Full Text
CHEMISTRY
Yu. A. Oľdekoп, K. L. Moiseichuk, Academician of the Academy of Sciences of the BSSR
A. N. Sevchenko and I. P. Zyatkov
1,1′-BIS-ACYLPEROXY-DICYCLOHEXYL PEROXIDES
When hydrogen peroxide acts on cyclohexanone, the so-called “cyclohexanone peroxide” is obtained, an industrial product widely used as an initiator of polymerization and an initiator of other radical processes. This peroxide is a mixture of several peroxide compounds, the ratio of which varies depending on the synthesis conditions. According to Criegee’s data (¹), it consists of 1,1′-bis-hydroxy-dicyclohexyl peroxide (I), 1-hydroxy-1′-hydroperoxy-dicyclohexyl peroxide (II), and 1,1′-bis-hydroperoxy-dicyclohexyl peroxide (III). Additional data concerning the synthesis, structure, and properties of I, II, and III are available in works (²–⁴).
There is also information concerning the acylation of I, II, and III, almost all of it relating to the acylation of II. Thus, by the action of acid chlorides on II in the presence of pyridine, 1,1′-bis-acyl-cyclohexyl peroxides (¹,⁵) $C_6H_{10}(OOCOR)_2$ (IV) were obtained, where $R = CH_3,\ C_6H_5,\ o\text{-}ClC_6H_4,\ n\text{-}BrC_6H_4,\ m\text{-}NO_2C_6H_4,\ n\text{-}NO_2C_6H_4$.
As two of us have shown, IV (with $R = CH_3$) is obtained in higher yields by the action of acetic anhydride on II in the presence of anhydrous sodium acetate (⁶).
Regarding the acylation of I and III, it has only been noted that I, under the action of benzoyl chloride, gives small amounts of benzoyl peroxide, while III forms 1,1′-bis-benzoperoxy-dicyclohexyl peroxide (¹). Neither the yields nor the properties of the latter compound are reported.
It seemed of interest to us to investigate the reaction between III and acid chlorides and anhydrides in order to study the possibility of synthesizing a new class of peresters. We investigated the reaction of III with the acid chlorides of acetic, propionic, n-butyric, n-capric, and chloroacetic acids in the presence of pyridine, as well as the reaction with acetic anhydride in the presence of anhydrous sodium acetate. The reaction proceeds according to the following scheme:
\[ \begin{aligned} &\text{(dicyclohexyl hydroperoxide structure)} + 2RCOCl \longrightarrow \text{(1,1′-bis-acylperoxy-dicyclohexyl peroxide structure)} + 2HCl \end{aligned} \tag{V} \]
In this case the yields of 1,1′-bis-acylperoxy-dicyclohexyl peroxides (V), calculated on III, were (in percent) as follows: for 1,1′-bis-acetylperoxy-dicyclohexyl peroxide (Va), 78; 1,1′-bis-propionylperoxy-dicyclohexyl peroxide (Vb) 78; 1,1′-bis-butyrylperoxy-dicyclohexyl peroxide (Vc) 38; 1,1′-bis-caprinylperoxy-dicyclohexyl peroxide (Vg) 59; 1,1′-bis-chloroacetylperoxy-dicyclohexyl peroxide (Vd) 38. The yield of Va obtained by the action of acetic anhydride was 92% of theoretical.
All the peroxides are solid crystalline substances with comparatively low melting points. They are stable on storage. On very prolonged storage their activity decreased somewhat. Thus, the activ-
The activity of Vb decreased from 12.6 to 10.9 upon storage for half a year, and the activity of Vv—from 11.5 to 10.4 over four months. All the peroxide compounds obtained, except Vg, are sensitive to friction and impact; they explode with great force. They are readily soluble in benzene and carbon tetrachloride, and somewhat less soluble in alcohol.
