Determination of Nordihydroguaiaretic Acid in Creosote Bush JOHN 0.PAGE A. and M.
College of Texas, College
Station, Tex.
A n analytical procedure was needed to determine the nordihj droguaiaretic acid present in creosote bush. In the procedure deb eloped, the machine-threshed, fresh creosote bush is extracted with n-but?l ether, which is then recovered by steam distillation. The impurities are separated bj- means of their substantial insolubility in boiling water or in boiling 0.259" acetic acid-0.1 qc sodium bisulfite solution and b 3 adsorption on activated carbon from a boiling aqueous 0.25% acetic acid-O.lq0 sodium bisulfite solution of the crude or impure nordihydroguaiaretic acid. The pure nordihydroguaiaretic acid is insoliible in the cool, carbonized, modified aqueous solvent and is filtered, washed, dried, and weighed. The nordihyclroguaiaretic acid content of two shipments of fresh machinethreshed creosote hush was found to be 1.84 and 1.3170.
T
HE determination of nordihydroguaiaretic acid in cmreosot e
bush has been difficult because colorimetric and optical methods are not specific for this acid. T h e work reported here is the quantitative separation of the impurities by chemical means and the consequent determination of nordihydroguaiaretic acid (SDG.4) by weighing t h e purified chemical as such. Lundlierg and Halvorson (9) devised procedures for the determination of nordihydroguaiaretic acid and other phenolic antioxidants in fats. Their data were based on the color reaction lietn-een an antioxidant phenol, including nordihJ-droguaiaretic acid, and a modified iron-bipyridine reagent, first described by Emmerie and Engel ( 2 ) . Although the reaction is not specific for nordihydroguaiaretic acid, it is useful in determining only one phenolic antioxidant, the identity of which is known. .In effort was made t o uSe ultraviolet spectrophotometry for the determination of nordihydroguaiaretic acid. Almost identical absorption spectra, with absorption maximum close to 2800 .I., were given by each of the following: twice recrystallized nordihydroguaiaretic acid, melting point 186-187" C. ; impure nordih?-droguaiaretic acid, melting point 181-185" C. : impure nordihydroguaiaretic acid, melting point 177-182" C., and red amorphous impurities, melting point 62-75" C. (adsorbed on au eluted from activated carbon). Structural similarity of nordihydroguaiaretic acid t o the impurities associated with and separated from the acid may account for this phenomenon. However, this explanation is not certain. I n the method given here, nordihydroguaiaretic acid i.5 separated from the impurities associated with it in the primary extract and in the crude nordihydroguaiaretic acid, and the pure acid is recovered quantitatively. A modest departure from the proximate assay method previously described (10) is the use of n-hutyl ether (boiling point 141-112O C.) rather than isopropyl ether as the solvent in contact with the threshed creosote bush and t o extract the nordihydroguaiaretic acid. T h e commercial, and other, extraction methods for nordihydroguaiaretic acid are disclosed in seven patents ( 1 , 5-8). T h e crude nordihydroguaiaretic acid, melting point 172180" C. (and similar melting ranges) is separated as described earlier ( 1 0 ) by boiling distilled-water extractions of the primary extract creosote or tar residue. The crude acid is purified b y recrystallization from boiling 0,25yGacetic acid-0.1 70sodium hisulfite solution. T h e impurities are removed from the impure nordihydroguniitietic acid polution b y adsorption on activated
carbon when the boiling solution, saturated with reqpect t o nordihgdroguaiaretic acid, is filtered through a prepared bed of the activated carbon. ivaller (12) used 10 to 1570 and 36yG acetic acid as solvents for the nordihydroguaiaretic acid. I n thir- laborat,ory, a number of the hj-droxy acids (lactic, citric, salicylic, tartaric, and phenol) were tried as recrystallization solvent for the nordihydroguaiaretic acid. However, acetic acid proved t o be better. Kumerous activated carbons x e r e investigated. T h e primary tar or creosote can be extracted directly, at, 100" C., with the recfystallization solvent (0.25% acetic acid-0.1 % sodium bisulfite solution), and then the resilting boiling crude nordihydroguaiaretic acid solution can be I~roughtin contact with activated carbon and filtered. The hot crude nordihydroguaiaretic acid solution can be stirred niechanicizlly with the activated carbon or the boiling crude nordi1iydroguai:iretic acid solution can he filtered through a carbon bed. Both pressureand vacuum-type filtration equipment were used in thip work. However, the direct purification is too cumliersome t o accomplish quantitative recovery in the laboratory. I n the direct method, the primary tar, freed of n-butyl ether, is extracted b y mechanically