Abstract Generated abstract
The study examines reactions of ethyl and phenyl dichlorophosphines with acrylic and methacrylic acids as a route to phosphorus-containing carboxylic acid chlorides. It proposes that addition begins with attack of the phosphorus lone pair at the beta carbon of the unsaturated acid, forming a bipolar intermediate and a 1:1 adduct that rearranges to acid chlorides of 4-oxo-4-chloro-4-phosphacarboxylic acids. The products are characterized by boiling points, densities, refractive indices, molar refractions, elemental analyses, and yields, with improved recovery by film distillation because ordinary distillation causes decomposition with phosgene liberation. Hydrolysis and alcoholysis reactions furnished the corresponding acids, esters, and related derivatives, including an anhydride byproduct and a dichloroisopropyl ester from epichlorohydrin.
Full Text
CHEMISTRY
V. K. KHAIRULLIN
REACTION OF ETHYLDICHLOROPHOSPHINE
WITH $\alpha,\beta$-UNSATURATED ACIDS
(Presented by Academician B. A. Arbuzov, 16 XI 1964)
Recently A. A. Petrov and co-workers studied the condensation reaction of glycolphosphorous acids with $\alpha,\beta$-unsaturated ketones (1). In October 1964 the same authors (2) reported the condensation of the aforementioned acid chlorides with various conjugated heteroatomic systems, including acrylic and methacrylic acids. The constants and properties of the substances obtained are not given by the authors. When we were studying the reactions of acid chlorides of trivalent phosphorus acids, the work of A. A. Petrov was not known to us.
The present paper reports on the interaction of aryl- and alkyldichlorophosphines with acrylic and methacrylic acids. The reaction of equimolecular amounts of ethyldichlorophosphine and acrylic or methacrylic acid proceeds with the evolution of heat. Phenyldichlorophosphine reacts with acrylic acid on heating. As a result of these reactions, the acid chlorides of 4-oxo-4-chloro-4-phosphacarboxylic acids are obtained.
The reaction proceeds according to the scheme (3):
$$ \mathrm{R{-}\overset{:}{P}\!\begin{matrix} /\,\mathrm{Cl}\\ \backslash\,\mathrm{Cl}\end{matrix}} + {}^{\delta+}\mathrm{CH_2{=}CR'} - \mathrm{\overset{\delta-}{C}\!\begin{matrix} //\,\mathrm{O}\\ \backslash\,\mathrm{OH}\end{matrix}} \longrightarrow \mathrm{R{-}\overset{+}{P}\!\begin{matrix} |\,\mathrm{Cl}\\ |\,\mathrm{Cl}\end{matrix}{-}CH_2{-}CR'{=}C\!\begin{matrix} /\,\mathrm{O^-}\\ \backslash\,\mathrm{OH}\end{matrix}} \longrightarrow $$
$$ \longrightarrow \mathrm{R{-}P\!\begin{matrix} |\,\mathrm{Cl}\\ |\,\mathrm{Cl}\end{matrix} \!\begin{matrix} /\,\mathrm{O{-}C{=}O}\\ \backslash\,\mathrm{CH_2{-}CR'}\end{matrix}} \longrightarrow \mathrm{R{-}P(=O)(Cl){-}CH_2{-}CHR'{-}CO{-}Cl} $$
$$ \text{(I)} \qquad \text{(II)} \qquad \text{(III)} \qquad \text{where } R=C_2H_5,\ C_6H_5;\quad R'=H,\ CH_3. $$
The unshared pair of electrons of phosphorus attacks the $\beta$-carbon atom of the $\alpha,\beta$-unsaturated acid. An intermediate bipolar ion (I) is formed, which passes into the 1 : 1 adduct (II), which rearranges into the acid chloride of 4-oxo-4-chloro-4-phosphacarboxylic acid (III).
Distillation of the acid chlorides of 4-oxo-4-chloro-4-phosphacarboxylic acids is accompanied by considerable decomposition with liberation of phosgene:
$$ n\mathrm{R{-}P(=O)(Cl){-}CH_2{-}CHR'{-}COCl} \rightarrow \left( -\mathrm{P(=O)(R){-}CH_2{-}CHR'}- \right)_n + n\mathrm{COCl_2}. $$
Therefore the yields of the products are low. However, if the reaction products are subjected to fractionation in an apparatus for film distillation, the yields of the acid chlorides increase considerably.
The constants of the acid chlorides of 4-oxo-4-chloro-4-phosphapropionic, 2-methyl-4-oxo-4-chloro-4-phosphapropionic, and 4-oxo-4-chloro-4-phenyl-4-phosphabutyric acids are presented in Table 1, Nos. 3, 4, 8.
Hydrolysis of the chloroanhydrides (Table 1, Nos. 3, 4) with water gave the corresponding acids (Table 1, Nos. 1, 2).
