Preparation of unsaturated aliphatic monobasic acids by metallation of α-olefins

PREPARATION OF UNSATURATED ALIPHATIC MONOBASIC ACIDS BY METALLATION OF a-OLEFINS * Yu. T. GORDASH, V. A . ZAKUPRA, V. A . SEROV, V. T. SKLYAR and V. S. DOBROV State Scientific Research and Design I n s t i t u t e for the Oil Processing and Petrochemical I n d u s t r y

(Received 20 January 1967)

As x result of the metallation of hydrocabons (direct substitution of hydrogen atom by metal) discovered by Shorygin [1], organo-metalie compounds of high reactivity are formed. Some of these, e.g. sodium derivatives of olefins initiate polymerization of butadiene [2-4], while others are starting compounds in the synthesis of surface-active substances, unsaturated aliphatic acids, in particular [5, 6]. Metallation is qualitatively studied in papers [7-9]. Having weak acid properties [10], olefins react with sodium alkyls with the substitution of hydrogen by sodium. RCH = CH~ ~- R 'Na->[RCH = CH] -Na Jr R 'H The anion, combined with Na, is apparently in equilibrium with isomeric forms. Salts of several acids are therefore formed during carboxylation. Salt of ~-vinylalkanoic acid

Salt of 3-alkenoic acid

R C H C H = CH2

R C H = CHCH~COONa

I

COONa

Salt of alkylacrylic acid

Salt of 2-alkcnoic acid

RCH2CCOONa

RCH2CH = CHCOONa

CH2

In addition to these salts of unsaturated acids, dibasic acid salts and a monobasic saturated acid salt are formed during the reaction, the latter from the initial sodiumalkyl. An attempt is made in this paper to evaluate quantitatively the yield of acids in metal substitution, which has not been the subject of previous studies [1-10]. EXPERIMENTAL

Experimental methods and analysis of acids. Metallation was carried out in a four-neck glass flask provided with a stirrer (10,000 rev/min), reflux condenser, capillary for passage of dry inert gas and a dropping funnel. So* Neftekhimiya 7, :No. 5, 764-773, 1967. 229

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Yu. T. GOI~DASHet al.

dium was added to an inert, aprotonic solvent (octane, dearomatized kerosine) in a flask at 110 °, while stirring vigorously. Without stopping agitation, the contents of the flask was cooled to -- 10 °, amyl chloride was then added through a dropping funnel. The molar ratio of sodium : amyl chloride was 1.2. Olefin was added in small batches to the sodium amyl formed. The mixture was gradually heated to 25-25 ° and retained at this temperature while stirring continously for two hours, then decanted onto excess solid carbon dioxide. To neutralize the sodium, ethyl alcohol and distilled water were added. The aqueous layer containing acid salts was extracted several times with petroleum ether, acidified to a pH of 3 with concentrated hydrochloric acid and the acid layer which had risen to the surface separated from water in a separating funnel. The aqueous layer was extracted with petroleum ether and after distillation the yields of acids (alkene and alkane) were determined. The aqueous layer remaining was saturated with sodium chloride and extracted with ether. Ether was then distilled off and the yield of dibasic acids determined. These acids were not studied as their yields ranged from 2 to 4%. Monobasic acids were analysed as methyl esters by gas-liquid chromatography using a Gazofrakt 300-V made by Virus K. G. (German Federal Republic). Esterification was carried by somewhat different methods from those described in a previous paper [11], with methanol in the presence of 5% HC1 (extraction of methyl esters of acids was carried out with isopentane, isopentane distillation being effected from a flask with a fractionating column at 40°). The reliability of the methods was evaluated with synthetic mixtures of caproic and Ca, Cv and Cs unsaturated acids. Rheoplex 4 was used as liquid phase, since its efficiency in separating saturated and unsaturated acids of natural origin has been extensively studied [12, 13]. Khromosorb P with a grain size of 0-2-0.3 mm, which had previously been maintained for several hours at a temperature Of red heat, was used as solid phase. The gravimetric ratio of liquid to solid phase was 20% by weight in all experiments; column length was 2-4 m, diameter 8 mm, carrier gas--helium, detection being by thermal conductivity. To analyse acids of different molecular weights under three isothermal operating conditions of the chromatograph (125, 165 and 200 ° ) the optimum rate of carrier gas was selected, which corresponds to the m a x i m u m number of theoretical plates, n. The n values given below, were calculated from the formula n = 5 . 5 4 ( t ~ / a o . 5 ) , where t R is the retention time and a0.~--the width of the peak at half-height for methyl esters of caproic acid (I) and 2 undecenoic acid (II). Temperature, °C Helium consumption, ml/min I II

