Acrylamide

description

Acrylamide is a white crystalline chemical substance and is a raw material for production of polyacrylamide. Solid acrylamide (abbreviated AM) is usually colorless and transparent flaky crystals with pure product being white crystalline solid which is soluble in water, methanol, ethanol, propanol, and slightly soluble in ethyl acetate, chloroform, and benzene. It can be hydrolyzed to acrylic acid in acidic or alkaline environment.
Acrylamide is a large class of the parent compound of monomers including methacrylamide, the AMPS (anionic monomer, 2-Acraylamide-2-Methyl Propane Sulfonic Acid), the DMC (cationic monomer, methyl-acryloyloxyethyl trimethyl ammonium chloride) and N-substituted acrylamide compound.

Occupational exposure is mainly seen in acrylamide production and the synthesis of resins, adhesives, etc. It is also possible for contract in underground construction, upon soil improvement, painting, paper industry and garment processing.
At daily life, people can touch it in smoking, drinking and eating the starchy foods processed at high temperature.

Chemical Properties

Acrylamide is odorless and colorless crystal. It is soluble in water, ethanol, acetone, ether, and methyl chloroform, and slightly soluble in toluene but insoluble in benzene. Acrylamide is a water-soluble monomer with two reactive centers (a vinyl group - with its reactive double bond, and an amide group). Because of its high reactivity, aqueous acrylamide monomer is stabilized with dissolved cupric salts and oxygen to prevent polymerization during shipping and storage.

Synthesis

At the end of 19th century, people had first made acrylamide using propylene chloride and ammonia.
In 1954, American Cyanamid Company uses sulfuric acid hydrolysis of acrylonitrile for industrial production.
In 1972, Mitsui Toatsu Chemicals, Inc. had first established the skeleton copper (see the metal catalyst) catalyzed acrylamide synthesis via acrylonitrile hydration. Then other countries have developed different types of catalyst and applied this technology for industrial production.
In 1980s, Japanese Nitto Chemical Industry Company has achieved that using biological catalyst for industrial production of acrylamide from acrylonitrile.
Sulfuric acid hydration way
Acrylonitrile and water is hydrolyzed into acrylamide sulfate in the presence of sulfuric acid and then treated neutralized liquid ammonia to give ammonium sulfate and acrylamide:
CH2 = CHCN + H2O + H2SO4 → CH2 = CHCONH2 • H2SO4 CH2 = CHCONH2 • H2SO4 + 2NH3→ CH2 = CHCONH2 + (NH4) 2SO4
The disadvantage of this method is by-producing a large number of low-value, low fertilizing efficacy-ammonium sulfate and causing serious sulfuric acid corrosion and pollution.
Catalytic hydration way
Acrylonitrile is reacted with water by the copper-based catalyst to have liquid phase hydration reaction at 70~120 °C at 0.4MPa pressure.
CH2 = CH-CN + H2O → CH2 = CHCONH2; Filter the catalyst after reaction catalyst; recycle the unreacted acrylonitrile; acrylamide solution was concentrated and cooled to give crystals. This is a simple method with the yield up to 98%.

Polymerization

For polymerization of acrylamide, people generally applies chemical catalytic systems or photocatalytic systems.
(1) Chemical catalyst system: chemical catalytic polymerization of acrylamide is done in the systems containing the trigger and accelerator. Trigger reagents participating the reaction include ammonium persulfate (or potassium persulfate) and hydrogen peroxide while the accelerator includes dimethylamine propionitrile and so on. Because the polymerization of acrylamide can performed under both acidic or alkaline conditions, so the choice of trigger and accelerator should be changed with pH.
When the aqueous solution of acrylamide (Arc), cross-linking agent (Bis) and tetramethylethylenediamine (tetramethyl ethylene diamine, TEMED) is added into ammonium persulfate (ammoniumpersulfate, AP), AP [(NH4) 2S20s] immediately generate radical (S: OU-2S07), after the reaction between Arc and the free radicals, then it becomes "activate", activated Arc connects with each other to form a long chain poly. The solution containing this polymer chain, although is sticky but can’t form a gel and can form into a gel only when Bis is also presented. In the AP-TEMED catalyzed system, the initiating polymerization rate between Arc and Bis is positively proportional to the square root of the concentration of AP and can occur rapidly under alkaline conditions. For example, the complete polymerization of 7% Arc, only needs 0.5 h upon pH8.8; however, needs 1.5 h upon pH4.3. In addition, temperature, oxygen molecules and other impurities will also affect the rate of polymerization. Usually faster polymerization occurs at room temperature than at 0 °C; Solution subjecting to pre-pumping also has faster polymerization rate than that without pre-puming.
(2) Photocatalytic System: This catalysis of this system is vitamin B2. Photo-polymerization process is catalyzed at light excitation. Vitamin B: in the presence of oxygen and ultraviolet light, can produce products containing free radicals whose function is similar as AP agent described above. The mixture is usually placed next to a fluorescent lamp where the reaction can take place. When using Vitamin B2 for catalyzing, TEMED is not demaned, but adding it can accelerate the rate of polymerization. Gel formed by photo-polymerization is milky white like with poor transparency. The advantage of using this catalyst is that it needs a very small amount (1ml/100mi) without any adverse effect on the analysis of samples; polymerization time can be extended or shortened by chaning the light intensity and time.
The apertube of chemical polymerization is smaller thant that of photo-polymerization. The reproducibility and transparency is also better for the former one than the latter one. However, the trigger of the chemical polymerization, AP, is a strong oxidizing agent, tend to cause loss of activity of certain protein molecules if remaining in the gel or cause distortion on the electrophoresis pattern.