stirring with boiling 0.2570 acetic acid-0.1% sodium bisulfite solution rather than with boiling distilled water. T h e pure nordihydroguaiaretic acid, melting point 185-187" C., precipitates from the carbon-treated, filtered, cooled, 0.25% acetic acid-0.1 % sodium bisulfite extract of t h e primary tar. Distilled water extraction of the primary tar yields only t h e crude nordihydroguaiaretic acid, melting a t 172" t o 180" C. and similar melting points. T h e direct method of purification rva9 part of a proposal by the author for t h e production of nordihydrogriaiaretic acid. H o n ever, t h e procedure w a c-ritirized ~ liecaiiqe of the excessively large volumes of hot aqueous impure nordihydroguaiaretic acid solution which would be pumped through the filter press ( 1 1 ) . PROCEDURE
T h e sample, 1250 grams of frecih? green machine-threshed creosote bush, is extracted by tn-o successive 12-liter portions of cool peroxide-free (sodium bisulfite-washed) n-butyl et,her. T h e second solvent extraction gave assurance of complete recovery of the nordihydroguaiaretic acid. The sample is held in a fine-meshed, cylindrical copper basket, with twill cloth circles retaining the material a t the top and bottom. After the sample is extracted and drained free of solvent, the solvent is recovered from the extract solution b>- st,eam distillation. The recovery of n-butyl ether is almost complete. T h e broxn tar residue, or creosote, fluid a t 100" C. is extrarted quantitatively by 10 or 11 successive 3-liter portions of boiling distilled water. The boiling extracts are filtered through cotton. Crude nordihydroguaiaretic acid fraction$, melting a t 172180" C. and similar melting points, precipitate from the cool extracts. I n order to make certain that the nordihydroguaiaretic acid has been recovered quantitative1)-, excess extractions are made from n-hich no crude nordihvdroguaiaretic acid precipitates. T h e crude acid is filtered and dried a t 105: C. The colloidal >-ellow filtrate contains nordlh!.droguaiarttic acid and impurities. The filtrate liquor is extracted quantitatively XT-ith successive 1-liter portions of peroxide-free n-butyl ether. Usually two, sometimes three, n-butyl ether extractions are required to take the phenols and impurities completely out of a 15- or 16-liter portion of the filtrate liquor. The extracted filtrate liquor gives negative tests for phenols with 570 ferric chloride and also n-it,h concentrated sodium hydroxide solution. The crude nordihydroguaiaretic acid is obtained from the n-butyl ether solution in the same manner in which the crude nordihydroguaiaretic acid is recovered from the first n-butyl ether extract of the creosote hush. Purification of Crude Nordihydroguaiaretic Acid. The dry, 1266
V O L U M E 27, NO. 8, A U G U S T 1 9 5 5
1267
crude nordihydroguaiaretic acid, with the f (meltirig point 16T-179" C.), is purified from 16 to 18 liters of a boiling solution of 0. 0.lyo sodium bisulfite in distilled water. The crude nordihydroguaiaretic arid is dissolved by adding 0.5- to 1.0-gram increments slowly with stirring to the boiling aqueous solvent. Small amounts of tarry or resinous-looking impurities are insoluble. T h e boiling, intensely yellow solution is filtered bv vacuum through a hot bed of act,ivated carbon (Darco G60) i n a Biichner funnel. T h r impurities are adsorbed, and a fraction of the nordihydroguaiaretic acid is temporarily held by the artivated carbon. The pure nordihydroguaiaret,ic acid, melting point 185-187' C., c*ompletely precipitates from the cool carbonized filtrate, \vhirh is faintly colored. This acid is n-hite. The carbon is washed a t once while very hot viith successive I-liter portions of boiling distilled water until the xaqhed carbon is free of nordihydroguaiaretic acid-that is, until no nordihydroguaiaretic avid crystals form in the cooled carbon wash water. I.:xcess washings of the carbon w r e made to ensure t,he quantitative recovery of the nordihydroguaiaretic acid. Five or sis h i l i n g water estractions of the carbon and insoluble inipurities were usually needed. The nordihydroguainretic acid washed finin the carlion is caream colored. The boiling \vater rxtraction completel>- \i-arhes t h r nordih?-drcguniaretic acid from the carbon. Extraction of the n-aterwished carbon by isoprop!-l ether or n-butyl ether or hot concentrated acid solution nlrvnys failed to extract any nordihydroguxiaretic :wid from the $1-ater-Lvashedcarbon beds. The pure acid, melting point 185-187' C., is filtered, m-aPhed with distilled hvater, dried a t 105' C., and vieighed. T h e main yield of pure acid is collected and weighed separately. The carbon wash yield of nordihydroguaiaretic acid is treated siniilarly in order to separate the :-ield dat,a. The following are typical dat,a for the recrystallization of the crude nordihydroguaiaretic acid.
