Acrolein

Acrolein
Acrolein
Are common
Systematic ; name	Prop-2-en-1-al
Traditional names	Acrolein, Propenal, Acrylaldehyde
Chem. formula	C 3 H 4 O
Physical properties
Molar mass	56.0633 ± 0.003 g / mol
Density	0.843 g / cm³
Ionization energy	974.7911 kJ / mol
Thermal properties
T. melt.	−87 ° C
T. bale.	52.7 ° C
T. aux.	-26 ° C
T. svpl.	234 ° C
Etc. blast	2.8–31%%
Cr. point	232.85 ° C
Steam pressure	29 kPa (20 ° C)
Chemical properties
Solubility in water	200 g / 100 ml
Structure
Dipole moment	2,552 ± 0,003 (cis position), ; 3.117 ± 0.004 (trans position)
Classification
Reg. CAS number	107-02-8
PubChem
Reg. EINECS number	203-453-4
Smiles
Inchi
RTECS
Chebi
UN number
ChemSpider
Security
MPC	0.03 mg / m 3
LD 50	46 mg / kg (white rats, oral);; 7 mg / kg (rabbits, oral);; 28 mg / kg (mice, oral)
Toxicity	highly toxic, its vapors are especially dangerous, strong irritant, lacrimator;

Acrolein ( Latin acris - spicy, caustic + oleum - oil) (propenal) - H ₂ C = CH-CHO, acrylic acid aldehyde , the simplest unsaturated aldehyde . Colorless volatile tear liquid with a pungent odor, strong lacrimator .

Content

Reactivity

Acrolein, being a unsaturated aldehyde, exhibits the reactivity inherent to both olefins and aldehydes. So, acrolein forms acetals :

{\mathsf {H_{2}C{\text{=}}CH{\text{-}}CHO+H_{2}O\rightarrow H_{2}C{\text{=}}CHC{\text{-}}H(OH)_{2}}}

{\ displaystyle {\ mathsf {H_ {2} C {\ text {=}} CH {\ text {-}} CHO + H_ {2} O \ rightarrow H_ {2} C {\ text {=}} CHC { \ text {-}} H (OH) _ {2}}}}

its aldehyde group is easily oxidized to carboxyl:

{\mathsf {H_{2}C{\text{=}}CH{\text{-}}CHO{\xrightarrow[{}]{[O]}}H_{2}C{\text{=}}CH{\text{-}}COOH}}

{\ displaystyle {\ mathsf {H_ {2} C {\ text {=}} CH {\ text {-}} CHO {\ xrightarrow [{}] {[O]}} H_ {2} C {\ text { =}} CH {\ text {-}} COOH}}}

and reduced to hydroxyl:

{\mathsf {H_{2}C{\text{=}}C{\text{-}}CHO{\xrightarrow[{}]{[H]}}H_{2}C{\text{=}}CH{\text{-}}CH_{2}OH}}

{\ displaystyle {\ mathsf {H_ {2} C {\ text {=}} C {\ text {-}} CHO {\ xrightarrow [{}] {[H]}} H_ {2} C {\ text { =}} CH {\ text {-}} CH_ {2} OH}}}

The carbonyl group of acrolein is conjugated with a double bond , which leads to its high reactivity with respect to nucleophiles, while the addition proceeds at the β-carbon atom:

{\mathsf {H_{2}C{\text{=}}CH{\text{-}}CHO+HX\rightarrow XH_{2}C{\text{-}}CH_{2}{\text{-}}CHO\ \ \ X=OH,Hal,RO,RS}}

{\ displaystyle {\ mathsf {H_ {2} C {\ text {=}} CH {\ text {-}} CHO + HX \ rightarrow XH_ {2} C {\ text {-}} CH_ {2} {\ text {-}} CHO \ \ \ X = OH, Hal, RO, RS}}}

Halogens are attached to acrolein in a double bond to form a dihalogen derivative, which further cleaves the hydrogen halide to form α-halogenacrolein:

{\mathsf {H_{2}C{\text{=}}CH{\text{-}}CHO+Hal_{2}\rightarrow HalH_{2}C{\text{-}}CHHal-CHO}}