Uses

1. It can be used as a monomer of polyacrylamide. Its polymer or copolymer is used as chemical grouting materials, soil conditioners, flocculants, adhesives and coatings.
2. Polyacrylamide, when used as a kind of additive, can improve the oil recycling efficiency. When used as flocculants, it can be used for sewage treatment. It can also be used as a paper strength agent.
3. Acrylamide is the most important products in acrylamide and methacrylamide-based products. Since its application in industry in 1954, the demand gradually increase. It is mainly used for the preparation of water soluble polymers which can be used as additives to improve oil recovery; as a flocculant, thickening agents, and paper additives. A small amount of acrylamide is introduce the hydrophilic center into the lipophilic polymer to improve the viscosity, increase the softening point and improve anti-solvents ability of resin, and can aso introduce a center for the coloring property of dye. Acrylamide is also often used as a component of the photopolymer. For the vinyl polymer, its crosslinking reaction can take advantage of this kind of reactive amide groups. Acrylamide can co-polymerizze with certain monomers such as vinyl acetate, styrene, vinyl chloride, vinylidene chloride, and acrylonitrile to obtain a polymer with a variety of applications.
The main application areas: (1) used for the oilfield; the materials can be used in oilfield injection of wells for adjustment of the injection profile. Mix this product with initiator, and deaerator and inject into the high permeability layer part of water wells. This will lead the formation of high-viscosity polymer unearth of the stratum. This can plug the large pore, increase the swept volume of oil, and enhance the oil recovery. In addition, the product polymer or copolymer can be used for tertiary oil recovery, fracturing, water shutoff, drilling mixing process and chemical grouting. (2) It can be used as flocculants. Its partially hydrolyzed product and its graft copolymer of methyl cellulose can be used in wastewater treatment and sewage treatment. (3) Soil conditioner; using the hydrolyzed product as soil amendments can aggregate soil and can improve air circulation, water permeability and water retention. (4) Modification of fiber and resin processing; using acrylamide for carbamylation or graft polymerization can improve the resin arrangement of a variety of fiber containing synthetic fiber, as well as for warp and printing paste in order to improve the basic physical properties of fabrics as well as preventing wrinkle, shrink and keeping a good hand feeling. (5) It can be used as paper enhancer; copolymer of acrylamide and acrylic acid or partial hydrolysis products of polyacrylamide can be used as paper strength reinforcing agent for either replacing or combining with starch, and water-soluble amino resin. (6) it can be used as an adhesive agent including glass fiber adhesive agent with the combination of phenolic resin and polyacrylamide solution, as well as pressure sensitive adhesive combined with synthetic rubber.
4. It is the raw material for producing polyacrylamide and related products.
5. It can be used as the monomer of polyacrylamide. Its polymer or copolymer can be used as chemical grouting materials, soil conditioners, flocculants, adhesives and coatings. Polyacrylamide, as an additive, can improve oil recovery. As a kind of flocculants, it can be used for waste water treatment as well as paper strength enhancer can. It is the raw material for producing polyacrylamide and related products. It can also used for determining the relative molecular weight of acid.

