, the arrangement 50 residue was treated withi'200'g. of'40%‘sodii1m'hydroxide ofthe three chlorine atoms on the ring in the trichloro solution‘ and then‘ extractedwith two-one liter portions benz'oic acid are 'the sanie as ‘the arrangement in the start of ether. The combined extracts werejdriedt over anhy ing material. The trichlorobenzoic acids which do not drous sodium sulfate and then evaporated to dryness. contain the 2,6,-arrangement_are, if anything, more readily The product, ‘crude trichlorobenzyl amine, weighed 205 produced as these other isomers are more reactive. The g., a yield of 97.4% based on the trichlorobenzyl chloride spatial arrangement of the 2,3,6 isoir'ier renders it ‘less charged.