A SUBSTITUTE FOR TANNIN By ABE MORRIS SAX THESIS FOR THE DEGREE OF BACHELOR OF SCIENCE IN CHEMICAL ENGINEERING COLLEGE OF LIBERAL ARTS AND SCIENCES UNIVERSITY OF ILLINOIS 1921 / 92 / Sa.37 - UNIVERSITY OF ILLINOIS July_8 I92 l__ THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Ab e_ Morr is _ Sax ENTITLED _A_ _Su.bsiii.ut_e _ Hqz. - Yannin IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE degree of Bachel_pr__of Approved : HEAD OF DEPARTMENT OF Ciiejulutry. Digitized by the Internet Archive in 2016 https://archive.org/details/substitutefortanOOsaxa Acknowledgement . The writer wishes to acknowledge indebtedness to Dr. Roger Adams for his interest and valuable advice to- wards this work. 1 . Table of Contents. pages I. Introduction 2 II. Historical III. Theoretical 5 IV. Experimental 7 1. Cymene Sulfonic Acid 7 Preparation, tests, and tanning action. 2. Condensation of Cymene Sulfonic Acid with Formaldehyde 8 Preparation, tests, and tanning action. 3. Other substances 10 V. Summary and Conclusion 10 VI. Bibliography 12 , >: 2 . Introduction. Within the past decade certain definite advances have been made in th6 manufacture of leather. One of these has been the use of synthetic tanning materials, by means of which it has been pos- sible to secure a better quality of leather in much less time. These synthetic tannins are prepared from rather expensive phenolic bases. Incidentally , the cost of the finished product has been comparitively higher than the natural tannins. Because of this there has been a tendency among leather r anufacturers to avoid using them. If it is possible to produce a product which can compete with natural tannins, it is quite obvious that tanners will avail them- selves of the opportunity. The object then, is to utilize an in- dustrial waste product in the manufacture of a substitute for tan- nin. Cymene , a by-product of paper manufacture, is the substance used in this work. . « ■ • .* ■ . . . . v’ o. Historical . 1 In 1906, M. Hierenstien produced from a condensation of py- rogallol and formaldehyde a substance, which in water solution . precipitated gelatine. He obtained a leather which was more or less satisfactory, but no attempt was made to utilize the compound on a commercial basis. (It is to be observed that both pyrogallol and formaldehyde precipitate gelatin from a water solution and have tanning action on hide.) 2 L. Meunier and A. Seyewetz obtained leathers by the use of an alkaline solution of hydroquinone ; quinone behaved similarly. In both cases the leathers were white in color, tough yet pliable and without weight. The following compounds were found to render gelatine insoluble;- phenol, resorcinol, orcinol, hydroquinone , pyrocatechin, gallotamiic acid, pyrogallol, p-amincphenol , chlor- ophenol, pioric acid, mono-chlorhydroquinone , quinone , and the mono- and di sulfonic acids of B-napthol. 3 Formaldehyde tannage was produced by U. J. Thuau ; but the leather after a month lost its firmness, became brittle and hygro- scopic. This is probably due to the oxidation of the formaldehyde to formic acid. However, good results were obtained in using formaldehyde as a preparatory bath. 4 Emil Fisher and X. Freu&enberg found that on the hydrolysis of purified tannin ( gal lo tannic acid) with five percent sulfuric acid, ninty percent of gallic acid and from seven to eight percent of dextrose was obtained. From this they concluded that tannin was an ester of glucose with five molecules of meta gallic acid. He prepared a penta-tricarbomethoxygailoyl glucose compound . . .. . • . . ; . . . • . . . * 4 which has the following formula p — — o- — CHOR-CHOR-CHOR-GH-CHOR-CHgOR 0 ^OGOOGHg where R» -C < >OGQOCHg ^-OCOOCHg This was saponified with ITaGH, forming the pentagalloyl glucose. This compound was similar to tannin in every respect except that it was not optically active as is the natural tannin. Due to the very difficult and complicated method of preparation, it is impos- sible to make the tannin commercially. 