T a b l e 11. M i c r o d e t e r m i n a t i o n of C a r b o n a n d IIydrogen NDG.4 Sourcen Earlier shipment
Sample, 1Ig. Sordiliydroguaiaretic dcid 20.34
-Found. %
-
~~~~~
C
7 1 35 71 41)' Present sliiptnent 1 25.36 71.43 2 21.37 7 1 .3li 3 27.30 71 . 3 7 Unrecrystallized NordiIiydroguaiaretic Acid Tetrnocrtnte SDG.4 SaInple, Tetraacetate. G. G. Obtained Theory Parts/1000 Crude NDGA, twice recryst., n1.p. 186-1873 o t , .i2 0.9790 1 3237 1.5234 .. C. tit) 37r Earlier shipment 1.0234 1,5870 1,5925 -3 3 l i l i , 33 Present shipment lifi.88 1 0 . 9 8 8 9 1 5304 1.5388 -1 6 2 0 . 9 9 7 3 1.5474 1.5519 -2 9 00.14 -2.1 60.46 3 0.9914 1,5394 1.5427 a See Table I. 6 Theory for CisHrnOa. C Theory for CxHmOs.
H
7 83 7.33') 7.79 7 , It2 7.Ci2
D~i;$;:ll
6.j ti.43c
li
G , 11 6.7.5 6.72 tLfifi
under several headings: m t i n for the main yield arid C for t h e carbon wash yield. Rec. indicates the quantity of the nordihydroguniaretic acid ohtained from quantitative estraction of the combined recrystallization filtrates from the main and C yield< of nordihydroguaiaretic acid. Extraction of Recrystallization Filtrate. The conil)iiicd filtrate, after filtration of the nordihydroguaiaretic acid yield. rvas extracted by 1 liter of peroxide-free n-butyl ether. The first 0 . 2 3 7 , AceticCrude 0 . 1 % Bisulfite h-DG.A KDGA (1I.P. 185extraction was always complete and took out any nordihydroSolutions. (3l.P. 109187" C . ) fronia H?O-Insol. Inipwities Separated, Grams Liters 180° C , ) , Grams Crude. Grams guaiaretic acid and associated impurities. After the n-hutyl C Main ether had been steam-distilled, the small orange-red resithie. 8 22.5 6.1 2.6 1 9 (orange-red) liquid a t 100" C., \vas diPsolved in 1 liter of boiling 0.255; ac-etic Total 8 . 7 6 sodium hieulfite solution. This boiling solution \\-as acid-0.1 7 " 30-xrani carbon bed used. filtered through a 20-gram lied of G60 Darco with vawurii. T h e DISCUSSION O F RESULTS carbon bed then !vas washed tIvice, each time by 1 liter of l)oiling Crude iiordihydroguaiaretic acid is obtained 1)y hot distilleddistilled water. Any riordihydroguaiaretic acid whirh precipin.:iter estrwtion of the brown primarj- tar or ri'eosotr i.esidue tated from t h r cool carlionized filtrates was filtered, dried, a n d after distillation of the n-hut>-1 ether. T h e precipitated crude weighed. Purity of Nordihydroguaiaretic Acid. ~lic.rodeterniinations acid whicsh is filtered, dried, and weighed is termed A in Talilc I. The ciiicle acid, recovered quantitatively bj- means of witable of carbon and hydrogen ~ w r rmade on the nordihydroguaiaretic extraction of the filtrate liquor obtained froni the filtration of acid samples (Table 11) and on the unrecrystallized nordihydrocrude noi~dihyctroguniareticacid yield h, is claqsified uridrlr 13. guniaretic acid tetraac te derived from e:tch nordihydroguai:iwtic arid yield. The;? d:itn indicate it vwy high degree of purity for t h e ~. . -Iiordili~.droguaiareticarid samples. T a b l e I. l-ield of N o r d i h ~ - d r o g u a i a r e t i cAcid from Creosote BushR 111 the quantitative coiivewion of Crude h71GA _____ Recryst. NDGA, nordi1i~drogii:~iaretic acid to nordihydroMachine-Threshed .4 B Grams SDGA, giiaiaretic acid tetrancetnte, it ~ : i newss Creosote Bush Grams Rl.p., "C. Grams 3I.p.. "C. Main C Rec. Total 70 sai'y to acetylate the nordihydiogunia~rtic Earlier shipment 2G.l 172-79 24.2 167-78 17 9 5 . 