Toxicity

LD50 i.p. in mice: 170 mg/kg (Peterson, Sheth)

Production methods

1. Acrylonitrile sulfate hydration; Acrylonitrile and water is hydrolyzed into acrylamide sulfate in the presence of sulfuric acid and then treated neutralized liquid ammonia to give ammonium sulfate and acrylamide: The reaction products further undergoes filtering and separation. Crystallize the filtrate, dry to obtain the final product. The disadvantage of this method is by-producing a large number of low-value, low fertilizing efficacy-ammonium sulfate and causing serious sulfuric acid corrosion and pollution. This method can produce by-products of 2280 kg ammonium sulfate in per tons of acrylonitrile.Material consumption amount: Acrylonitrile (100%) 980kg/t, sulfuric acid (100%) 200kg/t, ammonia (100%) 700kg/t.
2. Direct hydration of acrylonitrile: acrylonitrile is directly hydrated by water with copper being the catalyst at 85-125 °C and 0.3-0.4MPa pressure. The yielding aqueous solution of acrylamide (containing only small amounts of by-products) can be directly sold as a finished product. This method avoids acrylamide dust pollution and is advantageous for labor protection for using aqueous solution. Reference Product Specifications: appearance: white flakes or powder. With first-grade product containing content ≥95%; Secondary-grade content ≥90%; grade III content ≥85%.
3. Enzyme catalysis; at room temperature transfer the acrylonitrile solution into the fixed-bed reactor containing bacteria catalyst; after the reaction, 100% of acrylonitrile is converted into acrylamide. After isolation and even without the necessity of refining and concentration, we can get the acrylamide industrial products.
4. Concentrated sulfuric acid hydration method: mixture containing sulfate, phenothiazine (polymerization inhibitor), and water is added to the reactor; stir slowly with dropping acrylonitrile After the addition is completed, raise the temperature to 95~100 °C, keep the temperature for 50 min. Cool to 20~25 °C, dilute with an appropriate amount of water, neutralize with sodium carbonate, filtrate to obtain aqueous acrylic acid solution. Further cool and crystallize, separate, dry to obtain the completed products.
5. Catalytic hydration method; acrylonitrile and water undergoes liquid phase hydration in the presence of copper-based catalyst; It is generally used for continuous production with the reaction temperature being 85~120 °C, reaction pressure being 0.29~0.39 MPa, feed concentration of 6.5%, airspeed being 5 L/ h, the conversion rate being 85%, and selectivity being about 95% and the concentration of acrylamide in the reaction being 7% to 8%. Aqueous solution obtained by this method may be directly used as the product for sale.

Description

Acrylamide is an odorless, white crystalline solid that initially was produced for commercial purposes by reaction of acrylonitrile with hydrated sulfuric acid.
Acrylamide exists in two forms: a monomer and a polymer. Monomer acrylamide readily participates in radicalinitiated polymerization reactions, whose products form the basis of most of its industrial applications. The single unit form of acrylamide is toxic to the nervous system, a carcinogen in laboratory animals and a suspected carcinogen in humans. The multiple unit or polymeric form is not known to be toxic.
Acrylamide is formed as a by-product of the Maillard reaction. The Maillard reaction is best known as a reaction that produces pleasant flavor, taste, and golden color in fried and baked foods; the reaction occurs between amines and carbonyl compounds, particularly reducing sugars and the amino acid asparagine. In the first step of the reaction, asparagine reacts with a reducing sugar, forming a Schiff’s base. From this compound, acrylamide is formed following a complex reaction pathway that includes decarboxylation and a multistage elimination reaction. Acrylamide formation in bakery products, investigated in a model system, showed that free asparagine was a limiting factor. Treatment of flours with asparaginase practically prevented acrylamide formation. Coffee drinking and smoking are other major sources apart from the human diet.

Chemical Properties

Acrylamide, in monomeric form, is an odorless, flake-like crystals which sublime slow at room temperature. May be dissolved in a flammable liquid.

Uses

In the production of polyacrylamides, which are used in water and waste treatment, paper and pulp processing, cosmetic additives, and textile processing; in adhesives and grouts; as cross-linking agents in vinyl polymers

Uses

Acrylamide contained in polyacrylamide gels used for electrophoresis caused contact dermatitis in laboratory workers.