For Va—Vd, as well as for III and IV (with R = CH₃),* infrared spectra were obtained in the transmission region of the NaCl prism of an IKS-14 infrared spectrophotometer. 0.1 M solutions of the peroxides in CCl₄ were studied with an absorbing-layer thickness of 0.25 mm (Figs. 1 and 2).
Fig. 1. Infrared transmission spectra of organic peroxides: I, Ia—1,1′-bisacetylperoxy-dicyclohexyl peroxide; II—1,1′-bispropionylperoxy-dicyclohexyl peroxide; III—1,1′-bisbutyrylperoxy-dicyclohexyl peroxide; IV—1,1′-biscaprinylperoxy-dicyclohexyl peroxide; V—1,1′-bischloroacetylperoxy-dicyclohexyl peroxide.
In Fig. 1 (curves I and Ia) are shown the infrared spectra of Va, obtained by two different methods. Their spectra are identical. They differ from the spectrum of IV (with R = CH₃), Fig. 2 (curve II), in that the latter lacks the band with a maximum at 930 cm⁻¹, and also by a significant difference in the intensities of a number of bands.
For all the peroxides the spectra have a similar structure and possess a whole series of characteristic bands. On the basis of the available experimental material and literature data, they may preliminarily be interpreted as follows.
A very intense band in the region 1765–1800 cm⁻¹ belongs to vibrations of the C=O group. Here only one absorption band of the carbonyl-group vibrations is observed, whereas in diacyl peroxides there are two bands in this spectral region, belonging to C=O vibrations.
In all spectra an intense band with a maximum at 1452–1455 cm⁻¹ is observed. It belongs to scissoring vibrations of the CH₂ groups of the ring. This interpretation agrees well with the literature data (⁷). The bands of deformation vibrations of CH₃ and CH₂ groups of open chains in the spectra of complex compounds containing both rings and open chains are very difficult to identify, since the absorption bands of the rings and of these groups overlap with one another. However, the band of the symmetric deformation vibration of the methyl group at 1350–1370 cm⁻¹ is very stable if the methyl group is attached to another carbon atom, and especially to the C=O group, whose influence on the stability of this band is very great. In the spectra of Va—Vg, Fig. 1 (curves I, II, III, and IV) and in the spectrum of IV (with
* The IR spectrum of IV is given in (⁵), but only the vibration frequencies of the C=O group were studied.
\(R = CH_3\), Fig. 2 (curve \(II\)) we observe this band, the interpretation of which raises no doubts. The antisymmetric deformation vibrations of the methyl group at 1450–1455 cm\(^{-1}\) do not appear in the spectra, since in this region they are overlapped by the scissoring vibrations of the CH\(_2\) groups of the rings, whose number is large in comparison with the CH\(_3\) groups.
Two intense bands with maxima at 1195–1200 and 995–1000 cm\(^{-1}\) are observed only in the spectrum of Va, Fig. 1 (curves \(I\) and \(Ia\)), and in the spectrum of IV (with \(R = CH_3\)), Fig. 2 (curve \(II\)). Hence it may be concluded that the frequencies mentioned should be assigned to vibrations of the group
\[
-\mathrm{C}-\mathrm{CH}_3
\]
\[
\left\| \atop \mathrm{O}\right.
\]
at the end of the chain.
Fig. 2. \(I\)—1,1′-bis-hydroperoxy-dicyclohexyl peroxide;
\(II\)—1,1-bis-acetyl-cyclohexyl peroxide.
The introduction of CH\(_2\) and CH\(_2\)Cl groups changes the vibration frequencies and leads only to broadening of adjacent bands.
A very intense band with a maximum at 1150–1160 cm\(^{-1}\) is present in the spectra of all the peroxides. In the literature \(^{(8)}\), for compounds containing the hydroperoxy group
\[ >\mathrm{COOH}, \]
this band has been interpreted as a stretching vibration of the
\[ >\mathrm{C}-\mathrm{O} \]
bond. The presence of any sufficiently characteristic vibration bands of the C—O bond in the above peroxides is unlikely. It is more natural to assume that the appearance of this band is associated with vibrations of the entire chain
\[ -\mathrm{C}-\mathrm{O}-\mathrm{O}-\mathrm{C}- \]
as a whole, and not only of the C—O bond.