0 0 1 23.0 1 84 :wit1 sample tvith e s c e s acetJ.1 chloride. Recent shipment 10.0 1.28 Knller (19) employed acetic :inhJ-tliide in 1 18.6 175-81 15.1 171-79 10.9 3.0 0 . 1 7 24.0 172-80 21.0 1G9-77 11 6 3 . 7 0 0 17.3 1.38 first describing the preparation of nordi28.16 134-78 14.7 1138-SO 10.7 4 . 9 0.2 13.8 1.26 3 12bO-qratn sample used. hydroguaiaretic acid tetra:tret:cte. Howb 0.037, S a C l added to increase precipitation of crude NDGA f r o m colluidal condition. ever, acetic anhydride did not rliiantitutively convert catechol or norrlihydroguaiaretic acid to the correqpoutling rliacactate and tetraacetate. The first estraction of the creosote bush sample by n-butyl The nordihydroguaiaretic acid tetraacetate was prepsrctl in ether was al\va)-a quantitative. This is demonstrated from the the folloning - wav. . fact that no nordihydroguaiaretic acid n'as ever obtained by The nordihydroguaiaretic acid sample was refluxed for 4 hour8 nleans of the s e c o r l ~n-l)utyl ether estraction of the creosote with 25 ml. of redistilled acetyl chloride in a giass esterification hush sample. The residual creosote or tar,. obtained from the apparatus, ~ l of~ the excess ~ acetyl ~ &loride t then ~ ~ . a y second n-butyl ether estraction, Tvas extracted three times Lvith boiled o f f on a hot Tvater bath. T h e cool reaction mixt,ure \vas dissolved in 75 ml. of diethyl ether. The ether solution was &liter portions of boiling distilled lvater. T h e nordihydroguaiaretic acid, melting point 185-18i~ c,, washed in a separatory funnel twice with 40-1111. portions of distilled water, twice with 50-ml. portions of 1% sodium bicarbonate was obtained by recrystallization of the mixed -4and B ions and twice with ~ O - ~ Iportions , of distilled of crude riordih).drogiiai3retic acid. The yield is ified The finnl \\-ater ll-ash !yap free of Ziny acidity or any t,icsrhoIi:ite ~~~
ANALYTICAL CHEMISTRY
1268 ion. The combined washings were re-extracted by two 25-ml portions of ether. The latter ether extract (50 ml.) was washed with 25 ml. of distilled water, then with 10 ml. of distilled water. T h e combined ether extract was filtered through a small cotton pad (in a buret funnel) into a tared beaker. The cotton was washed carefully with 10-ml. portions of ether after most of the ether had been evaporated from the extract in the beaker. The nordihydroguaiaretic acid tetraacetate was then dried a t 105" C. for a minimum of 2 hours, and held in a vacuum desiccator prior to microanalysis. The molecular weight of nordihydroguaiaretic acid, ClsH2?OI, is 302.36. The molecular weight of nordihydroguaiaretic acid tetraacetate, Cz,H3aOs, is 470 50. I n theory, 1.000 gram of pure nordihydroguaiaretic acid yields 1.5561 grams of noidihydroguaiaretic acid tetraacetate. ACKNOWLEDGMENT
The friendly cooperation of the Caqner Candelilla Co., Alpine and Presidio, Tex., which has supplied the fresh machinethreshed creosote bush for this work, is greatly appreciated.