Uses

Over 90% of acrylamide is used to make polyacrylamides (PAMs), and the remaining 10% is used to make N-methylolacrylamide (NMA) and other monomers. Water treatment PAMs consumed 60% of the acrylamide; PAMs for pulp and paper production consume 20% of the acrylamide; and PAMs for mineral processing consume 10% of the acrylamide. Some of the specific uses of acrylamide are:
In liquid-solid separation where acrylamide polymers act as flocculants and aids in mineral processing, waste treatment and water treatment. They also help reduce sludge volumes in these applications.
As additives in the manufacture of paper and paper board products, leather and paint industries. In the paper industry PAMs act as retention aids during wet end processing and in wet strength additives.
In the manufacture of synthetic resins for pigment binders for textile/leather industries, and In enhanced oil recovery.
use in protein electrophoresis (PAGE), synthesis of dyes and copolymers for contact lenses. It is reasonably anticipated to be a hum an carcinogen.

Definition

ChEBI: A member of the class of acrylamides that results from the formal condensation of acrylic acid with ammonia.

Definition

acrylamide: An inert gel (polyacrylamide)employed as a medium inelectrophoresis. It is used particularlyin the separation of macromolecules,such as nucleic acids and proteins.

Preparation

The principal synthetic route to making acrylamide involves the hydration of acrylonitrile (ACRN). In this process an aqueous ACRN solution reacts over a copper-oxide-chromium oxide catalyst at approximately 100°C. Several other catalyst systems have been used, and most of them contain copper - in some form. The reaction step is followed by purification and concentration to a 50% solution in a vacuum evaporator. The yield of acrylamide from ACRN is 98%. The purification and concentration steps are costly and also involve the recycle of ACRN back to the reaction step. In the early part of the new century, a catalytic distillation process has been developed that converts almost 100% of the ACRN to acrylamide and allows concentration to occur in the same column where acrylamide is made. Therefore this process is less costly.
Nitto Chemical (now Dia-Nitrix) introduced a biosynthetic route from ACRN to acrylamide in Japan in 1985. This process uses an immobilized nitrile hydratase biocatalyst that converts the ACRN solution to acrylamide with a yield of 99.5%. This high yield allows a concentrated acrylamide solution to be made without the need for ACRN recycle or solution concentration. This process therefore has lower energy costs.

General Description

A solution of a colorless crystalline solid. Flash point depends on the solvent but below 141°F. Less dense than water. Vapors heavier than air. Toxic oxides of nitrogen produced during combustion. Used for sewage and waste treatment, to make dyes and adhesives.

Air & Water Reactions

Acrylamide is very soluble in water. The solvent is not necessarily water soluble.

Reactivity Profile

ACRYLAMIDE SOLUTION reacts with azo and diazo compounds to generate toxic gases. Flammable gases are formed with strong reducing agents. Combustion generates mixed oxides of nitrogen (NOx). Spontaneous, violent polymerization occurs at the melting point (86°C of the undissolved solid [Bretherick, 5th ed., 1995, p. 428].

Health Hazard

The acute toxicity of acrylamide is moderate by ingestion or skin contact. Skin exposure leads to redness and peeling of the skin of the palms. Aqueous acrylamide solutions cause eye irritation; exposure to a 50% solution of acrylamide caused slight corneal injury and slight conjunctival irritation, which healed in 8 days. The chronic toxicity of acrylamide is high. Repeated exposure to ~2 mg/kg per day may result in neurotoxic effects, including unsteadiness, muscle weakness, and numbness in the feet (leading to paralysis of the legs), numbness in the hands, slurred speech, vertigo, and fatigue. Exposure to slightly higher repeated doses in animal studies has induced multisite cancers and reproductive effects, including abortion, reduced fertility, and mutagenicity. Acrylamide is listed in IARC Group 2B ("possible human carcinogen") and is classified as a "select carcinogen" under the criteria of the OSHA Laboratory Standard.

Flammability and Explosibility

The volatility of acrylamide is low (0.03 mmHg at 40 °C), and it does not pose a significant flammability hazard.

Chemical Reactivity

Reactivity with Water No reaction; Reactivity with Common Materials: Data not available; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: May occur at temperature above 50°C (120°F); Inhibitor of Polymerization: Oxygen (air) plus 50 ppm of copper as copper sulfate.

Contact allergens

Acrylamide is used in the plastic polymers industry for water treatments and soil stabilization and to prepare polyacrylamide gels for electrophoresis. This neurotoxic, carcinogenic, and genotoxic substance is known to have caused contact dermatitis in industrial and laboratory workers

Biochem/physiol Actions

Acrylamide is a reactive, water soluble vinyl monomer. It causes a decrease in the number of neuritis per cell as well as reduces the rate of protein synthesis.