5 E. Stiasny produced a synthetic tanning material hy sulfonat- ing crude cresylic acid and forming a condensation product with one mole of formaldehyde to two moles of cresylic acid. The excess acid was neutralized with Da OH. The soluble product obtained was 6 called Herodol-D, which gives a white, firm, and pliable leather. Like the quinone and formaldehyde tannages, the leather lacked weight. The IJerodol-D is recommended for use (1) as a preparatory hath, (2) in combination with natural tannine, and (5) as a bleach- ing agent. After Stiasny's work, there appeared quite a number of these synthetic compounds, which were called Syntans. All of these are condensation products of formaldehyde and some sulfonic acid, dif- fering in detail of manufacture and in base of sulfonic acid. Two which differ from the rest are, (1) condensation products obtained by heating phenol or eresol sulfonic acids under mild 7 conditions. Excess acids neutralized. Ho formaldehyde is used, and (2) condensations with formaldehyde, of napthalen6 sulfonic . • . . . . 5 8 acid . Theoretical . Tanning consists of converting the raw, putrescible hide in- to a strong, pliant, firm, and imputrescible substance, which is unaffected to a degree by water. Any material which will so convert the hide may be regarded as a tanning agent. The hide in itself consists of an epidermis, (the outer lay- er) and the dermis, which is composed of two distinct parts, the collagen and the corium. The collagen is very readily transformed into gelatins on boiling, whereas a more vigorous boiling is neces- sary to convert the corium into gelatine. The corium forms the fibrillar structure noticeable in leather. In the preparation of upper leathers, the collagen is easily dissolved away due to en- zyme action; the corium is also affected, but not dissolved. 9 L. Msunier concludes that tanning consists of the following phenomena occur in? simultaneously : - I. Chemical Action It is generally accepted that the hide substance is of a protein nature, and has somewhere in its molecular structure an amino group. Whether it is a primary or secondary amino group is not definitely known. Usually the simplest formula to desig- nate hide substance is R-NHo . Another formula, with a secondary amino group is:- NK / R . . ?his is supposed to interact with water to give:- m / R \ f H *° HEoR-COOE G-0 6 . 10 Ileunier and Seyewetz demonstrated that aqueous solutions of pure phenols do not render gelatine insoluble, but that their oxi dation products do. R-IIHg -f 2C..H 4 0 2 > R-N(C 6 H 4 0 2 ) 4 CgE 4 (0H) 2 or 2R-L T Hg + 3C 6 H 4 0 2 > 2C6R 4 (0H) 2 4 C 6 H 4 0 2 ( E-il ) 2 With formaldehyde the following reaction apparently occurs :- 2R-EE 2 4 C-S 2 0 > R-1?=CH 2 4 EgO The resulting compounds are of a colloidal nature and compar- atively stable. II. Adsorption By the action of the gel constituting the swollen hide fibres, the colloidal tannin is precipitated on the surface of the fibres. This results in a concentration of the tannin solution around the fibres, which aids in adsorption. III. Transformation A part of the precipitated tannin is transformed from the reversible to the irreversible , insoluble form by the action of oxidation, hydration and polymerization. This transformed tan- nin is called "Bloom”. IV. Osmotic Phenomenon. Due to the action of adsorption, transformation and chemical reaction, tannins are precipitated on the corium fibres. As result, osmosis occurs and the hide fibres are dehydrated, leaving an increasingly marked formation of fibrilliar structure. ' i ' * - - • , * . . * Tannins which show all four phenomena may he classed as true tannins, while those that do not, as Alum tannage, e.g., may he considered as pseudo-tannins. Experimental. Preparation of Gyrnene Sulfonic Acid. The cymene received was in an impure state, having about fif- ty percent of water and other impurities with it. On standing, the water separated into a distinct layer and was removed by means of a separatory funnel. The pure cymene was distilled off at 174- 178 'C, and after further distillation was dried with anhydrous calcium 'chloride. One hundred cc. of cymene was slowly added to an equal volume of concentrated sulfuric acid, Sp. Gr. 1.84, which had been heated to 100 *C. The cymene was easily sulfonate!, with a liberation of heat, it was necessary to keep the temperature constant at 1G0 # C, because of the ease with which a too vigorous reaction resulted, forming a highly condensed and insoluble black substance. Since the reaction is an exothermic one, no heating is necessary after it has been once started. The excess acid was neutralized with ten percent ilaOH, which was added at such a rate as to keep the temperature below 100° C. After neutralization the mixture of cymene sulfonic acid and sod- ium sulfate, was heated on the water bath for several hours until a reddish brcwg., clear solution was obtained. The reaction between cymene and sulfuric acid is:- . ' . ■ A ■ > - . ■ . ' 8 H GH CH* <0 1/ \ 3 + H 2 S 0 4 CH ^