125 83 2050 --

165 80 1660 3260

200 78 1440 2221

Preparation of unsaturated aliphatic monobasic acids 2

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FIG. 1. Chromatographic separation of methyl esters of unsaturated acids: /--Acids obtained from hept-l-ene. Separation temperature 125°, helium consumption 83 ml/min; / / - - A c i d s obtained from an industrial fraction of C9-Cii a-olefms. Separation temperature 165°, helium consumption 80 ml/min; I I I - - A c i d s obtained from a model mixture of C7, C10, C16 olefms. Separation temperature 200°, helium consumption 100 ml/min; I Methyl.esters of the following acids: 1 - - t r a n ~ - 2 - o e t e n o i c : 2 - - 3 - o e t e n o i e ; 3 - c i s - 2 - o c t e n o i e ; 4--oetanoic; 5--a-vinyl hexanoie; 6--hexanoic; 7--isopentane; II

8--2-dodecenoic; 9--3-dodeeenoic; 10--2-tmdecenoic; ll--3-undecenoic; 12--2-decenoic; 1 3 - - g-vinyldeeanoie; 14-- 3-deeenoic; 1 5 - - ~-vinylnonanoic; 1 6 - - 3-nonenoie; 17-- vinyloetanoic; 18-- 3-octenoie; 19-- ~-vinylheptanoie; 20-- ~-vinylhexanoie; 21-- hexanoie; 22--isopentane; III 23 -27--

2-heptadecenoic; 2 4 - - 3-heptadeeenoie; 2 5 - - ~-vinylpentadeeanoic; 2 6 - - 2-undecenoic; 3-undecenoie; 2 8 - - =-vinylnonanoie; 2 9 - - 2-octenoic; 3 0 - - 3-octen0ic; 3 1 - - hexanoie; 3 2 - - isopentane.

232

Yu. T. GORDASHet

al.

Results of chromatographic separation of methyl esters of acids of different molecular weights are given in Fig. 1 for three chromatographic temperature conditions. Chromatogram I consists of four main peaks, one of which corresponds to methyl ester of caproic acid. The logarithms of relative retention times of the three other peaks are satisfactorily situated on straight lines 4, 2, 1 (Fig. 2), corresponding to the homologous series of methyl esters of: a-vinylalkanoic, 3-alkenoic and 2-alkenoic acids. To evaluate the position of these straight lines, data are given in Fig. 2 for the homologeus series of methyl esters of saturated monobasic and diabasic acids (straight lines 3, 5). Identification of methyl esters of unsaturgted acids as methyl esters of 2-alkenoic and 3-alkenoic acids on straight lines 1 and 2, respectively for the Ce-C 8 series was confirmed b y the superposition of peaks of the individual components. In addition, as a result of oxidation with a sodium periodate and potassium permanganate mixture [14-16] at the double bond of methyl esters of 2-octenoic and 3-octenoic acids previously isolated b y preparative gas-liquid chromatography, corresponding saturated monobasic and dibasic

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Fie. 2. Dependence of relative retention times of methyl esters of acids on the

number of carbon atoms in the acid molecule. Methyl esters of: 1 -- 2-olefinoic acid; 2--3-olefinoie acid; 3--paraffinic acid; 4--a-vinylparaffinic acid; 5--dimethyl esters of saturated dibasic acids. Separation temperatures: numbers without a dash-125°; with one dash--165°; with two dashes--200 °. acids were obtained. Finally, the longer retention time on the chromatogram of 2-alkenoic acid, compared with 3-alkenoic acid, agrees with the relation earhier established [17] that in polyester phases retention time increases on shifting the double bond from the central position in the molecule in the direction of the carboxyl group.

