NOTES
July 5, 1952
3411
TABLE I1 BIS-PHESOLSFROM FORMALDEHYDE KO.
20 21 22 23 24
25 26
Pro- PreRecrysced- ctpi- Time, Yield, tallizing Phenol ure tant" hr. N . p . , OC. % solvent 4,6-Di-l-butyl-irz-cresolA 3 1 1 4 215.3-216.3 0 2 . 0 Acetic acid 1 1 121.5-121.9 2 2 . 0 Heptane rr~-Phenyl-2,4-xylenol A 4-Chloro-o-cresolb B 4 '/a 199.2-196.4 8 3 . 7 Benzene 6-Chloro-o-cresol B 4 2 157.0-157.3 7 8 . 7 Benzene 4-l-Butyl-o-chloroB 4 3 123.2-123.7 5 1 . 5 Acetic acid phenol 6-l-Butyl-4-chloro-mA 4 18 181.6-182.5 7 2 . 2 Heptane cresol 4-Chloro-02-phenylB 4 1 1 4 191.7-192.1 72 . O Heptane isopseudocumenol
1, Heptane; 2, benzene; 3, glacial acetic acid; 4, water.
Analyses, % Empirical Carbon Hydrogen Chlorine formula Calcd. Found Calcd. Found Calcd. Found CaIHla02 8 2 . 2 6 8 2 . 3 8 10.69 1 0 . 6 5 7.02 6.91 C2gH?80? 8 5 . 2 6 84.96 4.75 4.49 23.86 23.80 CirH~C1202 6 0 . 6 1 6 0 . 9 1 4.75 5 . 0 2 23.86 23.86 60.67 C I S H I ~ C ~ O60.61 ? CiiHtaClaO? 66.12
66.17
6.87
6.85
18.62
18.85
C\?iH30C1202 67.47
67.54
7.39
7.45
17.32
17.25
CaiHaoClzOo
73.57
5,98
6.17
14.03 13.96
73.64
Shown in (7) as having m.p. 188".
TABLE 111 BIS-PHENOLSFROM BUTYRALDEHYDE 27 28 29 30 31 32 33
Thymol 4,fi-Di-l-butyl-rrt-cresol 4-l-Butyl-o-cresol 2-l-Butyl-pxesol 0-4-Phenyl-2,4-xyIenol 6-l-Amyl-m-cresol 6-?$-Butyl-?n-cresoI
A A A A A A A
1 3 3 1 1 1 1
3 14 14 18 5 14 2
163.1-165.8 9 8 . 5 113.5-124.1 26.0 180 8-131.5 89 I 126.4-127.2 88.5 108 8-109.2 7 6 . 5 163.8-163.6 1 3 . 0 121.4-122.0 5 3 . 5
Heptane Butanol Aceticacid Heptane Heptane Heptane Heptane
CxHarOz Ca&dh CtaH~sOz CoaH~oOz Cs~HarOz CzsHc?Or C?aHasO?
81.31 89.51 81.64 81.64 89.31 81.90 81.64
81.57 9.67 9.79 82.40 11.00 10.95 81.69 10.01 1 0 . 1 5 81.30 1 0 . 0 1 9.75 7.61 7.75 85.55 81.60 10.31 10.35 81.96 10.01 10.08
1, Heptane; 2, benzene; 3, glacial acetic acid; 4, water.
TABLE IV MISCELLANEOUS BIS-PHENOLS 34 35 4,6-Di-t-butyl-m- 2,4-Sylenol cresol Aldehyde Isobutyraldehyde 2,4-Dichlorobenzaldehyde A A Procedure Precipitant" 3 1 Time, hours 16 1 M.p., "C. 118.1-118.6 193.7-194.1 Yield, % 22.0 52.0 Recrystallizing solvent Butanol Heptane Empirical formula Ci4Hj402 CzsH&ls02b Carbon Calcd. 82.51 68.83 AnalyFound 82.33 titi. 66 Hydrogen % Calcd. 11.W 5.53 Found 11.31 5.79 1, Heptane; 2, benzene; 3 , glacialaceticacid; 4 , water. Chlorine, %; calcd. 17.67; found 17.65. KO.
