17-Acrylic acid

Acrylic acid (CH2=CHC02H, melting point 13.5°C, boiling point 141°C, density 1.045, flash point 68°C) and acrylates were once prepared by reaction of acetylene and carbon monoxide with water or an alcohol, with nickel carbonyl as catalyst. 

In the presence of such catalysts as a solution of cuprous and ammonium chlorides, hydrogen cyanide adds to acetylene to give acrylonitrile (CH2=CHCN). However, this process has been replaced by processes involving ammoxidation of propylene. Similarly, the process for the manufacture of acrylic acid has been superseded by processes involving oxidation of propylene (Fig. 1) although, for some countries, acetylene may still be used in acrylate manufacture. 

acrylic acid is made by the oxidation of propylene to acrolein and further oxidation to acrylic acid. 

Another method of acrylic acid production is by the hydrolysis of acrylonitrile  

Acrylic acid was originally produced by reacting ethylene oxide with hydrogen cyanide and later by the carbonylation of acetylene, using a nickel tetracarbonyl catalyst promoted with copper halide. It is now generally produced by the oxida- 

It is conunon practice to use two reactors. The first reactor contains a conventional bismuth phosphomolybdate catalyst and is used to convert propylene to acrolein. The second reactor contains a selective vanadium molybdate catalyst promoted with tungsten, nickel, manganese or copper, to convert acrolein to acrylic acid. Fixed bed tubular reactors ate used in both stages. Typical operating conditions ate shown in Table 4.15. 

Synonyms propanoic acid ethylformic acid ethanecarboxylic acid carboxyethane 

Propionic acid is used in the prodnction of propionates used as mold inhibitors and preservatives for grains and wood chips, in the manufacture of fruit flavors and perfume bases, and as an esterifying agent. 

Colorless oily liquid with pungent odor boils at 14LC (285.8°F) melts at -21°C (-5.8°F) density 0.993 at 20°C (68 F) sol-nble in water and most organic acids. 

Combustible liquid flash point (closed cup) 54.5°C (130°F), (open cup) 58°C (136°F) autoignition temperature 465°C (870°F) vapor forms explosive mixtures in air within the range 2.9-12.1% by volume in air. Reactions with strong oxidizers can become violent, especially at elevated temperatures. 

EPA Designated Toxic Waste, RCRA Waste Number U008 DOT Label Corrosive Material, UN 2218 

Synonyms 2-Propenoic acid acroleic acid ethylenecarboxylic acid vinylformic acid 

Starting material for acrylates and polyacrylates used in plastics, water purification, paper and cloth coatings, and medical and dental materials 

Toxicology. Acrylic acid is a severe irritant of the eyes, nose, and skin. The major route of absorption is ingestion of inhaled vapors. 

Medical reports of acute human exposures (concentration unspecified) include moderate and severe skin burns, moderate eye burns and mild inhalation effects. Although acrylic acid is acutely irritating at sites of initial contact, it causes little systemic toxicity. The low systemic toxicity of acrylic acid is likely a consequence of its rapid and extensive metabolism to C02.  

There is a great variability in the reported values for the oral LDso in rats, ranging from 350 to 3200mg/kg. The dermal LD50 in rabbits was 750mg/kg.  

During their total synthesis of cyhndramide A [6], a macrocyclic tetramic acid isolated from Halicondria cylindrata, which is cytotoxic to B16 melanoma cells, Hart and Phillips performed a highly diastereoselective Diels-Alder reaction between acryhmide 13 and cyclopentadiene, applying the methodology developed 

The main use of acrolein is to produce acrylic acid and its esters. Acrolein is also an intermediate in the synthesis of pharmaceuticals and herhicides. It may also he used to produce glycerol hy reaction with isopropanol (discussed later in this chapter). 2-Hexanedial, which could he a precursor for adipic acid and hexamethylene-diamine, may he prepared from acrolein Tail to tail dimenization of acrolein using ruthenium catalyst produces trans-2-hexanedial. The trimer, trans-6-hydroxy-5-formyl-2,7-octadienal is coproduced. Acrolein, may also he a precursor for 1,3-propanediol. Hydrolysis of acrolein produces 3-hydroxypropionalde-hyde which could he hydrogenated to 1,3-propanediol.  

