Document G5YLJaxvm1NOdX30e1qjadjYV

E. I. DU PONT DE NEMOURS & COMPANY KREBS PIGMENTS DEPARTMENT 256 VANDERPOOL STREET NEWARK, NEW JERSEY Copy No. / Period Covered: NEWARK PLANT PIGMENT COLOR RESEARCH REPORT Progress Report Synthesis of 3j36~4ichloybe2i&Ane hydrochloride M&rch-Juoei, 1944 FILE: DATE: 7-15-44 122,41 IN IV ; <i !\ NJBS3S N37958 Serial Ho, KN-44-48 Copy Ho. 1 Copy to: #1 - numerical File 2 - Research Office (122.41) 3 - Library File (122.41) 4 - Or. Ivan Gubelmann, Orchem 5 - Imperial Chemical Industries. Ltd. 6- * I* *7 _ n n a 8 - Mr. C, H. Ruppreeht, Wilmington (ICl File) mma p l a h t PIGMENT COLOR RESEARCH REPORT Progress Report Titles Synthesis of 3*3'-dichlorbenzidine hydrochloride Period Covered? March-June, 1944 SUBMITTED BIS APPROVED BZs DATE SUBMITTED: 7-10-44 DATE ISSUED: 7-15-44 DUP050149845  " 41 " mm >S%W;tliiortwi*idi** ltd to a short loirestigfttiO of the if lWLs intermediate from - i**ni%ro.*aj^or*beseae. It wa# known that other piicsent faeturers had alre&ity syitheaia their own inter mediate*, since Grebe was i*M* to produce more than was retired for their- am need stf*w'1fcNNitartNMr* of *lithosol* fellow "G CcMhutantML The purpose of- this investigation was to gather sufficient information to detormih# whether we should undertake the- manufacture of 3,l-dldiXri^sidle at Bewark. the meet common coiMaegtlel praetloe for the synthesis of 3,3*-diefclorbensidin from ortp^ltro-cl^or-heiiaene Involves a reduction of the nltro compound trith sine dust In alkaline medium, end the hydras compound formed thereby is subsequently rearranged by the-" action of mineral sold# This reduction may be carried out in alcohol solution (Reference l), but the one attempt made in this laboratory to follow this procedure met with very little success* A much more commonly used method requires solvent naphtha as the reaction medium (instead of the alcohol of the earlier method), the other steps in the synthesis being essentially the same as those of the original method. The naphtha process Is currently used by Orchem (Reference 2), snd the method of preparing bensidine from nitrobensen by this process is described in considerable detail in the literature (Reference 3). The method giving the most promising results in the current laboratory study was based essentially on the bensidina process described in the literature. The procedure as currently practiced at Orchem is rather complicated and requires special equipment not presently available at Bewark* Among the features of the Dyeworks procedure which would necessitate significant capital expenditure if we were to undertake manufacture at Rework are* 1. As emulsion of the solvent naphtha with water Is formed at one stage In tide process and special handling and treatment are required to break this emulsion. 2. Since solvent naphtha has a relatively low boiling ?ooinprte, vaennteefxficceisesnivtewloastesre-csooolfedtheconsdoelvnesnert is necessary during the reduction and subsequent rearrangement. 3* A distillation apparatus is required for recovery and rectification of the naphtha. 4. Owing to the flammability of the solvent, special pre cautions to guard against fire hasards are necessary. DUP050149846 Seme of the objectionable features of this procedure hair* bees circumvented is the laborailry W substituting per-ehlorethylene (manufactured by the Elefcem Department) for the solvent naphtha. The adiantages of this solvent over naphtha ares 1* It does not form a stable emulsion with water, and consequently no spooial precautions and treatment to break m emulsion are neoessary. 2. Since the solvent has a relatively high boiling point a water-jacketed condense? is not necessary and an efficient air condenser would probably be adequate to minimise losses through vaporization during the reaction, 3. Since the solvent is not s&selble with water it is readily recovered by simple gravity separa tion from the mother liquor* Rectification of the recovered solvent is not neoessary to permit its reuse in a subsequent run* 4. this solvent is non-flammable, and consequently no fire hazard exists. However, efficient ventilation Is necessary since the vapors thereof are known to exert an undesirable physiological action. Details of the laboratory process are described in the appendix. Ho extensive variable studies or yield studies were made. The objective of the current study was accomplished when It was shown that material satisfactory for use in our new Benzidine Yallow -2008 could be made by this method# As has already been indicated the only methods success fully applied in the laboratory for the synthesis were those using either solvent naphtha or per-ehlorethylene as the solvent medium. Modifications, which mot with little or no success that were studied included the following 5 1. Use of alcohol as the medium* 2* Use of 50j alcohol. 3# Use of water with Duponol WA as the dispersing agent. It was clearly shown in this study that adequate washing of the Intermediate with water or an aqueous saline solution is necessary to assure a product of satisfactory quality* An impurity which is water soluble is formed in the dichlor-benzidine hydrochloride, and if this is not removed its presence is detected in the -2000 pigment prepared therefrom by the follow ing characteristics: DU P050149847 4 M&sston * light at - mm and green Oil Bleed * markedly Inferior lightfaafeness - slightly inferior It Is quite likely that ttoe laeietaaties o_; insufficiently washed intermediates are due to the presence of orthoehlor-*ahillne hydrochloride as m impurity, the livelihood of this possibility was demonstrated by adding known aaownts of rtho-imler-aniline to satisfactory diehlerbemaidSn and chaining the same deviations in tinctorial and fastness properties from standard K-2008 as was obtained by inadequately washed intermediates. mmam 112 grams artho-altrochlor-bensene 500 cc per-ehlorethylene 7.2 g. canstie soda 100$ (as 50$ aqueous sol.) 15 ec water 152 grams sine dust (reagent quality) Stir and heat to 85-90C on a water bath. Ijldd intermittently in small portions} Maintain temperature at 85-90C until reaction is complete. Endpoint* eolor changes from deep red to straw color. Filter the hot reaction mixture and pour the filtrate with good stirring 112 grams hydrochloric acid 100$ (310 ce of 0.362 grams per ec) Beat to 40-50C. on a steam bath and continue stirring for 2-3 hours. Cool, filter, wash with small portions of per-chlorethylene and with successive portions of water or aqueous saline* Average Yield (based on nitrite value) ** 65-70$ of theory. Average Recovery of crude per-chlorethylene 70-75$. DUP050149848 5 Hotebook #1095. Bxpta. 1-16 inclusive. 1. P. Goto - Ber. 21 3552 (1900) 2. Letter A. Siegel to S, R, Allen (June 27, 1944) Subjects "Dyeuorks 3,3,~dichlorbenzidio process end equipment19. Report of visit to Dyevorks of March 16, 1944. 3. H. 1. Fierz-David and L. Blangey Farbenchemie 4th Ed, (1938) pp. 81-2 (Julius Springer, Fienna). DUP050149849