The Silver Salts of Tetrabromphenol Citation Steele, James P. (1918) The Silver Salts of Tetrabromphenol. Bachelor's thesis, California Institute of Technology. doi:10.7907/cjev-mb95. https://resolver.caltech.edu/CaltechTHESIS:07192024-224641502 Abstract No abstract. Item Type: Thesis (Bachelor's thesis) Subject Keywords: (Chemistry) Degree Grantor: California Institute of Technology Division: Chemistry and Chemical Engineering Major Option: Chemistry Thesis Availability: Public (worldwide access) Research Advisor(s): Unknown, Unknown Thesis Committee: Unknown, Unknown Defense Date: 1 January 1918 Record Number: CaltechTHESIS:07192024-224641502 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:07192024-224641502 DOI: 10.7907/cjev-mb95 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 16578 Collection: CaltechTHESIS Deposited By: Benjamin Perez Deposited On: 23 Jul 2024 17:02 Last Modified: 23 Jul 2024 17:08 Thesis Files PDF - Final Version See Usage Policy. 5MB Repository Staff Only: item control page

THE.SIS. The Silver Sal.ts o:f Tatrabrom:phenol. by James P. Steel.a. O:lass of Nineteen H'u.ndre d and. Eightee:n. Department of Chemistry. THOOOP OOLLEGE OF TE:mmoLOGY. Pasadena,. Oali:fo:rnia. 1918. Introduotion. B.efore l910 only one silver salt of 2-4-6 tribromphenol had been prepared. This salt was prepared by Purgotti 1 in 1886. In lSlO. Torrey and Hunter 3 of Harvard University. suoceeded in preparing two forms of the silver salt of tribrompbenol. a pink and a white variety, whioh they proved by analysis to be isomers. The form of the silver salt prepared by Purgotti was desoribed by him as an ora~ge yellow precipitate. The salt prepared by Torrey and Hunter wa s a white amorphous salt. These men prepared the white salt from a slightly arnrnoniacal solution of the sodium salt. They failed to find any ditferenoe in the behavior of the two salts. Two other oases in which two isomeric forms of the silver salts of the halogenated phenols occur have been named by Torrey and Hunter: namely, silver salts of tribromresoroinol monomethyl ether and of 3-4-6 tribromguaiacol. However, the red forms in both cases were very unstable and no analyses could be made of them. Hant~sch 2 working along these lines, confirms the observations of Torrey and Hunter and also added some other results. The sum of these results gives as a tot~l five halogenated phenols which were known to have existed in two isomeric forms of the silver ~alt, altho, as has been stated, it was not possible to prove this in every 2. oase because of the unstability of the pink form. Three of these have already been mentioned but will be given again for simplio-i ty. 1. 2-4-6 tribrornphenol. 2. 2-4-6 tribrornresoroinol rnonomethyl ether 3. 3-4-6 tribromguaiaaol. 4. tetrabromguaiao.ol 5. dibromoparaoresol. Hantz.sach also investigated many other halogenated silver salts and has pre-pared the following table, which has since been modified by later investigators. Silver Salts of: Chlorphenols. Bromphenols. o-m-p o.hlorophenol colorless p bromphenol colorless p iodophenols oolorle-ss 2-4 diohlorophenol oolorless 2-6 dibromophenol colorless 2-6 diiodophenol oolorless 2-6 dichlorocresol yellow 2-6 dibromo-p-oresol 2-6 diiodo-p- tetrachlorphenol yellow pentae:hlorphenol yellow Iodophenols. yellow colorless ore sol •colorless 2-4-6 tribromphenol 2-4-6 triiodo- colorless pink phenol oolorle 2s (yellow) 0 tetrabromphenol colorless (pink) 8 pentabromphenol colorliss (pink) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. a This salt has been prepared by the author. b This salt has bee-n prepared by Kemp. (11hesis, T.C.T. lffi. 7 a This salt has been prepared by Woollett. J.A.C.S. 38,2474 It has been shown by later investigators that this table is by no means complete. Kemp and Woollett have both add8d to it. and the author has prepared another salt of tetrabromphenol as indiaated. In view of these faats. a systematic: investigation of the silver salts of the halogenated phenols would be of value in determining the exist enoe of other isomeric forms. The silver salts of tetrabromphenol have been investigated by the author and the results are tabulated in the following pages. ·······~················ Discussion of Results. Only one silver salt of tetrabromphenol was described in the literature at the time this research was taken up . ·4- ~ Two forms of both tribromphenol 3 and pentabromphenol had been prepared. Torrey and Hunter showed these two forms in the case of t.ribromphenol to be isomers. Hantzsch describes t wo forms of the silver salt of 2-6 dibromo-pc.resol whioh were proven to be isomers. Hantzsch also describes two forms of the silver salt of pentabromphenol but one of these he thinks is the other form containi ng impurities.