Phenol
I
1
Procedure A . 4,4'-Pro'pylidenebis-( 6-t-butyl-m-cresol).Approximately 4 ml. of'concentrated HC1 was added to a well-stirred solution of 82.1 g. of 6-t-butyl-m-cresol (0.5 mole) and 14.5 g. of propionaldehyde (0.25 mole). The reaction was exothermic and the temperature rose from 30 to 75' within 5 minutes. The reaction mixture was further heated and held a t 95" for 4 hours, 100 ml. of heptane was added and the mixture cooled and held 1 hour a t 30". The crystalline product was filtered, washed with two 20-ml. portions of cold heptane and recrystallized from the same solvent a t boiling; yield 43.4% of fine white needles, m.p. 190.0-1 90.4 O. Procedure B. 2,2'-Methylenebis-(4-chloro-o-cresol),Concentrated HPSO~ was added dropwise to a well-stirred solution of 71.3 g. of 4-chloro-o-cresol (0.5 mole) and 7.5 g. of trioxymethylene (0.25 mole) in 50 ml. of glacial acetic acid. The temperature rose rapidly to 95" and the mixture solidified after 8 ml. of acid had been added. After standing 15 minut:s, 200 ml. of wa!er was added and the mixture cooled t o 30 The solids were filtered and washed with cold water until free of acidity. The crude product was taken up in 200 ml. of benzene and following decolorization with 10 g. of Darco G-60 gave fine white plates; m.p. 195.2196.4', yield 83.7T0.
Acknowledgment.-The authors are indebted to hlrs. Marcella Stubits for the analytical data. RESEARCH LABORATORIES MONSANTO CHEMICAL Co. ST. LOUIS4,MISSOURI
[CONTRIBUTION FROM
SOUTHERN REGIOSAL RESEARCH LABORATORY l]
THE
Alcoholysis of Cellulose with 2-Methoxyethan01~~~ BY MARYGRACEBLAIR
Methanolysis of cellulose or its derivatives has been used a very few times as a tool in structural studies of c e l l ~ l o s e . ~Partial ~~ methanolysis, or alcoholysis with other alcohols as well, has been suggested to replace hydrolysis or oxidation for the shortening of cellulose chains without the introduction of reducing end-groups in the production of industrial materials.6 Some data were given concerning the extent of reactions by the normal alcohols with from one t o five carbon atoms. The present study is concerned with the extent of cleavage which can be obtained with a new alcohol-2methoxyethanol-which does not appear to have been used previously for the alcoholysis of any polysaccharide. I t s high reactivity makes this alcohol worth consideration as an alcoholytic reagent for polysaccharides, particularly since the use of an autoclave is not required in order for the optimal reaction temperature t o be reached. That cellulose acetate is converted by acidic 2(1) One of t h e laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture, New Orleans 19, La. Article not copyrighted, ( 2 ) Known also a s ethylene glycol monomethyl ether and as Methyl Cellosolve. (3) Report of a study made under the Research a n d Marketing Act of 1946. (4) J. C. Irvine and E. L. Hirst, J. Chcm. Soc., 141, 1585 (1922). 123, 518 (1923); E. Heuser and S. S. Aiyar, Z. angcw. Chcm., Nr27 (1924). ( 5 ) R. E. Reeves, I.. W. Mazzeno, Jr. and C. L. Hoffpauir, THIS JCJWRNAL, 72, 4773 (1090). ( 0 ) R. R. Reeves. T T . S. Patent 2,520,983. Sept. 5 . 19;10.