Preparation of unsaturated aliphatic monobasic acids

233

We identified the peak of the methyl ester of a-vinylalkanoic acid from the absorption spectra in the infrared range of a given component isolated b y a preparative method. Figure 3 illustrates the spectra of liquid methyl esters of a-vinyl-hexanoic and 3-octenoic acids, obtained in an IKS-14 spectrometer. I t is well known that the vinyl group is characterized b y the frequencies of out-of plane deformation vibrations in the ----CH bonds at 990 cm -i [18] and in ----CH2 bonds at 910 cm -1. These bands are displaced in the direction of higher frequencies when the hydrogen atom at the a-carbon atom of the radical is substituted b y a functional group. This is typified b y the methyl ester of a-vinylhexanoic acid, where the intense band in the 930 cm -i region indicates the presence of an a-vinyl group in the molecule of the acid to be identified. The frequency of medium intensity near 1840 cm -1, which is typical of this t y p e of compound, should also be pointed out, this being the overtone of the band at 930 cm -~. There are reports in the literature on the predominant content of transisomers in olefins from alkali isomerization [19] and in unsaturated acids obtained b y metal substitution [7]. The investigations carried out b y the authors using specimens of ethyl mesters of 2-octenoic and 3-octenoic acids previously isolated also confirm this fact.

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FIG. 3. IR spectra of methyl esters of unsaturated acids (thicl~ess of the NaC1 vessel 15 microns): 1-- 3-octenoie acid; 2-- g-vinylhexanoie acid. The I B spectrum of the methyl ester of 3-octenoic acid illustrated in Fig. 3, in particular, has a band which is typical o5 the trans-position in the frequency range of out-of-plane deformation vibrations o f : C H (965 cm-1), whereas the band typical of the cis-position (690 cm -1) is absent. From data of gas-liquid chromatographic separation of isomeric methyl ester of 2-octenoic acid, cited in an earlier paper [20] it can be concluded that, under the conditions used b y the authors for chromatographic separation in a polyester phase, the methyl ester peak of 2-octenoic acid (Fig. 1) corresponds

234

Yu. T. GORDASK et al.

to the trans-isomer, whereas the peak of the cis-isomer is, apparently, observed immediately after the methyl ester of octanoic acid. As could be expected, we could not identify the alkylaryl acid, as the corresponding anion is unstable under the reaction conditions accepted [7]. Quantitative evaluation of acid composition. The dependence of the katharometer signal on the nature of the component mixture to be separated, the column use, amount of specimen fed and operating conditions selected impeded the used of this comparatively simple method of detection. Investigations carried out in past years enabled us to derive several relationships, which considerably simplify the quantitative evaluation of analytical results on methyl esters of saturated and unsaturated natural acids [21]. Determining the relation between retention times in various homologus series of acids and the calibrating coefficients, apparently, is one of the most successful methods of calculation 'proposed. However, the gradual "ageing" of the liquid phase and consequent decrease in the retention time of components make it essential also in this case to examine the calibration of the device. We examined the calibration of the device under the temperature and carrier-gas consumption conditions selected, using synthetic component mixtures, b y which the difference in detector readings (in peak area units per weight ~o) was taken into account on the one hand in relation to the methyl ester of caproic acid and on the other to the sum of methyl esters of unsaturated acids with the same numbers of carbon atoms. This method of calibration b y making it unnecessary to introduce a correction when calculating the gravimetric ratios between the unsaturated methyl esters indicated, was fully adequate for the comparative determination of relative amounts of components, in accordance with conditions of metallation. Calibration coefficients were therefore determined with pure methyl esters of caproic and unsaturated, 2-octenoic, 2-undecenoic and 2-heptadecenoic acids. In the first period of operation on liquid phase, calculated on methyl ester of caproic acid (for methyl esters of unsaturated acids the coefficients were accepted as unity) the coefficients had the following values. For a mixture of methyl esters of caproic and 2-octenoic acids (temperature of chromatographic separation 125°) _ 1.00. For a mixture of methyl esters of caproic and 2-heptadecenoic acids (temperature 165°)~0-92. For a mixture of methyl esters of caproic and 2-heptadecenoic acids (temperature 200°)--0.86. Calibration coefficients obtained for the above methyl esters were assumed to be the same under identical operating conditions of the device for methyl esters of acids with a variation range in the number of C6--C s, Cg--Cxa and C14--C17 carbon atoms, respectively.

