Epichlorohydrin

Epichlorohydrin
Epichlorohydrin
Are common
Systematic ; name	2-chloromethyloxyran
Traditional names	Epichlorohydrin; 3-chloro-1,2-epoxypropane,; chloromethyloxyran
Chem. formula	C 3 H 5 ClO
Rat formula	CH 2 -O-CH-CH 2 Cl
Physical properties
condition	colorless liquid with an irritating smell of chloroform
Molar mass	92.524 ± 0.005 g / mol
Density	1,18066 g / cm³
Ionization energy
Thermal properties
T. melt.	-48 ° C
T. bale.	117.9g ° C
T. aux.	40.6 ° C
T. svpl.	415.6 ° C
Etc. blast
Steam pressure	13.1 mmHg Art. (20 ° C),
Chemical properties
Solubility in water	6.5 g / 100 ml
Optical properties
Refractive index	1.43805
Classification
Reg. CAS number	106-89-8
PubChem
Reg. EINECS number	203-439-8
Smiles
Inchi
RTECS
Chebi
ChemSpider
Security
MPC	1 mg / m 3
LD 50	90 mg / kg (rat, oral)
Toxicity	Highly toxic substance, highly irritating to the mucous membranes of the respiratory tract ( irritant ).;
NFPA 704	3 3 2

Epichlorohydrin (chloromethyloxyran) is an organic substance , a chlorine derivative of propylene oxide, with the formula CH ₂ (O) CH-CH ₂ Cl. It is widely used in organic synthesis, used in the production of epoxies and glycerol ^[2] . Highly toxic, irritant .

Synthesis

Epichlorohydrin is obtained from propylene , which is chlorinated at a temperature of 500 ° C and a pressure of 18 atm. to allyl chloride:

{\mathsf {CH_{3}CH{=}CH_{2}+Cl_{2}\rightarrow ClCH_{2}CH{=}CH_{2}+HCl}}

{\ displaystyle {\ mathsf {CH_ {3} CH {=} CH_ {2} + Cl_ {2} \ rightarrow ClCH_ {2} CH {=} CH_ {2} + HCl}}}

{\mathsf {CH_{3}CH{=}CH_{2}+Cl_{2}\rightarrow ClCH_{2}CH{=}CH_{2}+HCl}}

Then, allyl chloride is exposed to hypochlorous acid and the isomeric dichlorohydrins of glycerol are obtained:

Further, glycerol dichlorohydrins act with alkali ( NaOH ), resulting in the formation of epichlorohydrin: ^[3]

The resulting epichlorohydrin is separated by steam distillation and distillation . It can also be obtained by reduction of chlorinated acrolein ^[4] .

Physical Properties

It is a colorless mobile transparent liquid with an irritating smell of chloroform , poorly soluble in water , good in most organic solvents. It forms an azeotropic mixture with water with a boiling point of 88 ° C and contains 75% epichlorohydrin. Forms azeotropic mixtures with a large number of organic liquids. Due to the presence of an asymmetric carbon atom, epichlorohydrin is optically active ^[4] .

Chemical Properties

Epichlorohydrin is a chemically highly reactive compound having an active epoxy group and a mobile chlorine atom ^[5] .

Halogenation reaction

During the interaction of chlorine with epichlorohydrin under ordinary conditions, 3,3-dichloropropylene oxide (3,3-dichloroepoxypropylene) is formed ^[5] :

{\mathsf {CH_{2}CH{-}O{-}CH_{2}Cl+Cl_{2}\rightarrow CH_{2}CH{-}O{-}CHCl_{2}+HCl}}

{\ displaystyle {\ mathsf {CH_ {2} CH {-} O {-} CH_ {2} Cl + Cl_ {2} \ rightarrow CH_ {2} CH {-} O {-} CHCl_ {2} + HCl} }}

Hydrochlorination reaction

Easily attaches hydrogen chloride at ordinary temperature both in solution and in an anhydrous medium, with the formation of 1,3-dichlorohydrin ^[5] :

