Monolayers of Branched-Chain Fatty Acids I*

Transcription

1 182 Masami IZAWA [Vol. 25, No. 3 Monolayers Branched-Cha Acids I* By Masami IZAWA (Received February 18, 1952) Branched-cha fatty s have received much attention biological pots view. Some m are found normal cell several kds bacteria, while some m are strongly bactericidal. bactericidal activity a number branched-cha fatty s has been studied extensively Adams * Part this work presented at Meetg Chemical Society Japan, held at Tokyo, Sept, (1) W. M. Stanley R. Adams, J. Am. Chem. Soc., 54, 1548 (1932). his coworkers,(1) it has been stated that re is parallelism between bactericidal activity activity se s. However, exact mechanism bactericidal activity is still obscure. A number new branched-cha fatty s have been synsized at Chemical Department, Institute Infectious Diseases, Tokyo University, ir biological chemical proties have been thoroughly vestigated.(2) (2) M. Asano, U. Kameta, T. Komai I. Isho, Igakusoran (Japan), 1, 41 (1946); M. Asano, U. Kameta T. Wada, J. Pharmaceut. Soc. Japan., 64, 25 (1944); M. Asano T. Yamakawa, J. Pharmaceut. Soc. Japan, 70, 474 (1950); M. Assno, J. Ota U. Arlyoshi, Igakusoran (Japan), 1, 42 (1945).

2 June, 1952] A detailed Monolayers study Branched-Cha behavior se compounds may throw light on mechanism ir action. In fact, it has been reported that re is a relation between biological succic molecules activity alkyl substituted half esters orientation at air-water terface.(3) Un- Acids. I 183 Wher this is due stability or true hysteresis is uncerta. Each pot on mean at least three dependent measurements accurate 3 cent. Materials tunately, at present stage our knowledge, it is not possible correlate directly proties se s branched-cha fatty s used this eximent were obtaed Chemical biological activity. But, if we consider behavior ger or proties se s, clearer understg may be expected. Department, Institute Infectious Diseases, Tokyo University, courtesy late Pr. Asano. Palmitic purchased Dr. odor Schuchardt G. M. B. H. Chemische In this report, measurements cearea relations were made results were correlated structure configuration Fabrik, molecules Its meltg. recrystallized pot Results 1. Techniques Trialkylacetic ce-area methanol. 62. Discussions Acids.-Fig. two 1 shows trialkylacetic apparatus measurg ce-area Langmuir-Adam type balance. It consisted a nickel-plated brass trough cop float platum ribbons. To avoid contamation, whole trough, float system glass barriers were heavily coated solid paraff usual manner, y were rsed about one hour bee use. benzene a micropipette. area distilled sitivity calibrated palmitic volume water be degree, measured micro- agast cross on or ic water substrates. rsion balance cm. could tap sample dissolved redistilled spread on water means pipette sectional accuracy sendyne pressure ±0.05 dyne/cm. Sce se compounds med more stable films on substrates than on neutral or alkale solutions, sce it necessary mimize fluence heavy metal ions, eximents were made on 0.01N hydrochloric solution. Measurement started at about one mute after spreadg material at zero pressure, time terval between adjacent pots on ce-area about thirty seconds. If pressure changed rapidly time owg hysteresis, it read when no appreciable change observed on value one mute. Generally, cocidence between obtaed compression -expansion relatively poor. Fig. 1.-Force-area methylundecyldodecylacetic (I) ethyldecyldodecylacetic (II). Curve phthioic (III) after Stenhagen is also shown s figure. 20. cule, long films area are HCl, hydrocarbon are 20. chas at liquid-exped, is compressible A mole- A.2 film methylundecyldodecylacetic (I) collapses at about 7 dynes cm., whereas ethyldecyldodecylacetic (II) sts (3) J. H. Schulman W. McD. Armstrong, "Surface Chemistry", Intersoience Publishers Inc., (1949), p two se limitg 0.01 N higher reason this fact that while pressures difference I is solid, dynes. may be due II is liquid