Preparation of unsaturated aliphatic monobasic acids

235

W h e n a n a l y s i n g a n u n s a t u r a t e d acid m i x t u r e w i t h a w i d e r v a r i a t i o n in t h e n u m b e r o f c a r b o n a t o m s , t h e device w a s c a l i b r a t e d s e p a r a t e l y . Metallation of individual a-olefins. ~-Olefin s p e c i m e n s of 9 5 - 9 8 ~ p u r i t y w e r e s u b j e c t e d to m e t a l l a t i o n . M e t a l l a t i o n of several i n d i v i d u a l h y d r o c a r b o n s f r o m p e n t - l - e n e to h e x a d e c - l - e n e (Table 1) shows t h a t acids yield as ~o s t o i c h i o m e t r i c varies little w i t h a change of c a r b o n c h a i n length. A certain r e d u c t i o n in acid yield on increasing t h e m o l e c u l a r w e i g h t of initial a-olefins can be e x p l a i n e d b y a r e d u c t i o n of a c i d i t y of these h y d r o c a r b o n s w i t h t h e increase of t h e i r m o l e c u l a r weight. U s i n g t h e e x a m p l e of h e p t - 1 TABLE

1. R E S U L T S

OF METALLATION

OF OLEFIN HYDROCARBONS

Amount of amyl chloride taken 14.2g

"~ .~ ~ o~ Hydrocarbons and mixtures

Monobasic acids, % by wt.

~ ~

~ o~, "d .~

Composition of unsaturated acids % by wt. of the total

.~ ~'E

Pent-l-ene Hex 1-ene Hept-l-ene Dec-l-ene Tetradec- 1-ene I-Iexadec-1-ene

79.0 82.4 83.2 78.2 175.0 71.5

Hex- 1-ene/hept - l - e n e : l:l

67.3

Tetradec- 1-ene/hexadec- 1-ene (1:1)

84.0

Hex- 1-ene/hexadec- 1-ene (1:1) Hept - 1-ene/dec- 1-ene/hexadec- 1-ene (1:1:1)

72.7 86.0

80.0 81.6 82.5 79.1 72.2 70.4

20.0 18.4 17.5 20.9 27.8 29.6

14.8 12.6 11.0 9.5 8.9 8.45 9.2 9"0 83.0 17.0 11.7 9.8 7 0 " 5 29.5 1 8 " 0 4.0 80.9 1 9 . 1 20.7 7 7 " 0 33-0 11.8 7.8

42.6 43.0 43.4 49.3 56.7 58.0 27.5 29.0 28.3 24.3 43.4 16.9 16.7 14.0 12.3

21.4 21.2 21.8 23.6 27.0 29.3 12.4 15.5 15.7 16.5 10.7 5.7 11.1 9.4 9.4

33.4* 34.7~f 34.8 27.1 16.3 12.7 8.5 7.1 7.0 8.6 11.5 11.8 10.0 8.6 8.6

* As well as the acids indicated, the m i x t u r e contained 2.6% o t h e r acids. $ Some, 1 . 1 % o f o t h e r acids

ene it was p o i n t e d o u t t h a t u n s a t u r a t e d acid yield is m a r k e d l y influenced b y t h e increase of t h e CsH n C1/a-olefin m o l a r ratio.