LITERATURE CITED ( I ) ;Idanis, J. (to Regents of University of Minnesota), U. S. Patent 2,421,109 (May 27, 1947). (2) Eninierie, A., and Engel, R., Rec. trau. chim., 57, 1351 (1938). (3) Gisvold, 0. (to Regents of University of Minnesota), Brit. Patent 618,406 (Feb. 22, 1949). ( 4 ) Gisvold, 0. (to Regents of Gniversity of lIinnesota), U. S. Patent 2,382,475 (ilug. 14, 1945). (5) Ihid., 2,408,924 (Oct. 8, 1946). ( 6 ) Ihid., 2,421,117 (May27, 1947). (7) Ibid., 2,421,118 (May 27, 1947). (8) h ' d . , 2,444,346 (June 29, 1948). (9) Lundberg, 1%'. O., and Halvorson, H. O., Proc. I n s t . Food Technol., 6th Conj., 1945, 115. (10) Page, J. O., b s a ~CHEM., . 23, 296 (1951). (11) Stange, Wm. J., Co., Chicago, Ill., private communication. (12) Waller, C. W., and Gisvold, O., J . -4m. Pharm. Assoc., Sei.Ed., 34, 75 (1945). RECEIVEDfor review December 20, 1954. Accepted March 2 5 , 1955. Presented before the Division of Analytical Chemistry a t the 10th Southwest Regional Meeting of the AYERICAK CHEMICAL SOCIETY, Fort Worth, Tex., December 3, 1954.
Infrared Spectrophotomet ric Determination of AI Iethrin STANLEY K. FREEMAN Benzol Products Co., Newark, N. J. An infrared spectrophotometric method has been developed for the determination of allethrin. The intense 5.81-micron band w-as selected for this study, and it was ascertained that only one of the four impurities known to be present in the insecticide interfered at the analytical wave length. Chi ysanthemummonocarboxylic acid anhydride was shown to be present as a minor constituent in the samples investigated. The 5.56-micron band was utilized for determining the anhydride. Allethrolone has been determined by means of its 2.86-micron absorption maximum, and standard and differential techniques have been compared. cis- and Lransallethrins exhibit different absorptivities at 5.81 microns, and the relative amounts of the isomers were determined by their absorbances at 8.70 and 8.85 microns.
A
LLETHRIX is a commercially rtvailable insecticide similar to the pyrethrins in action.
CH,
HSC
CH3
c
/\
HBC
CHI
There are two methods a t present employed in industry for the analvsis of this substance, and both have certain disadvantages. The hydrogenolrsis procedure of Schechter ( 1 8 ) fails to take into account one of the interfering impurities present in commercial allethrin (chrysanthemummonocarboxylic anhydride)and, in some instances, gives erratic results when the purity of the insecticide is less than 90%. The ethylenediamine method ( 1 2 ) requires dailv standardization of solutions prior to their use, the
exact, location of the end point is difficult to detect when off-color samples of allethrin are analyzed, and the reagents employed are rather expensive. Cueto and Dale ( 3 ) have published a colorimetric method for determining allethrin, and Oiwa, Shinohara, Takeshita, and Ohno ( 1 6 ) investigated the polarographic analysis of ol-dl-lrans-allethrin. Harris (11) has developed a chromatographic method for the insecticide, and a spectrophotometric procedure has recently been reported (14). Khile t,his article was being reviewed, a paper (16)discussed the determination of allethrin by weighing the chromatographed 2,4-dinitrophenylhydrazone. Green and Schechter (8) have developed a similar method. Elliott (4)has recently published entomological data on the trails content of allethrin, and his average figure of 75% agrees well with that of the author. Elliott attempted to explain the reason for the radical difference between his results and t,hose of Gersdorf and IIitlin ( 7 ) by stating that it might be due to "different reactive conditions and varying nonstoichiometric rat,ios of the reagents in the preparations of the esters." Schechter stated that the materials supplied to Gersdorf for his studies were prepared by the procedure outlined in his original paper (17'). Therefore, some other reason must be sought to explain the divergency. Cromhie (4)recently found, by infrared spectrometry, that methyl chrysanthemumate contains 68% of the trans isomer. A short while later (10) Harper and Sleep observed t h a t chrysanthemumonitrile contains73% of this isomer. By means of a modified ;\O=\C method ( I ) , the quantity of trans-chrysanthemummonocarboxylic acid present in the racemic acid was found to be nearl!- identical n-ith that reported in this paper ( 1 9 ) . An infrared spectrophotometric method has been developed for determining allethrin, utilizing the intense 5.81-micron band (Figure 1). I t was first necessary to examine the infrared spectra of the inipuritie? occurring in commercial allethrin. Allethrolone (Figure 2), chrysanthemummonocarboxylic acid (Figure 3), its acid chloride (Figure 4),and its anhydride (Figure 5 ) \\-ere prepared, and i t was ascertained quantitatively, by determining the absorption of purified allethrin containing known amounts of added impuritks, t h a t only allcthrolone interfered a t 5.81 microns in the conceiitrations encountered in the technical product.