3 184 Masami IZAWA [Vol. bulk state at room temature. Below 60A.2, II shows a flat portion dicates existence equilibrium between 3. Havg drops on (V)β-methyl-β'-ethylpentadecanoic In 20 Fig. three-dimensional substrate. 1. (III), reported phthioic liquid Stenhagen,(4)is at 25, No. 3 β,β',β"-trisikylpropionic Only One Long Cha.-Fig.3 Acids shows β-methyl-β'-ethyltridecanoic (VI). Both films are liquid-exped compressible about 35A.2 also shown. Phthioic is one normal constituents tubercle bacillus mula C26H52O2,isolated Anderson, (5) its molecular structure has been assumed be a trialkylacetic, especially ethyldecyldodecylacetic (II), Stenhagen(4) Robson.(6) Later, Polgar Robson(7) vestigated structure extensively concluded that it 3, 13, 19triethyltricosanoic. But exact constitution still remas be solved. It may be concluded at least our results that Phthioic is not identical I or II. 2.β-Methplpalmitic Acid.-β-Methyl- palmitic (IV) ms liquid-exped film, whose limitg area is 63 A.2, compressible about 30 A.2 as shown Fig. Fig.3.-Force-area ethyltridecanoic. ethylpentadecanoic 0.01N HCl, β-methyl-β'- β-methyl-β'- (VI) Diheptylacetic propionic (V) Acid,β,β'-Diheptpl- Acid γ, γ'-diheptylbutyric Acid.- effect position diheptylmethyl group [(C7H15)2-CH-] respect carboxyl group s examed (VII, VIII IX). As shown Fig. 4, limitg areas become smaller cearea stee as position substitution is separated carboxyl group. se s collapse at about 50 A.2 Fig.2.-Force-area mitic. β-methylpal NHCl,25. (4) E. Stenhagen S. 8tallberg, J. Biol. Chem., 139, 345 (1941). (5) R. J. Anderson, J. Biol. Chem., 97, 639 (1932). (6) R. Robson, J. Chem. Soc. (London), 505 (1940). (7) N. Polgar R. Robson, J. Chem. Soc., (London), 389 (1945). α-ethyl α-ethylpalmitic(x), α-ethylarachidic lic, (Fig.5).α-Ethylnonylic Acids.-α-Ethylnonyα-ethyletearic(XI) s(xii)were examed does not m a stable, probably because high solubility compound. X is liquid-exped, whereas s

4 June, 1952] Monolayers Branched-Cha Acids. I 185 XI XII show a transition liquidexped condensed states. latter two substances show a marked temature effect as shown Fig. 6. Fig. 6.-Temature 0.01 N effect Fie. 4.-Force-area diheptylacetic (VII),β,β'-diheptylpropionic (VIII) γ, γ'-diheptylbutyric 0.01 N (IX). HCl,12. effect on 7 (XIII longer, equilibrium Fig. (X),α-ethylstearic ethylarachidic N HCl.20. α-ethylpalmitic (XI), (XII). XIV α ce-area α-propylmyriatic α-substituted 7.-Force-area cids. myristic α-propyl- α-methyl-(xv)myrietic dicate tadecylic A groups ce-area is shown Fig. XV). As side cha becomes limitg area is larger pressure is lower. (XIII) Fig.5.-Force-area. HCl. 6.α-Methyl- - on α-ethylstearic 0.01NHCl,20 18 (XIV). after s. α-methylpen- Stenhagen. (XIV. XV)