{\ displaystyle {\ mathsf {H_ {2} C {\ text {=}} CH {\ text {-}} CHO + Hal_ {2} \ rightarrow HalH_ {2} C {\ text {-}} CHHal-CHO }}}

{\mathsf {HalH_{2}C{\text{-}}CHHal-CHO\rightarrow H_{2}C{\text{=}}CHal{\text{-}}CHO+HHal}}

{\ displaystyle {\ mathsf {HalH_ {2} C {\ text {-}} CHHal-CHO \ rightarrow H_ {2} C {\ text {=}} CHal {\ text {-}} CHO + HHal}}}

Due to the presence of an electron-withdrawing aldehyde group conjugated to a double bond, acrolein is a dienophile and reacts with dienes with the formation of cycloaddition products ( Diels-Alder reaction ):

Synthesis

In the laboratory, acrolein is obtained by dehydration of glycerol in the presence of potassium hydrosulfate .

In industry, acrolein is produced by catalytic oxidation of propylene over bismuth oxide - molybdenum catalysts or copper oxide. Previously, the process of vapor-phase croton condensation of acetaldehyde with formaldehyde (an outdated method) was common in industry:

{\mathsf {CH_{2}O+CH_{3}CHO\rightarrow CH_{2}{\text{=}}CH{\text{-}}CHO+H_{2}O}}

{\ displaystyle {\ mathsf {CH_ {2} O + CH_ {3} CHO \ rightarrow CH_ {2} {\ text {=}} CH {\ text {-}} CHO + H_ {2} O}}}

Toxicity

Due to its high reactivity, acrolein is a toxic, highly irritating compound to the mucous membranes of the eyes and respiratory tract, a strong lacrimator . Maximum single maximum permissible concentration in the air 0.03 mg / m³; Average daily maximum permissible concentration in the air is 0.01 mg / m³ (MP list GN 2.1.6 1338-03). It causes mutagenesis in bacteria and yeast, exhibits mutagenic properties in mammalian cell cultures ^[1] .

Belongs to hazard class I (extremely hazardous substances).

Acrolein is one of the products of thermal decomposition of glycerol and glyceride fats, which explains the irritating mucous membranes properties of smoke of burnt fat.

Application

Used for the synthesis of acrylonitrile , glycerol , pyridine , β-picoline, amino acids ( methionine ), ethyl vinyl ethers, glutaraldehyde, polyacrolein. Also used in the manufacture of medicines. During the First World War it was used as a chemical weapon.

Literature

Chemical Encyclopedia / Editorial Board: Knunyants I.L. et al. - M .: Soviet Encyclopedia, 1988. - T. 1 (Abl-Dar). - 623 p.

Notes

↑ Acrolein MSDS ( unopened ) (inaccessible link) . Date of treatment March 26, 2012. Archived February 14, 2012.

[1] Acrolein MSDS ( unopened ) (inaccessible link) . Date of treatment March 26, 2012. Archived February 14, 2012.

Acrolein


Are common
Systematic name	Prop-2-en-1-al
Traditional names	Acrolein, Propenal, Acrylaldehyde
Chem. formula	C ₃ H ₄ O
Physical properties
Molar mass	56.0633 ± 0.003 g / mol
Density	0.843 g / cm³
Ionization energy	974.7911 kJ / mol
Thermal properties
T. melt.	−87 ° C
T. bale.	52.7 ° C
T. aux.	-26 ° C
T. svpl.	234 ° C
Etc. blast	2.8–31%%
Cr. point	232.85 ° C
Steam pressure	29 kPa (20 ° C)
Chemical properties
Solubility in water	200 g / 100 ml
Structure
Dipole moment	2,552 ± 0,003 (cis position), 3.117 ± 0.004 (trans position)
Classification
Reg. CAS number	107-02-8
PubChem
Reg. EINECS number	203-453-4
Smiles
Inchi
RTECS
Chebi
UN number
ChemSpider
Security
MPC	0.03 mg / m ³
LD ₅₀	46 mg / kg (white rats, oral); 7 mg / kg (rabbits, oral); 28 mg / kg (mice, oral)
Toxicity	highly toxic, its vapors are especially dangerous, strong irritant, lacrimator