:14 12
s0 11;s
Vol. i 4
of the curves. However, the time of the occurrence of the maxima can be assumed to coincide with the time of near completion of alcoholysis under mild conditions, where the destruction of optically active substances is shown to besmall. The validity of thisassumption isconfirmed by the correspondence between the rotation of alcoholyzed cellulose acetate and of 2-methoxyethyl p-glucopyranoside a t this time. Hence, from the positions of the maxima in Figs. 2 and 3, the rate of alcoholysis can be shown to be proportional to the concentration of the acid in the range 0.13 to 0.50 X. Furthermore, the rate is increased about 1.i-fold per 10" increase in teinI (j :i2 48 (2 perature in the range 90 to 110". \-et, there is 110 Time (hours). clearly defined optimal value for either concentraFig. 1. -Glucose derivatives in acidic 3-tiiethosycthar~oI tion of catalyst or temperature since conditions ( 3 g. of glucosc or equivalent per 100 inl. of alcohol, 0.13 .Y conducive to morc rapid alcoholysis are :iccoinp-tolucncsulfonic acid, 100"): 0, starch; 9, cu-D-glucosc; panied by a more r'ipid rate of decrease of optical e, cellulosc acetate: 6,2-niethoxycthyl 8-D-glucosidc. actixrity, presumably indicative of the destructioii of glucosides. iiiethoxyethanol to glucosides in high yield is denionstrated by the data in Fig. 1, in which observed rotations are plotted against time of treatment of cellulose acetate, cy-D-glucose, starch ant1 2-methoxyethyl p-D-glucopyranoside. The agreement of all rotations after the initial reaction period is indicative of comparable states for all-an indicstion which must mean conversion of each to a niixture of the atiomeric glycopyranosides with very little destructive action. The cy-isomer, the presence of which is indicated by the shift to the moderately high positive rotation, has not yet been obtained in crystalline form. No doubt, the extent of the mild destruction of optically active substances which does occur is measured by the slope 1 . 1 I I l l of the straight line common to the four curves after S 31 32 4s they converge (at 9 hours). The liiic continues Time (hours). with this slope for at least five days. For the sake 1;ig. 5.--Influcncc of concentration of acid on the alcoholyof convenience, the point for the fivc-day period has been omitted from the figure (also from Figs. sis of cellulosc acetate ( 2 . 5 g. of low viscosity acetate, variable amounts of p-tolucnc2-4). The more rapid rate of decrease in optical 25 inl. of ~-mctlioxycthai~ol, activity preceding the linear portion of the curve sulfonic acid, 100'): 6 ,0.15 N; 0, 0.25 .V; 0 , 0.50 is evidently caused by some shift during the isoin- i ,1.0 erization reaction. I t is slightly reflected i n the I " I l l / / curves for the alcoholysis of cellulose. acetate under the milder conditions. p-Toluenesulfonic acid was choseti for the catalyzing acid in these reactions with 2-inethoxy54 ethanol. Hydrogen chloride, the alcoholysis cat3 alyst used by Irvine and Hirst' in their methan2 olysis of acetylated or methylated cotton, reacts 3 rapidly with alcohols, and an effective concentration 5 2 car1 be maintained only a short while a t high tern3 peratures. The concentration of hydrogen chlo.= ride in Zniethoxyethanol dropped from 0.1,: to 0.03 :V in two hours a t 100". The use of a sulli(1 cieiitly high concentration of this acid (0.2.5 .Ir or higher) for complete alcoholysis of cellulosc io l'i acetate in a one-step treatment resulted in scverc T i t i i c (hours j. discoloration. However, with /~-toluciiesulfot~ic iicicl the acidity is iiiaintained, at~tltl-icrc is little I I& :j. Iiifluciicc of tcinpcr,iture 011 the a l r o l i o l y ~ io~f ititerference from colorrd products iiiitler ii riilige crllulo~cacetate (2.5 g. of low vlsco51ty acctlite, 25 1111 of 2 o f conditions suitable for coinplete alcoliolysis of the incthoxyethanol, 0.15 iV p-toluc~~csulfo~~ic acid) 0, 00" , acetate. u. 1000; e, 1 1 0 ~ ;e, 1200. Initial changes i n optical activity result ironi The usable range of temperature and concentraboth deacetylation and chain cleavage making uncertain determinations of rate from the slopes tion is limited on the lower side by regeneration of
M
I
A'V;
d
i
-
July 5, 1952
NOTES
3413