The two bands with maxima in the regions 1097–1115 and 1065–1075 cm\(^{-1}\) should probably also be assigned to vibrations of this chain.
In the spectral region 830–900 cm\(^{-1}\) there are two weak absorption bands. For compounds containing the hydroperoxy group
\[ >\mathrm{COOH}, \]
the interpretation of bands in this region was given in work \(^{(9)}\), where the band at 840 cm\(^{-1}\) was assigned to the OOH chain, and the band at 880 cm\(^{-1}\) to O—O vibrations. For peroxides Va—Vd, as well as for IV (with \(R = CH_3\)), one can hardly expect the appearance in the infrared spectrum of stretching vibrations of O—O bonds.
Experimental Part
III was obtained according to \(^{(1)}\). Yield 38.5%. M.p. 82–83°. Molecular weight: found 248 (benzene), calculated 262.3.
\[ \begin{aligned} &\text{Found, \%: } &&\mathrm{C}\ 55.54;\ 55.40;\quad \mathrm{H}\ 8.41;\ 8.86^* \\ &\mathrm{C}_{12}\mathrm{H}_{22}\mathrm{O}_6.\ \text{Calculated, \%: } &&\mathrm{C}\ 54.94;\quad \mathrm{H}\ 8.45 \end{aligned} \]
Experimental Procedure
To a vigorously stirred solution (0.01–0.02 mole) of III in pyridine (0.05–0.1 mole), [[unclear: sentence continues on next page]]
\[ \begin{array}{l} \hline \end{array} \]
* Before combustion the micro-weighed sample was mixed with quartz sand. The authors express their gratitude to Z. M. Grabovskaya for carrying out the microanalyses.
acid chloride (0.03–0.06 mole) was added. The reaction temperature was maintained in the range −10–0°. After addition of the acid chloride, the reaction mixture was stirred for another 1–1.5 hr, then poured into cold water. The precipitate that formed was separated, washed 2–3 times with water, and recrystallized.
Va. 2.62 g (0.01 mole) of III was taken. 2.7 g of Va was obtained (from a mixture of alcohol with benzene). Yield 78.0%. M.p. 78–78.5°. Molecular weight: found 323.5 (benzene), calculated 346.4; active O: found 13.5; 13.9; calculated 13.8*.
Vb. 2.62 g (0.01 mole) of III was taken. 2.93 g of Vb was obtained (from alcohol with benzene). Yield 78.3%. M.p. 40–40.5°. Molecular weight: found 334.1 (benzene), calculated 374.4; active O: found 12.4; 12.9, calculated 12.8.
\[ \begin{aligned} &\text{Found: } \%\,\mathrm{C}\ 57.59;\ 57.40;\ \mathrm{H}\ 8.23;\ 8.31\\ &\mathrm{C}_{18}\mathrm{H}_{30}\mathrm{O}_{8}.\ \text{Calculated: } \%\,\mathrm{C}\ 57.74;\ \mathrm{H}\ 8.07 \end{aligned} \]
Vc. 3.6 g (0.0137 mole) of III was taken. 2.1 g of Vc was obtained (from warm alcohol with subsequent cooling with ice). Yield 38.1%. M.p. 52–52.5°. Molecular weight: found 374.7 (benzene); calculated 402.4; active O: found 11.2; 11.8; calculated 11.9.