5 186 Masami α-ethylpalmitic hagen(8) (XIV)reported falls between a dotted le s liquid-exped se Sten- as dicated figure. reported above type. In 1933, are all Langmuir proposed state.(9) exped two layers, a ory liquid-exped Accordg his ory, liquidfilms are composed essentially up beg an soluble oil layer consistg molecules, hydrocarbon portion lower a layer hydrophilic groups molecules exists at terface oil water phases acts as a gaseous film. ce-area relation this state g equation: where F: α:area k: T: can be represented follow- pressure, Boltzmann absolute molecule, constant, temature, F0: a constant relatg coefficient an assumed sistg hydrocarbon molecules film. spreadg oil layer conportion a0: a constant relatg actual cross-sectional area one molecule on. ce-area relations branchedcha fatty s examed fit this equation well. This ory has been opposed several authors,(10) but essentially it will be right, as poted out Adam,(11) irrespective mute difficulties. Sce two constants, F0 a0, equation may be considered as relatg structure molecules, it may be reasonable se constants as well as limitg area or area at collapse be characteristic molecular structure. values F0 a0 calculated eximental are listed Table 1. From table, it can be seen clearly that re are close relations between structure molecules values F0 a0. se relations are summarized as follows: i) When two long hydrocarbon chas exist molecule, constant a0 becomes about 40A.2 This is shown series 1 (except phthioic ) 4. Especially series 4, a0 value three s is determed diheptylmethyl radical [(C7H15)2-CH-] (8) E. Stenhagen, Trans. Faraday Soc., 36, 597 (1946). (9) I. Langmuir, J. Chem. Phys., 1, 756 (1933). (10) For example. W. D. Harks E. Boyd, J. Phys. Chem.. 45, 20 (1941). (11) N. f. Adam, " Physics Chemistry Surfaces". Oxd University Press, (1938). p. 67. IZAWA [Vol. 25, No. 3 is about 40 A.2, is twice value cross-sectional area one hydrocarbon cha, spite quite different shapes ce-area. Shereshefsky Wall(12) reported that dilauryl maleate ms a liquidexped film, a0 is 39.0A.2 Hence, two long hydrocarbon chas se compounds consist a hydrophobic portion molecules, st side side. It may be mentioned here that ao is practically equal "area at collapse", because ce-area are nearly vertical at collapse pot. ii) a0 films possese only one long cha molecule is about 20 A.2 Series 2, 3, 5 6 correspond this structure. But as shown series 6, longer side cha is, larger is a0,, presumably, smaller is -F0. value ac tuberculostearic [C8H17-CH(CH3)-(CH2)8COOH] is also about 20A.2 if calculated published data.(4) iii) An crease length long cha results crease -F0 value, but ac seems be dependent it. Calculations were made on two or s similar structure(α-ethyltridecanoic α-ethylpenta- decanoic s) based on reported Stenhagen,(4) y are cluded Table 1. From se figures, fluence cha length on F, value will be evident. It has been reported Langmuir(9) that, normal cha fatty s, re is a lear relation between number carbon ams s F0 as follows: where n is number carbon ams alkyl portion (CnH(2n+1)COOH). It can be concluded that re is a similar relation branched-cha fatty s examed here at least qualitatively. iv) As branchg shifts position α, through,β, carboxyl This v) group, is shown As becomes longer, -F0 dimishes. -F0 series side γ, creases respect this order. 4. cha α position a0 creases, apparently, Series 6 shows this regularity. se relations are a qualitative nature, hold as long as films are liquidexped type. Usg se relations, it should be expected that branched-cha fatty s or or compounds tracted natural favorable newly synsized or exproducts can be identified, cases, (12) J. L. Shereshefsky Soc., (1944) mation A. A. Wall, about J. Am. Clam.

6 June, 1952] Monolayers Branched-Cha Table Values F0 a0 Films F0 α0 were values exped structure m calculated F0 condensed may be Langmuir F-a uncerta Acids. I Equation Branched-Cha α0 are because Liquid-Exped Acids reported film Stenhagen et shows a al.(4) transition liquid- states. obtaed. Summary (1) Force-area relations s a number branched-cha fatty s have been vestigated. (2) se s are liquidexped type, on ic substrates, cearea fit Langmuir equation well. (3) Constants F0 a0 Langmuir equation have been calculated. It has been shown that re is a defite regularity between se constants structure molecules films. (4) It revealed that structure phthioic is not trialkylacetic type as postulated Stenhagen Robson. This work started at Department Chemistry, Faculty Science, Tokyo University under author appreciation direction Pr. wishes express Pr. Sameshima Sameshima. his scere his kd direction, also Dr. Akamatsu Dr. Tachibana Tokyo University, Dr. Umezawa National Institute Health ir greatly number advice present study. He is debted late Pr. Asano samples branched-cha s. National Institute Health, Tokyo also a fatty