(pink) There was no apparent reason for beleiving so, however, since the pink salt retained its color after repeated recrystallization. It has since been shown by Kemp 5 in his work up6n pentabromphenol that the pink salt was an isomer of the white salt. Hantzsch himself pointed out that in the case of some of the other forms 4. of the isomeric silver salts that the transformation of one form into the other was accelerated by the presence of alcohol. He apparently failed to realize this possibility in the case of the higher phenols. The author has prepared two forms of the silver salt of tetrabromphenol and an ammonia addition product in which there are two molec.ules of ammonia for every atom of silver present. One of these silver salts is colorless. The other comes down as an orange yellow preaipi- tate but turns pink on drying. These two forms have been shown to be isomers by analysis. The results of these analyses are given in the following pages. By means of a few simple experiments and a study of the conditions under which the colored and the colorless forms of the silver tetrabromphenolates are formed has s'hown that the pink form is the unstable form and the white the stable form. The pink salt,waa prepared from a neutral solutio n of the alkali salt by the addition of silver nitrate, is readily tra nsformed into the white form by the addition of a few dr op s of dilute ammonia to the freshly prepared wet salt. The analysis of the two forms thus p re1)ar ed has shown them to be isomers, just as in the case where the white salt was prepared by the direct addition of the nitrate to the slightly ammon- 5. iacal solution of the alkali salt, of tetrabromphenol. In as much as some authors 6 have stated that the - oolored forms of some of these silver salts were probably due to impurities. it is worth while to state some reasons for beleiving that this is not true in the case of the silver tetrabromphenolates. In the first plaae-. sinc:e two isornerio forms of the silver salt have been prepared in the oases of tribromphenol and petitabromphenol, it follows from a consideration of the oorresponding properties of the phenols that there would be two forms of this kind in the case of tetrabromphenol silver salts. The tetrabromphenol used in this work was of a very high grade of purity (99.9-8%-99.80% pure)• as shown by analysis. It crystallizecl from alcohol in long silky white neeclles. absolutely free from color of any kind. The analyses of both the colored and the colorless forms agree with the theoretical percentages. Moreoger. the transformation of the colored form into the colorless form takes place without the liberation of any colored by-pr o,ducts . . . . .. .. .. . .. . . . . . . . . . . . . . . . . .... 6. Experimental .. Preparation of Tetrabromphenol. The method: of preparation of this acid from tribrom1 phenol and bromine, by heating at 17o 0 ~1so 0 for several hours in a combustion furnace, as outlined by Korner 7 ,is not at all satisfactory since it requires a great deal of careful attention, very pure products to start with, eto., and also the possible nuisance of the combustion tube breaking and discharging its oontents. Werner 8 pre pared tetrabromphenol by first making the body tetrabromcyolohexadienone by the addition of the necessary amount of bromine in a saturated aqueous solution to a solution of phenol in wate~. The resulting yellow body · is carefully dried and heated for some time with concentrated sulphuric acid at the melting point of the body, 118° a. The product is poured into water and the tetrabr omphenol se parated a nd purified. The aut hor failed to obtain any satisfactory results with this method. Orton and Ooates 9 prepared tetrabromphenol in one of their experiments by decomposing tetrabromodiazobenzene and obtained a tetr abromphenol whic h melted at 115° C. This method is a 'round-a-bout method of obtaining the tetrabromphenol since it requir e s the preparation of the diazo body to start with. and would proba bly