the cellulose, for enough chain cleavage should less effective than the latter for the cleavage of occur concurrently with deacetylation to avoid fibrous materials. precipitation of the deacetylated or partly deacetyIn contrast to the members of the glycol family, lated cellulose acetate. T h a t slight regeneration the monofunctional alcohols with boiling points occurs a t 90" with 0.15 N acid is shown by the near 100" or above, as exemplified by n-propanol development of a persistent turbidity. With and n-butanol, are poor reagents for the alcoholysis 0.15 N acid a t loo", the solubility properties change of cellulose acetate. They tend to regenerate the from those of the acetate to those of the poly- cellulose, which then becomes insoluble. However, saccharide in one to two hours but without precipi- butanol can be used satisfactorily with low vistation from solution. Hence, the best conditions cosity cellulose acetate if the temperature is kept for total alcoholysis approximate the 100" tempera- for two hours a t 120' (a temperature too destructure and 2.5% concentration (near 0.15 N ) of acid tive for long use) and is then lowered to looo, other selected by Combs, McCloskey, Sundberg and conditions being comparable to those of Fig. 4. Coleman as optimal for the alcoholysis of methylAlthough the major emphasis in the study of the ated disaccharides with p-toluenesulfonic acid reactivity of 2-methoxyethanol has been centered in benzyl alcohoL7 on the alcoholysis of a low viscosity acetate, the 2-Methoxyethanol is only slightly more reactive applicability of the reagent to other cellulosic toward cellulose acetate than is its ethyl analog. materials has been explored. Two other acetates These monoethers are compared in reactivity with one of which was initially insoluble, were alethylene glycol, propylene glycol and benzyl coholyzed without difficulty; hence, complete alcohol in Fig. 4. The reactivity of each alcohol alcoholysis of all cellulose acetates may be possible for the cleavage of cellulose acetate is a function of under the conditions suggested. its power as a so!vent as well as of its ability to Trimethylcellulose (Fig. 5) is characterized by cleave the bonds between anhydroglucose residues. great insolubility in 2-methoxyethanol in addition The experiments were performed with a low vis- to its possession of the difficultly hydrolyzable pcosity acetate in order to favor solubility, but only link. Hence, i t is alcoholyzed only slowly in conwith benzyl alcohol and with 2-methoxyethanol trast to cellulose acetate with its appreciable soluwere the reactions homogeneous throughout. Solu- bility and in contrast to starch, which although tion of the acetate in 2-ethoxyethanol required insoluble, has the more easily cleaved a-link. A about one hour, and in each of the glycols about commercial sample of degraded partially methylfive hours, from the addition of the acid. The ated cellulose eventually dissolved completely, but conclusion may be drawn that although the ethyl the procedure with 0.15 N acid required two days ether is slightly less reactive than the methyl ether, compared with less than half a day for the acetates. the latter retains a distinct advantage largely because it is a superior solvent. Ethylene and propylene glycol are less reactive than the monoethers toward glucose-glucose bonds and are much c inferior in solvent power. Benzyl alcohol is in0 .w dicated here to be more reactive than 2-methoxyv ethanol, but in the single example studied it was e 4
M
6
22
,
oi
I
20
L
1(i 32 48 Tiiiic (hours). Fig. 4i.-Alcoholysis of cellulose acetate (2.5 g. of low viscosity acetate, 25 i d . of alcohol, 0.15 N p-toluencsulfoiiic acid, 100'): 0, ethylene glycol; 6,propylene glycol; 3, benzyl alcohol; 0 , 2-ethoxyethanol; 0 , 2-mcthoxyethanol. (7) E . E. Combs, C. M . McCloskey, R . L. S u n d b e r g a n d G. H . Coleman. THISJOURNAI., 71, 276 (1949).
1
I
I
I
60
100 140 180 Time (hours). Fig. 5.-Alcoholysis of methylated polysaccharides ( 5 g. of triniethylglucose or equivalcnt per 100 ml. of P-methoxycthniiol, 0.15 N p-toluenesulfonic acid, I O O O ) : 8 , triniethylccllulose; 0, trimethyl-D-glucose; 0 , trimcthylstarch; X I triniethylccllulose (scparatc expcriiiieiit).
Results with several other cellulosic matcriakcotton, hydrocellulose, mercerized cutton, decrystallized cotton and tritriethylcellulose-are summarized in Table I. The measurement of optical activity and the iiieasurenient of weight loss are equally effective for the estimation of extent of degradation under mild alcoholytic conditions. Experimental Observed optical rotations were for the D-line of the bodium vapor lamp on solutions in 1-dm. tubes. Alcoholysis temperatures were controlled t o i1'. p-Toluenesullonic
News
341-1.
'I'AHLE I ALCOHOLYSIS OF COT,ION CELLULOSE A N D UERIVATIVIIS" 1-g. sample in 20 ml. of p-toluenesulfonic acid in 2-methoxyethanol; temperature, 100' unless otherwise indicated Cata-
Substance alcoholyzed
lysl,
lv
Time, hr.
Obsd. rot. 1 , dm. ~
Wt. loss calcd., S From From obsd. resir0t.h duer
Cotto11 015 2x +0.22 5 . 3 5.:1 Cotton 0 I5 IX .:j(i 8.9 8 , ; ) Cotton 1 iJ 24 .82 20.0 21 .o Cotton a t 120" 1. o 21 ~. . . 81 .o" Hydrocellulose 0 .I5 21 1