Y u . T. GORDASH et al.

236

I f with te same molar ratio octenoic acid yield is 11.0 %, with a twofold excess of olefins--26.8°/o, with four-fold excess it is 47.0~/o. A further increase of olefin excess produces a less marked increase in unsaturated acid yield and it can therefore be concluded t h a t a four-fold excess is the most suitable. An increase in reaction time affects acid yield to a lesser extent, all experiments were therefore restricted to a reaction time of 2 hr. TABLE 2. EFFECT OF HEPT-1-ENE EXCESS AND METALLATION TIME ON THE YIELD AND COMPOSITION OF ACIDS, ~O BY WT. M e t a l l a t i o n t i m e i n all e x p e r i m e n t s w a s 2 h r . , i n t h e l a s t t w o - - 8 h r .

+--

.

~

O Product

~

composition, % by wt.

~ "9

Content of unsaturated acids, % by w t .

Composition o f olefins calculated as the total isolated, % by wt.

o o

0'0 0"5 2'0 4"0 6"0 0'0 4"0

83"2 84-0 84"7 85"5 90"8 80-5 84"7

82"5 81"5 53"3 27-3 15"6 60"6 11"6

17"5 18-5 46.7 72-7 84-4 40-0 88"4

11"0 11"6 26-8 47"0 56"4 24"3 56"8

42"8 44"8 47-8 49-3 53-7 59"5 62"4

23.8 22"1 27"6 38-1 34"9 31-3 30"3

33'4 33-1 24"6 12"6 11"4 9"2 6"3

14'4 15"3 17.8 11"5 9"6 18"5 33"3

37"2 36"1 36.2 36-6 41.1 27"5 1.1

48"4 48"6 45.9 51"9 49"3 54.0 55"6

* Calculated as the theoretical amount of olefln (from the equation of the reaction). t Calculated as amyl chloride.

Tables 1 and 2 give the quantitative distribution of various types of unsaturated acids. On increasing reaction time, the yield of 2-alkenoie acids decreases, which is in agreement with the data obtained in a former paper [7]. Reduced acid yield is also observed on increasing olefin excess, which can be explained by the ease of isomerization of the double bond. The fact of isomerization is confirmed by the composition of the olefins isolated (Table 2). A reduction in the acidity of a-olefins with higher molecular weight is satisfactorily confirmed by results of metallation of synthetic a-olefin mixtures (Table 1). Metallation of a hex-l-ene and hept-l-ene mixture with a 1 : 1 molar ratio produces equal quantities of heptenoic and oetenoic acids. In metallation of tetradec-l-ene mixed with hexadee-l-ene the

Preparation of unsaturated aliphatic monobasie acids

237

yield of corresponding acids also varies little, whereas during the metallation of hex-l-en6 mixed with hexadec-l-ene the proportion of low-molecular weight acids in the unsaturated acid mixture markedly increases. A similar pattern is observed during the metallation of an equimolar mixture of hept-l-ene, dec-l-ene and hexadec-l-ene. The marked variation in the yields of acids, corresponding to hex-l-ene and hexadec-l-ene, cannot only be explained by the varying acidities of initial a-olefins. This effect can, apparently, be also explained by the different efficiences of alkyl sodium and alkenyl sodium as catalysts of isomerization of the double bond. Morton [22] pointed out that alkenyl sodium is a more effective cat aiyst than alkyl sodium. It can thus be assumed that during the metallation of a mixture of olefins with different molecular weights, owing to the higher acidity of lowmolecular weight a-olefins, metallation takes place faster than with high-molecular weight olefins. The alkenyl sodium formed considerably accelerates isomerization of the high-molecular weight hydrocarbon double bond, which reduces even further the activity of this hydrocarbon and consequently, also the rate of metal substitution. As a result, the yield of low-molecular weight acids increases and that of high-molecular weight acids, sharply falls. The accuracy of this assumption is proved by the fact that low-molecular weight acid yield (calculated stoichiometrically) in this case is about twice as high as in the case of metallation of only one corresponding individual low-molecular weight olefin hydrocarbon (Table 1). As the high-molecular weight hydrocarbon hardly takes part in the reaction, there are two moles of amyl sodium per mole of low-molecular weight hydrocarbon. According to the law of mass action, this should increase the yield of low-molecular weight acids, which is observed in practice.