never be 7. used where it is desired to prepare tetrabromphenol in a large quantity as it was in this research. The author prepared. tetrabromphenol by the direct bromination of tribromphenol in the presence of anhydrous 10 aluminum bromide, by a method similar to that of Bodroux for the preparation of pentabromphenol. The tribromphenol was carefully dried and fused in a side-necked flask over a water bath. Bromine (liquid) containing 2% of Al in the form of anhydrous aluminum bromide, was run into the fused mass, over a period of 8 hours, in order to insure complete bromination. Whe.n the theoretical amount of bromine had been added and just before the produot in the flask solidified 25% excess bromine was run in at once and the mixture shaken and cooled. The reaction between the bromine and the tribromphenol continues after the product has cooled just as well as i n the fused material, but it is necessary to fuse the tribrpmphenol in the beginning in order to have thorough mixing of the phenol and the Brt.,,,, : .. ,.: The product in the flask, which consisted mainly of tetrabromphenol with small amounts of tri- and penta- bromphenols an d bromine and alumi num bromide, was se parated from the flask by craaking the fla s k anay from it. after the pr oduct had beer. alowed to co ol and stand for several hours. ilesults of one bromination are as follows: 8. Tribrom_phenol taken .................... 108 gms. n Bromine used ...... . ................... . 66 Al uminum used •. ................... . ...... 1. 5 " Theoretical Yield .....................• 134 (crude inc l . Al ) Actual Yiel d ..... . ..................... 1 36 Yield pure product (m.p. 114°) . .. .. .. . . ti n 56.5 " The H13 r given off was absorbed in wa ter and t itrated with NaOE to determine the completeness of t he bromination. I!1rom the results of the titrati on the bromination was shown to be 95% complete. 1/5 of sample titrated. NaOH used ••...... .. ........ 62.0 c.c. Sample contains -IIBr ........ 25.1 gms . Theo ret ical ................ 26.4 " Bromina tion ............. .. • 95% The additional wei@1t of t h e crude tetrab romphe nol was b rom ine he l d in sus pens ion in the solid materi al. The pr oduct from the flask was le a ched wit h cold alcohol (95%) and later hea ted until all soluble matter was in solution. The solution was then boiled with charcoal (animal) refined, until on filtering, the resul ting solut i on was colorless. -The alcohol was then diluted to BO% and the pen tab romphen ol allowe d to C:'r;ystal1ize out. This was a very small amount. The solution was then diluted to 66% and the tetrab romphenol allowed to crystall- s. ize out. This carried a small amount of tribromphenol with it as an impurity. Several recrystallizations resulted in the production of long silky white needles of tetrabromphenol which were later analyzed to determine their purity. The tetrabromphenol thus separated was found to be 99.98%-99.80% pure. m.p. 114° C. Yield 56.5 gms. On another batch of the crude tetrabromphenol thus prepared, a series of experiments were made in an attempt to purify the crude product in a much simpler manner. since the purification by fractional rec-rystallization from alcohol is very difficult. It was thoueht that this might be possible by dissolving the product in sodium hydroxide, filtering off any impurities in t h e form of in s oluble matter and precipitating again by the addition of an acid. By virtue of the differences in smlubilities of the three bromphenols a se paration was e:x.i: ected. It was fou nd however, that no separation was effected, and a product was obtained which invariably melted at 78°-85°, far below th e melting points of the three bromphenols, 93°,lf0°,229.5° resp. Very little work wa s done upon the product thus obtained other than an attempt to separate it by means of fractional crystallization from alcohol. The product once obtained however, would not separate appreciably from alcohol in this manner, but gave the same product after repeated recrystallization. It was tr.oueh t thot the HaOH 10. might be acting as a catalys t i n th e .crese nc e of small amounts of tri- and ~enta- br ornphenols causing the reoH' action 1',oOHl)r 2 • tJr W I' ~ - C,,oe... 8 (fr + y to take place. There was very little to confirm this theory however since pu re tetrabromphenol was se parated fro m a s~lution of t h e s od