The diol could also he produced from ethylene oxide (Chaper 7). 

There are several ways to produce acrylic acid. Currently, the main process is the direct oxidation of acrolein over a combination molybdenum-vanadium oxide catalyst system. In many acrolein processes, acrylic acid is made the main product by adding a second reactor that oxidizes acrolein to the acid. The reactor temperature is approximately 250°C  

Acrylic acid is usually esterified to acrylic esters by adding an esterification reactor. The reaction occurs in the liquid phase over an ion exchange resin catalyst. 

An alternative route to acrylic esters is via a (3-propiolactone intermediate. The lactone is obtained by the reaction of formaldehyde and ketene, a dehydration product of acetic acid  

Very little attention has been given to the production and evaluation of acrylic or methacrylic acid-MA copolymers. Some studies have shown that the acrylic acid-MA pair can be copolymerized to a 1 1 alternating copolymer, under the condition where MA concentration exceeds the acrylic or methacrylic acid concentration in the starting mixtures (see Chapter 10). Radiation-initiated, solid-state copolymerization of eutectic mixtures of acrylic acid with MA have been investigated by examination of phase diagrams, viscosities, and surface tensions of the binary mixtures.Molecular interactions between the two monomers and crystal dislocations accelerate the polymerization rate. The physical and chemical properties of the copolymers have not been explored. 

Data were last reviewed in lARC (1979) and the compound was classified in lARC Monographs Supplement 7 (1987). 

Services Reg. No.. 79-10-7 Systematic name. 2-Propenoic acid 

2 Structural and molecular formula and relative molecular mass 

Acrylic acid is used primarily as an intermediate in the production of acrylates, which, in turn, are used in the production of polymers for coatings, paints, adhesives, paper and textiles. Exposure to unreacted acrylic acid may occur among consumers. The present recommendation by the American Conference of Governmental Industrial Hygienists (ACGIH) for the threshold limit value (TLV) is 5.9 mg/m in workplace air. The previous TLV, before 1990, was 30 mg/m  

Other Data Relevant to an Evaluation of Carcinogenicity and its Mechanisms 

Checked by Arthuk C. Cope, William R. Armserong, and James J, Ryan. 

The furnace is heated to 590° (Note 4), and after the air has been displaced 200 g. (216 ml., 2 moles) of ethyl acrylate (Note 5) is placed in the separatory funnel and admitted to the reaction tube at a rate of about 90 drops a minute (Note 3), so that the addition requires about 2 hours. At the end of the addition the contents of the receiver and the small amount of liquid in the traps are combined. The total weight of crude acrylic acid containing some ethyl acrylate is 126-136 g. 

If the acrylic acid is not to be used at once, it is stabilized by the addition of hydroquinone and is stored in a refrigerator. 

The middle third of the Pyrex tube should be packed with 20-mm. lengths of fire-polished 7-mm. Pyrex tubing. The lower end of the tube is drawn out to a size that permits attachment to the receiver with a rubber stopper. 

A type FD303 combustion furnace (made and sold by the Hoskins Manufacturing Company, Detroit, Michigan) or any similar furnace is satisfactory. 

---

The oleic acid series, C H2n-202 with one double bond, of which acrylic acid is the lowest member. 

CHi=CMeCOOH. Colourless prisms m.p. 15-16 C, b.p. 160-5 C. Manufactured by treating propanone cyanohydrin with dilute sulphuric acid. Polymerizes when distilled or when heated with hydrochloric acid under pressure, see acrylic acid polymers. Used in the preparation of synthetic acrylate resins the methyl and ethyl esters form important glass-like polymers. 