Metallation of narrow a-olefin fractions obtained by thermal cracking of para~ns. Experiments on metallation of individual a-olefins showed that the degree to which reagents, such as amyl and sodium chloride are involved in the reaction is observed in the case of considerable ~-olefin excess. Some authors studied the possibility of obtaining unsaturated acids from various ~-olefin fractions obtained from thermal cracking of paraffins [23]. To investigate the efficiency of using these fractions of unsaturated acids in the production of alkyd resins, oil additives, lubricating greases, considerable quantities of these acids were synthesized in an experimental laboratory metal reactor. The general appearance of the reactor is shown in Fig. 4. A modified design of the mixing device made it possible to achieve good dispersion of sodium with a stirrer speed of 2800 rev/min. A special feature of the stirring device is the upper blade, which directs the liquid flow downwards, the lower blade directs it upwards and the whole

238

Y u . T. GORDASH et al.

strong whirling dispersion of sodium is broken b y the blade system welded to the internal walls of the reactor. The yield and properties of unsaturated acid obtained in glass and metal reactors are similar. The properties of narrow unsaturated acid fractions obtained in a glass reactor were described in a previous paper [23].

IC 7

FIG. 4. Laboratory metal reactor: 1--Electric motor; 2--connecting sleeve;

3-- stirrer shaft; 4-- blade system; 5-- stirrer blades; 6 -- cooling jacket; 7-- electric heating. The use of gas-liquid chromatography made it possible to interpret the composition of monocarboxylic acids obtained b y metallation of narrow a-olefin fractions. An example of gas-liquid analysis of one of these fractions is given in Fig. 1 (middle curve). A fraction was analysed of acids obtained from a-olefins, boiling in the range of 147-193 ° and containing 85% unsaturated hydrocarbons 780//0 of which were a-olefins. Four groups of peaks were obtained which corresponds to acids Cs, C9, C10, Cn and C12, the content of these acids being 12.0; 6.0; 14.8; 39.0 and 28.2°//0, respectively. Consequently, the initial oiefin fraction basically consisted of C10 and Cn hydrocarbons. This fraction and the C1a--C14 acid fraction were tested as modifiers for alkyd resins. The tests show

Preparation of unsaturated aliphatic monobasic acids

239

O

t h a t t h e v a r n i s h films of a l k y d resins, modified b y u n s a t u r a t e d acid fractions, m e e t all r e q u i r e m e n t s for p a i n t a n d v a r n i s h coatings. I n addition, t h e use o f these u n s a t u r a t e d a l i p h a t i c acids as modifiers for a l k y d resins enables t h e v a r n i s h layers t o d r y u n d e r n a t u r a l conditions. T h u s , t h e acids o b t a i n e d b y m e t a U a t i o n o f ~-olefin f r a c t i o n s are c a p a b l e of r e p l a c i n g d r y i n g a n d s e m i - d r y i n g v e g e t a b l e oils in t h e p a i n t a n d v a r n i s h i n d u s t r y .