{\mathsf {CH_{2}CH{-}O{-}CH_{2}Cl+HCl\rightarrow CH_{2}Cl{-}CHOH{-}CH_{2}Cl}}

{\ displaystyle {\ mathsf {CH_ {2} CH {-} O {-} CH_ {2} Cl + HCl \ rightarrow CH_ {2} Cl {-} CHOH {-} CH_ {2} Cl}}}

Dehydrochlorination reaction

In the presence of small amounts of alkali, epichlorohydrin easily joins compounds containing one or more mobile hydrogen atoms, with the formation of chlorohydrins ^[5] :

{\mathsf {RH+CH_{2}CH{-}O{-}CH_{2}Cl{\xrightarrow[{}]{[NaOH]}}RCH_{2}{-}CHOH{-}CH_{2}Cl}}

{\ displaystyle {\ mathsf {RH + CH_ {2} CH {-} O {-} CH_ {2} Cl {\ xrightarrow [{}] {[NaOH]}} RCH_ {2} {-} CHOH {-} CH_ {2} Cl}}}

With an increase in alkali concentration, the reaction proceeds with the removal of hydrogen chloride and with the restoration of the epoxy group, but in a different position ^[5] :

{\mathsf {RCH_{2}{-}CHOH{-}CH_{2}Cl{\xrightarrow[{}]{[NaOH]}}RCH_{2}{-}CH{-}O{-}CH_{2}}}

{\ displaystyle {\ mathsf {RCH_ {2} {-} CHOH {-} CH_ {2} Cl {\ xrightarrow [{}] {[NaOH]}} RCH_ {2} {-} CH {-} O {- } CH_ {2}}}}

Hydrolysis reaction

With an excess of alkali ( sodium carbonate is most often used) and at a temperature of 100 ° C, epichlorohydrin slowly turns into glycerol ^[5] :

{\mathsf {2CH_{2}CH{-}O{-}CH_{2}Cl+NaCO_{3}+3H_{2}O{\xrightarrow {100{^{o}C}}}2CH_{2}OH{-}CHOH{-}CH_{2}OH+2NaCl+CO_{2}}}

{\ displaystyle {\ mathsf {2CH_ {2} CH {-} O {-} CH_ {2} Cl + NaCO_ {3} + 3H_ {2} O {\ xrightarrow {100 {^ {o} C}}} 2CH_ {2} OH {-} CHOH {-} CH_ {2} OH + 2NaCl + CO_ {2}}}}

Hydration reaction

in the presence of dilute inorganic acids ( sulfuric or phosphoric ), epichlorohydrin forms α-monochlorohydrin of glycerol ^[5] :

{\mathsf {CH_{2}CH{-}O{-}CH_{2}Cl+H_{2}O{\xrightarrow[{}]{[H_{2}SO_{4}]}}CH_{2}OH{-}CHOH{-}CH_{2}Cl}}

{\ displaystyle {\ mathsf {CH_ {2} CH {-} O {-} CH_ {2} Cl + H_ {2} O {\ xrightarrow [{}] {[H_ {2} SO_ {4}]}} CH_ {2} OH {-} CHOH {-} CH_ {2} Cl}}}

With increasing temperature, the hydration of epichlorohydrin increases.

Esterification reaction

During the interaction of epichlorohydrin with alcohols , the epoxy ring opens with the formation of a hydroxyl group in position 2 and with the formation of an ether ^[5] :

{\mathsf {CH_{2}CH{-}O{-}CH_{2}Cl+HOR\rightarrow ClCH_{2}{-}CHOH{-}CH_{2}OR}}

{\ displaystyle {\ mathsf {CH_ {2} CH {-} O {-} CH_ {2} Cl + HOR \ rightarrow ClCH_ {2} {-} CHOH {-} CH_ {2} OR}}}

With carboxylic acids, epichlorohydrin forms chlorohydrin esters, for example with glacial acetic acid, when heated to 180 ° C, predominantly 1-chloro-2-hydroxy-3-propyl acetate is formed ^[5] :

{\mathsf {CH_{2}CH{-}O{-}CH_{2}Cl+CH_{3}COOH\rightarrow ClCH_{2}{-}CHOH{-}CH_{2}COOCH_{3}}}