ium salt wh ich had st ood for some time, and whi ch was p re_pa red by dissolvin g t he free acid in NaOH, by the addition of dilute HAc. Appar ently no reactio n of the type jus t mentioned had taken place • ............................. Preparation and .Analysis of the Two Silver Tetrabrom- - - - - - -- - - - phenolates. Preparation of The Anhydrous Pink Salt. As the sodium salt of t he acid tetrabromphenol is the most soluble of t he alkali salts, t he silver salt was prepared from a solution of this salt. 3 gms. of pure, dry tet r abromphenol (m.p. 114°C.) was treated with enough 1 N. NaOH to dis s olve and the solution diluted to 150 c.c. Dilute (.05 N) 3Ac was t hen ad ded until the solution was neutral. Th is condition was noticeable by a sli gr:t clouclijness of the solution due to the separation of the free acid caused by the additio n of a slight exces 2 of HAc. The soluti on was diluted to 300 c.c. 11. and one or t wo dro p s of silve r nit rate added to f r ee the soluti on of a ny chlori des or bromides whic h mi gh t be pres ent. The soluti on wa s then filtered thru a ver y hi gh gra de of filter paper until the re sulting solution was cle ar. This solution was diluted t o f our times its ori gi nal volume and enou gh 9 05 N. silver nitrate a dded to com- ple t ely pr e cipitate t h e tetrabromp henol present as the silver s~lt. This pr ecif itate wa s ora nge yellow. Dilute HAo was then added until t h e solution was sli ghtly acid. This was to p revent the se paration of any silver oxide in the preci p itate. The yellow preci pitate was very gelatinous.It was filtered on a Buchner funnel and removed to a 500 c.c. flask, HAc added and. skaken t o fiee from any silver oxide wh ich might ha ve been formed in the filtration.It was filtered a gain a nd removed to the flask. This time it was agitated wit h pure wa ter and Silt e red. The pr ecip itat e wa s su cked as dry a s po s sible an the fun ne l, removed t o a cle an poro us plate and plaaed in a cle an de sk to dry. It was removed some time later, having turned pink in the process of drying. and thorou ghly pulverized and given a final drving over phosphorous pentoxide, for several days. Analyses were made on it for silver, by th e met~ od of Kemp and Lucas 11 . iiesults of these analyses are given as follows: 12. No. Wt. Sample. Wt. Ag2S. %Ag deter. %Ag oalc from C:5HBr 4 Q1f\ 9 I. 0.2991 gm. 0.0720 g. 20.90 20.89 II. 0.4060 II 0.0976 IT 20.94 20.89 III. 0.3141 " 0.0756 Tf 20.9 6 20.89 •••••••••••••••••••••••••••• Preparation of the Vfuite Amorphous Salt. As in the pre paration of the pink salt, this salt wa s prepared from a solution .of the sodium salt . 3 gms. of the puret dry salt (m.p. 114 °) was dissolved in the requisite amount of 1 u. NaOH and the solution diluted to 150 a.c. Dilute HAc was then added until the solution was neutral. One or ttwo dro ps of silver nitrate were then added to free the solution from any chlorides or bromides which might be present and the solution diluted to 300 c.c. and filtered thru a high grade of filter _p a1 er until the solu t ion corning thru was absolutely clear. This solution wa.s made slightly ammoniac-al with dilute ammonium hydroxide and diluted to four times its original volume. Enough .05 H. silver nitrate was then added to oompletely precipitate the tetrabrornphenol p resent as the silver salt. This salt came down snow white. (It might be slightly b~own due to the separation of a small amount of silver oxide. If this should happen, HAc should be added until the color is destroye d ). HAc was added anyhow as a preventitive toward any separation of the kind indicated. until the solution 13. was faintly acid. The white amorphous silver salt prepared in this manner was filtered on a Buchner funnel and transferred to a 500 c.c. flask. The salt was thor~ oughly agitated with dilute RAc. and refil tared. It was again removed to the flask and skaken up with water.Finally the precipitate was sucked as dry as possible on the funnel and transferred to a clenn porous plate in a olean desk to dry. Later the s r1 l t was removed, thoroughly pulverized and given a final drying over phosphorous pentoxide for several days. Analyses were made upon it for silver as before. The results of these analyses are as follows: No. Wt. Sample. %Ag. Calo from C'6RBr 4 o~ I. 0.3147 gm. 0.0768 gm 20.97 20.89 II. 0.4998" 0.1205 " 20.99 20.89 III. o.3593 ,. 