SUMMARY

1. A s t u d y w a s m a d e o f t h e effect o f r e a c t i o n conditions on t h e yield of u n s a t u r a t e d acids f o r m e d d u r i n g c a r b o x y l a t i o n of p r o d u c t s o b t a i n e d f r o m m e t a l l a t i o n o f ~-olefins w i t h a m y l s o d i u m . 2. T h e yield o f u n s a t u r a t e d acids d e p e n d s t o a slight e x t e n t on t h e molecular w e i g h t of initial ~-olefins a n d is d e t e r m i n e d b y t h e m o l a r r a t i o of r e a c t i n g c o m p o n e n t s . T h e larger t h e ~-olefin excess, t h e higher t h e yield of u n s a t u r a t e d acids. 3. D u r i n g m e t a l l a t i o n o f a m i x t u r e of~-olefins w i t h m a r k e d l y different molecular weights t h e low m o l e c u l a r w e i g h t h y d r o c a r b o n s m a i n l y r e a c t w i t h metals. 4. I t w a s s h o w n t h a t , in principle, it is possible to a n a l y s e q u a n t i t a t i v e l y m i x t u r e s of u n s a t u r a t e d acids o b t a i n e d d u r i n g m e t a l l a t i o n o f n a r r o w f r a c t i o n s o f i n d u s t r i a l ~-olefins. Translated by E. S~MER~. REFERENCES

1. P. P. SHORYGIN, Ber. dtseh, chem. Ges. 41, 2711, 27171, 2723, 1908 2. A. A. MORTON, E. E. MAGAT and R. L. LETSINGER, J. Amer. Chem. Soc. 69, 950, 1947 3. A. A. MORTON, Industr. and Engng Chem. 42, 1488, 1950 4. A. A. MORTON, F. H. BOLTON, F. W. COLLINS and E. F. CLUFF, Industr. and Engng. Chem. 44, 2876, 1952 5. French Pat. 1353392, 13. 01. 64; Chem. Abstrs. 61, 1760d 6. French Pat. 1352735, 6.01.64; Chem. Abstrs. 60, 15 738d 7. A. A. MORTON, F. D. MARSH, R. D. COOMBS, A. L. LYONS et al. J. Amer. Chem. Soc. 72, No. 8, 3785, 1950 8. R. A. BENKESER, D. J. FOSTER and D. W. SANVE, Chem. Rev. 57, 1~o. 5, 867, 1957 9. C. D. BROADDUS, T. J. LOGAN and T. J. FLAUTT, J. Organ. Chem. 28, No. 5, 1174, 1963 10. A. I. SHATENSHTEIN, Izotopnyi obmen i zameshchenie vodoroda v organicheskikh soyedineniyakh (Isotope Exchange and Substitution of Hydrogen in Organic Compounds). Izd-vo AN SSSR, Moscow, 1960 11. W. STOFFEL, F. CHU and E. H. AHRENS, Analyt. Chem. 31, 307, 1959 12. W. STUVE, Fette, Seifen, Anstrichmittel 63, No. 4, 325, 1961 13. A. JART, Fette, Seifen, Anstrichmittel 61, No. 7, 541, 1959 14. F. P. JONES and J. A. STOLP, Canad. J. Chem. 35, 71, 1958 15. E. RUDOLFF, J. Amer. Oil Chemists' Soc. 43, 1784, 1965 16. E. P. JONES and E. DAVIDSON, J. Amer. Oil Chemists Soc. 42, 121, 1965 17. A. T. JAMES, J. Chromatogr. 2, 552, 1959

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18. L. BE1LL~aMI, Infrakrasnye spektry molekul (Infrared Spectra of Molect~]es). Izd-vo inostr, lit., Moscow, 1957 19. G. PAINS and L. SIIAAN, Kataliz, polifunktsional'nye katalizatory i slozhnye reaktsii (Catalysis, Polyfunctional Catalysts and Complex Reactions). Moscow, Mir, 1965 20. O. MERCURI, N. E. CARROZONI and R. It. BRENNER, J. Amer. Oil Chemists Soc. 41, 89, 1964 21. A. G. VERESHCItAGIN, Usp khimii 33, 1349, 1964 22. A. A. MORTON, J. Organ. Chem. 20, 839, 1955 23. Yu. T. GORDASH, V. A. SEROV and V. T. SKLYAR, Khimiya i tekhnologiya topliv i masel, No. 5, 21, 1967