{\ displaystyle {\ mathsf {CH_ {2} CH {-} O {-} CH_ {2} Cl + CH_ {3} COOH \ rightarrow ClCH_ {2} {-} CHOH {-} CH_ {2} COOCH_ {3 }}}}

Amination reaction

Epichlorohydrin already at normal temperature joins ammonia or amines with the opening of the cycle ^[5] :

{\mathsf {CH_{2}CH{-}O{-}CH_{2}Cl+NH_{3}\rightarrow NH_{2}{-}CH_{2}{-}CHOH{-}CH_{2}Cl}}

{\ displaystyle {\ mathsf {CH_ {2} CH {-} O {-} CH_ {2} Cl + NH_ {3} \ rightarrow NH_ {2} {-} CH_ {2} {-} CHOH {-} CH_ {2} Cl}}}

Condensation reaction

Epichlorohydrin reacts with diphenylolpropane to form a polymeric diglycidyl ether ^[5] :

This reaction is an example of the preparation of epoxy resins , which have recently become very widespread due to their exceptional properties ^[5] .

Polymerization reaction

Epichlorohydrin is able to polymerize. Depending on the catalyst used, mobile liquids, highly viscous oils or resinous products are obtained ^[5] .

Application

It is used as an intermediate for the synthesis of glycerol derivatives, dyes, and surfactants ; for synthetic materials (mainly epoxies ).

Toxicology and Safety

General nature of the action

It has an irritating and allergic effect. In animal experiments, the kidneys are selectively affected. Penetrates through the skin ^[2] .

Epichlorohydrin is a highly toxic and flammable compound ^[4] . Vapors of epichlorohydrin, when inhaled even in small concentrations, cause nausea , dizziness and lacrimation , and with prolonged exposure lead to more serious consequences (often severe pulmonary edema occurs) ^[2] . Epichlorohydrin, upon contact with the skin and prolonged contact, causes dermatitis, up to superficial necrosis. All work with epichlorohydrin must be carried out with rubber gloves, a rubber apron, and with strong gas contamination in pairs, in a gas mask of grade A ^[6] .

Security

Epichlorohydrin is a flammable substance. In case of fire, extinguish with carbon dioxide, foam or water, evenly distributing it on the surface. MPC in the air of the working area of industrial premises should not exceed 1 mg / m ³ , MPC in the atmospheric air of populated areas 0.2 mg / m ³ (recommended) ^[5] .

Notes

↑ ¹ ² http://www.cdc.gov/niosh/npg/npgd0254.html
↑ ¹ ² ³ Harmful substances in industry. Handbook for chemists, engineers and doctors. Ed. 7th, per. and add. In three volumes. Volume I. Organic matter. Ed. merit activist science prof. N.V. Lazareva and Dr. honey. Sciences E.N. Levina. L., “Chemistry,” 1976. 592 pp., 27 tablets, bibliography — 1850 titles.
↑ Grigoriev A.P., Fedotova O.Ya. Laboratory workshop on plastics technology. In two parts. Part 2. Polycondensation and chemically modified plastics. - Textbook. allowance for chemical technol. universities. - 2nd ed., Revised. and additional .. - M .: Higher school, 1977. - T. 2. - 264 p.
↑ ¹ ² ³ Goldberg M.M. Ermolaeva T.A., Livshits M.L., Lubman A.M., Rassudova N.S., Sergeeva 3.I., Fartunin V.I. Raw materials and intermediates for paints and varnishes / Ed. M.M. Goldberg .. - M .: Chemistry, 1978. - 512 p.
↑ ¹ ² ³ ⁴ ⁵ ⁶ ⁷ ⁸ ⁹ ¹⁰ ¹¹ ¹² ¹³ ¹⁴ Oshin L.A. Industrial organochlorine products. - M .: Chemistry, 1978.- 656 p.
↑ Bratsykhin E.A., Shulgina E.S. Technology of plastics. - A manual for technical schools. - 3rd ed., Revised. and additional .. - L .: Chemistry, 1982. - 328 p.