CHjlCH COOH. Colourless liquid having an odour resembling that of ethanoic acid m.p. 13 C, b.p. I4I°C. Prepared by oxidizing propenal with moist AgO or treating -hy-droxypropionitrile with sulphuric acid. Slowly converted to a resin at ordinary temperatures. Important glass-like resins are now manufactured from methyl acrylate, see acrylic resins. Propenoic acid itself can also be polymerized to important polymers - see acrylic acid polymers. 

Acrylic acid derivatives. Acrylic esters polymerise readily under the influence of oxygen, peroxides, light or heat to give colourless, glass-Uke plastics. 

Apart from the thoroughly studied aqueous Diels-Alder reaction, a limited number of other transformations have been reported to benefit considerably from the use of water. These include the aldol condensation , the benzoin condensation , the Baylis-Hillman reaction (tertiary-amine catalysed coupling of aldehydes with acrylic acid derivatives) and pericyclic reactions like the 1,3-dipolar cycloaddition and the Qaisen rearrangement (see below). These reactions have one thing in common a negative volume of activation. This observation has tempted many authors to propose hydrophobic effects as primary cause of ftie observed rate enhancements. 

Asymmetric hydrogenation has been achieved with dissolved Wilkinson type catalysts (A. J. Birch, 1976 D. Valentine, Jr., 1978 H.B. Kagan, 1978). The (R)- and (S)-[l,l -binaph-thalene]-2,2 -diylblsCdiphenylphosphine] (= binap ) complexes of ruthenium (A. Miyashita, 1980) and rhodium (A. Miyashita, 1984 R. Noyori, 1987) have been prepared as pure atrop-isomers and used for the stereoselective Noyori hydrogenation of a-(acylamino) acrylic acids and, more significantly, -keto carboxylic esters. In the latter reaction enantiomeric excesses of more than 99% are often achieved (see also M. Nakatsuka, 1990, p. 5586). 

The key step in the total synthesis of rhizobitoxine is the Pd-catalyzed exchange reaction of the methyl alkenyl ether moiety in 4 with the functionalized alcohol, although the yield is low[3]. The enol pyruvate 6 (a-ethoxyacrylic acid) is prepared by the reaction of methyl a-methoxyacrylate or a-methoxy-acrylic acid (5) with ethanol catalyzed by PdCl2(PhCN)2 at room temperature in the presence of CuCli and NaH2P04[4],... 

As an application of this nucleophilic reactivity, 2-aminothiazole was used to partially convert into amide the polymer obtained from acrylic acid, benzene, and acetic anhydride (271). An aqueous medium is reported to favor the reaction between acetic anhydride and 2-aminothiazole (272). 

Since the exocyclic sulfur is more reactive in the ambident anion than in A-4-thiazoIine-2-thione. greater nucleophilic reactivity is to be expected. Thus a large variety of thioethers were prepared in good yields starting from alkylhalides (e.g.. Scheme 38 (54, 91, 111, 166-179). lactones (54, 160), aryl halides (54, 152. 180, 181), acyl chlorides (54. 149, 182-184). halothiazoles (54, 185-190), a-haloesters (149. 152. 177. 191-194), cyanuric chloride (151). fV.N-dimethylthiocarbamoyl chloride (151, 152. 195. 196), /3-chloroethyl ester of acrylic acid (197), (3-dimethylaminoethyl chloride (152). l,4-dichloro-2-butyne (152), 1,4-dichloro-2-butene (152), and 2-chloro-propionitrile (152). A general... 

Polylacrylic Acid) and Poly(methacrylic Acid). Glacial acrylic acid and glacial meth-acrylic acid can be polymerized to produce water-soluble polymers having the following structures ... 

Copolymers can be used to introduce a mixture of chemical functionalities into a polymer. Acidic and basic substituents can be introduced, for example, through comonomers like acrylic acid and vinyl pyridine. The resulting copolymers show interesting amphoteric behavior, reversing their charge in solution with changes of pH. 

Acrylic acid polymers Acrylic adhesives Acrylic anhydride Acrylic copolymer Acrylic-cotton blends Acrylic elastomers... 

---