Safety Profile

Confirmed carcinogen with experimental carcinogenic and neoplastigenic data. Poison by ingestion, skin contact, and intraperitoneal routes. Experimental reproductive effects. Mutation data reported. A skin and eye irritantIntoxication from it has caused a peripheral neuropathy, erythema, and peeling palms. In industry, intoxication is mainly via dermal route, next via inhalation, and last via ingestion. Time of onset varied from 1-24 months to 8 years. Symptoms were, via dermal route, a numbness, tingling, and touch tenderness. In a couple of weeks, coldness of extremities; later, excessive sweating, bluish-red and peeling palms, marked fatigue and limb weakness. It is dangerous because it can be absorbed through the unbroken skin. From animal experiments it seems to be a central nervous system toxin. Adult rats fed an average of 30 mg/kg for 14 days were all partially paralyzed and had reduced their food consumption by 50 percent. Polymerizes violently at its melting point. When heated to decomposition it emits acrid fumes and NOX,.

Potential Exposure

Added to water during sewage/wastewater treatment. Used in the manufacture of plastics, resins, rubber, synthetic textiles; as a dye, pigment. A major application for monomeric acrylamide is in the production of polymers as polyacrylamides. Polyacrylamides are used for soil stabilization, gel chromatography, electrophoresis, papermaking strengtheners, clarifications, and treatment of potable water and foods.

Carcinogenicity

Acrylamide is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.

Environmental Fate

Biological. Bridié et al. (1979) reported BOD and COD values of 0.05 and 1.33 g/g using filtered effluent from a biological sanitary waste treatment plant. These values were determined using a standard dilution method at 20 °C for a period of 5 d. When a sewage seed was used in a separate screening test, a BOD value of 0.92 g/g was obtained. In a treatment plant, a BOD value of 0.40 g/g was reported after 10 d (Mills et al., 1953). The ThOD for acrylamide is 1.35 g/g.
Soil. Under aerobic conditions, acrylamide degraded to ammonium ions which oxidized to nitrite ions and nitrate ions. The ammonium ions produced in soil may volatilize as ammonia or accumulate as nitrite ions in sandy or calcareous soils (Abdelmagid and Tabatabai, 1982).
Chemical/Physical. Readily polymerizes at the melting point or under UV light. In the presence of alkali, polymerization is a violent reaction. On standing, may turn to yellowish color (Windholz et al., 1983).

storage

In particular, this substance should be handled only when wearing appropriate impermeable gloves to prevent skin contact, and all operations that have the potential of producing acrylamide dusts or aerosols of solutions should be conducted in a fume hood to prevent exposure by inhalation.

Shipping

UN2074 Acrylamide, Hazard Class: 6.1; Labels: 6.1-Poisonous materials

Purification Methods

Crystallise acrylamide from acetone, chloroform, ethyl acetate, methanol or *benzene/chloroform mixture, then vacuum dry and store it in the dark under vacuum. Recrystallise it from CHCl3 by dissolving 200g in 1L, heating to boiling and filtering without suction in a warmed funnel through Whatman 541 filter paper; allowing to cool to room temperature and keeping at -15o overnight. The crystals are collected with suction in a cooled funnel and washed with 300mL of cold MeOH. The crystals are air-dried in a warm oven. [Dawson et al. Data for Biochemical Research, Oxford Press 1986 p. 449, Beilstein 2 IV 1471.] CAUTION: Acrylamide is extremely TOXIC (neurotoxic), and precautions must be taken to avoid skin contact or inhalation. Use gloves and handle in a well-ventilated fume cupboard.

Toxicity evaluation

All acrylamide in the environment is synthetic, the main source being the release of the monomer residues from polyacrylamide used in water treatment or in industry. Products and compounds containing polyacrylamide can serve as sources of exposure to residues of acrylamide.

Incompatibilities

Acrylamide may decompose with heat and polymerize at temperatures above 84 C, or exposure to light, releasing ammonia gas. Reacts violently with strong oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Reacts with reducing agents; peroxides, acids, bases, and vinyl polymerization initiators. Fine particles of dust form explosive mixture with air.

Toxics Screening Level

The current ITSL for acrylamide (6 μg/m3) has a justification (attached) dated May 8, 2013. The averaging time (AT) assigned at that time was 24 hours, as per the default methodology.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Acrylamide residue and sorbent material may be packaged in epoxy-lined drums and taken to an EPAapproved disposal site. Incineration with provisions for scrubbing of nitrogen oxides from flue gases. Deep well injection.