\[ \begin{aligned} &\text{Found } \%:\ \mathrm{C}\ 60.08;\ 59.70\ \mathrm{H}\ 8.40;\ 8.19\\ &\mathrm{C}_{20}\mathrm{H}_{34}\mathrm{O}_{8}.\ \text{Calculated } \%:\ \mathrm{C}\ 59.69;\ \mathrm{H}\ 8.51 \end{aligned} \]
Vg. 2.62 g (0.01 mole) of III was taken. 3.38 g of Vg was obtained (from alcohol with benzene). Yield 59.2%. M.p. 45–46°. Molecular weight: found 515.5 (benzene), calculated 570.7; active O: found 8.3; 8.2; calculated 8.4.
\[ \begin{aligned} &\text{Found } \%:\ \mathrm{C}\ 67.18;\ 67.44;\ \mathrm{H}\ 10.5;\ 10.2\\ &\mathrm{C}_{32}\mathrm{H}_{58}\mathrm{O}_{8}.\ \text{Calculated } \%:\ \mathrm{C}\ 67.35;\ \mathrm{H}\ 10.24 \end{aligned} \]
Vd. 5.2 g (0.02 mole) of III was taken. 3.2 g of Vd was obtained (from alcohol with benzene). Yield 38.5%. M.p. 76.5° (decomposition). Molecular weight: found 383 (benzene); calculated 415.3; active O: found 11.1; calculated 11.5.
\[ \begin{aligned} &\text{Found } \%:\ \mathrm{C}\ 45.55;\ 45.70;\ \mathrm{H}\ 6.46;\ 6.44;\ \mathrm{Cl}\ 17.04;\ 16.71\\ &\mathrm{C}_{16}\mathrm{H}_{24}\mathrm{O}_{8}\mathrm{Cl}_{2}.\ \text{Calculated } \%:\ \mathrm{C}\ 46.27;\ \mathrm{H}\ 5.82;\ \mathrm{Cl}\ 17.07 \end{aligned} \]
Va. With acetic anhydride. To a mixture of 5 ml of acetic anhydride and 0.1 g of anhydrous sodium acetate, with vigorous stirring, 1 g of III was added. The reaction temperature, 31–32°, was maintained for 2 hr, after which 40 ml of cold water was added. The crystals that separated were isolated, washed with water, and dried. Their weight was 1.22 g (92.4%), m.p. 77.5–78°. After recrystallization (alcohol–benzene), 78–78.5°. A mixed sample with Va obtained by another route gave no melting-point depression.
\[ \begin{aligned} &\text{Found } \%:\ \mathrm{C}\ 55.5;\ 55.27;\ \mathrm{H}\ 7.97;\ 7.95\\ &\mathrm{C}_{16}\mathrm{H}_{26}\mathrm{O}_{8}.\ \text{Calculated } \%:\ \mathrm{C}\ 55.47;\ \mathrm{H}\ 7.56 \end{aligned} \]
Institute of Physico-Organic Chemistry
Academy of Sciences of the BSSR
Belorussian State University
named after V. I. Lenin
Received
5 V 1961
REFERENCES
- R. Criegee, W. Schnorrenberg, J. Becke, Ann., 565, 7 (1949).
- W. Cooper, W. H. T. Davidson, J. Chem. Soc., 1952, 1180.
- N. Brown, M. J. Hartig, M. J. Roedel, A. W. Anderson, C. E. Schweitzer, J. Am. Chem. Soc., 77, 1756 (1955).
- M. S. Kharasch, G. Sosnovsky, J. Org. Chem., 23, 1322 (1958).
- W. Cooper, J. Chem. Soc., 1951, 1340.
- A. A. Ol’dekop and K. L. Moiseichuk, Author’s Certificate 135484 (1960).
- Applications of Spectroscopy in Chemistry, IL, 1959.
- A. V. Karyakin, V. A. Nikitin, ZhFKh, 27, 1867 (1953).
- A. V. Karyakin, V. A. Nikitin, Izv. AN SSSR, ser. fiz., 17, 636 (1953).
* Determinations of active oxygen were carried out iodometrically analogously to (4).