Reactions of the chloroanhydrides of 4-oxo-4-chloro-4-phosphacarboxylic acids with alcohols in the presence of triethylamine in ether give the corresponding
Table 1
Derivatives of 4-oxo-4-hydroxy-4-phosphacarboxylic acids
\[ \mathrm{X{-}\overset{O}{\overset{\Vert}{P}}(R){-}CH_2{-}CHR'{-}CO{-}X} \]
| No. | X | R | R′ | B.p., °C (pressure, mm Hg) | \(d_4^{20}\) | \(n_D^{20}\) | \(MR_D\), found | \(MR_D\), calculated | P, %, found | P, %, calculated | Cl, %, found | Cl, %, calculated | Yield, % |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | OH | \(\mathrm{C_2H_5}\) | H | a) | — | — | — | — | 18.30 | 18.22 | — | — | 84.5 |
| 2 | OH | \(\mathrm{C_2H_5}\) | \(\mathrm{CH_3}\) | b) | — | — | — | — | 16.69 | 17.20 | — | — | 92.5 |
| 3 | Cl | \(\mathrm{C_2H_5}\) | H | 118–120 (0.22) | 1.3412 | 1.4935 | 44.01 | 43.87 | 15.22 | 15.25 | 34.72 | 34.93 | 62.5 |
| 4 | Cl | \(\mathrm{C_2H_5}\) | \(\mathrm{CH_3}\) | 116–117 (0.2) | 1.2817 | 1.4875 | 48.75 | 48.49 | 14.49 | 14.27 | 32.51 | 32.67 | 37.2 |
| 5 | \(\mathrm{OCH_3}\) | \(\mathrm{C_2H_5}\) | H | 103–104 (0.22) | 1.1480 | 1.4510 | 45.54 | 45.92 | 15.68 | 15.95 | — | — | 57.5 |
| 6 | \(\mathrm{OC_2H_5}\) | \(\mathrm{C_2H_5}\) | H | 116–118 (0.22) | 1.0761 | 1.4550 | 55.06 | 55.15 | 13.62 | 13.94 | — | — | 54.5 |
| 7 | \(\mathrm{OC_2H_5}\) | \(\mathrm{C_2H_5}\) | \(\mathrm{CH_3}\) | 86–87 (0.07) | 1.0536 | 1.4440 | 59.56 | 59.78 | 12.96 | 13.11 | — | — | 50.0 |
| 8 | Cl | \(\mathrm{C_6H_5}\) | H | 114–116 (0.002) | 1.3840 | 1.5595 | 58.61 | 58.74 | 13.00 | 12.34 | 29.00 | 28.24 | 10.5 |
| 9 | \(\mathrm{OCH(CH_2Cl)_2}\) | \(\mathrm{C_2H_5}\) | H | 237 (0.002) c) | 1.3668 | 1.4970 | 83.08 | 83.86 | 7.63 | 7.98 | 37.53 | 36.55 | 46.5 |
a) M.p. 99.5°. b) M.p. 40–43°. c) At this temperature the product distilled over with considerable decomposition.
esters (Table 1, Nos. 5, 6, 7). It should be noted that during distillation of the crude reaction products, thick, oily liquids remain in the distillation flask. In the case of the reaction of 2-methyl-4-oxo-4-chloro-4-phosphacaproyl chloride with ethyl alcohol, the anhydride of ethyl 2-carbethoxyisopropylphosphinic acid was isolated from this residue:
\[ \mathrm{ C_2H_5OC(=O){-}CH(CH_3){-}CH_2{-}P(=O)(C_2H_5){-}O{-}P(=O)(C_2H_5){-}CH_2{-}CH(CH_3){-}COC_2H_5 } \]
B.p. 175–177° at 0.1 mm Hg; \(d_4^{20}\) 1.1383; \(n_D^{20}\) 1.4670; \(MR_D\) found 97.10; calculated 96.24.
\[ \mathrm{C_{16}H_{32}O_7P_2.} \quad \begin{array}{ll} \text{Found, \%:} & \mathrm{C}\ 48.23;\ \mathrm{H}\ 8.25;\ \mathrm{P}\ 15.52 \\ \text{Calculated, \%:} & \mathrm{C}\ 48.23;\ \mathrm{H}\ 8.10;\ \mathrm{P}\ 15.55 \end{array} \]
The product is titrated by two equivalents of alkali.
The chloroanhydride of 4-oxo-4-chloro-4-phosphacapronic acid with epichlorohydrin also gives the 1,3-dichloroisopropyl ester (Table 1, No. 9).
Institute of Organic Chemistry
Academy of Sciences of the USSR
Kazan
Received
14 XI 1964
CITED LITERATURE
- N. A. Razumova, A. A. Petrov, DAN, 158, 907 (1964).
- A. A. Petrov, N. A. Razumova, A. Kh. Voznesenskaya, ZhOKh, 34, 3512 (1964).
- G. Kamai, V. A. Kukhtin, DAN, 109, 91 (1956).