0.0868" 20.80 20.89 ••••••••••••••••••••••••••• Preparation and Analysis of the Yellow Ammonia Addition Product. The ammonia addition salt was prepared by treating the ~..,-,-;- st ill moist silver salt (either oolor) with, ._ enough cone. ammonium hydroxide to dissolve it. An excess p:revents the precipitation of the ammonia salt. Very soon after the solution of the silver salt, the ammonia addition salt precipitates from the solution as a cream yellow amorphous salt. 14. About 5 grns. of the freshly prepared pink silver salt were treat e d i n the manner outlined above. The ammonia a ddition product which separated was filtered on a Buchner funnel and placed in a dessicator in an atmosphere of ammonia over soli d sodium hydroxide to dry. After several days the salt was removed and analyzed for ammonia by the Kjeldahl method. The results of this s et of analyses is given a ~ follows: lfo. Wt. Sample. o.c. HCl used 0.0252 N. I. 0.8610 60.21 6.21 II. 0.8015 56.10 6.23 \ Previous to the analyses a portion of ammonia salt was weighed out onto a watc h glass and dried in an electric oven for l hr. The salt lost weight corresp onding to 2(NH3 ) Wt. Salt takem ............ 0.8473 gms. vVt. After Heating ••........ 0.7947 n Loss Ammonia •••••......... 0.05 26 ~ • . ~ ~ .Ammonia Lost ............ 6.21~ " Samples of the dried white and pink silver salts were placed in an atmosphere of strong ammonia for several hrs. to see if they would absorb ammonia. They would not absorb ammonia as was noted by weighing them occasionally. The salts were dampened and the process repeated with the same results. Concentrated ammonium hydroxide failed to have any effect on the dry salts. Before drying the salts 15. they are very readily acted : upon, but after drying the converse is true. The ammonia salt on being heated gives rise to the white silver salt. Wt. Sample Taken ........................ 0.3578 gms. After 1 hr ••....•••.....••.....•... _ 0.3581 After 4 hrS ......................... 0.3585 After 12 If .......................... O.Z584 After 24 " .......................... 0.3585 ,, If " " This is data from the pink salt which should be the most active since it is the unstable form. The small ad ditio.n to the weight is due to entrainelt ammonia in the salt . ............................. Other Salts of Tetrabromphenol. Other metallic salts were prepared from neutral solutions of the sodium salt with the following results. Some of these salts so prepared act as tho there are isomeric So,/fs forms of other metallic~than silver. Colored Amorphous Salts. a c·o ++ light pink White Arnerphous Salts White Crystalline Salts. Pb++ K+ b au•+ chocolate brown a ca++ H_g ++ light yellow ~n++ Ni++ light green Sb++ :M'g++ ++ cream yellow ++ ' Fe dark yellow Sn++ Ca As+++ Ba Hg+# light yellow ++ light pink Mn Bi+++ Fe O +++ cu+ light brown Sn ++++ + NH4 '" Sr ++ ++ .++ Li 16. With ammonium hydroxide some of these salts undergo changes as follows: au++ - Preoipitate turns very light blue and finally with more NH 4 0H dissolves giving complex oopperGv ammonium salt solution. Hg+ - aompletely dissolves and sli ghtly decompos es giving a small amount of metalLic mercury. Fe++_ Preaipitate turns red.(Prob,. due to some Fe(OH) 3 ) +++ Fe - Turns dark green and then up,n standing turns dark brown.· ++ Hg • - Turns oreamy white. +++ Bi Mn ++ ' - Changes to amorphous orange yellow salt. ' - Changes to creamy brown precipitate . ......................... a Light pink crystals • . b Turns blue on standing. 0 Turns orange on standing. d Preci_pi tates light blue crystals on being exposed to sunlight for a ·1ong time . ............................ Eithe:r Baker's "Analyze-dlf or a high grade of Kahlbaums chemicals were used throughout this thesis. ~, Tetrabromphenol ~ Alkali Salt Solution c,1-koH;Nl-/-,0H; Heed Yellow .Amorphous__;; ________ White .Amorphous Addition Product . Lemon Yellow Solution. Reference Sheet. l. Gazz.• Chim. Ital. 16, 527 (1886) 2. Ber. 40, 4332 (1907} 3. Torrey and Hunter, Jour, Am. Chem. Soc. 33,194-205. 4. ffantzsch, Same as 2. 5. Kemp, Thesis, Throop Collage of Tea·hnology. 1917. 6. Hantzsoh, No. 2. Also Fuicht and Lieben, Bull.Soc. Chem. 7. K8rner, Annalen, 137,209. 8. Jour. der russ. Chem. Gesell. 18, 105. Q} ,,e ('('I • 9. Jour. Lend. Soc. 9,1 , 51. 10. Oomp. Rend. 126, 1282-85(1898) 11. Jour. Am. Chem. Soa. 39-9-2074.