Big encyclopedia of oil and gas. Physical and chemical properties of adipic acid

federal agency of Education

State educational institution higher professional education

Samara State Technical University

Department: « Organic chemistry»

“SYNTHESIS OF ADIPIC ACID”

Course work

Completed:

Supervisor:

Samara, 2007

1. Introduction

1.1. Properties of adipic acid

1.2. The use of adipic acid

1.3. Synthesis of adipic acid

2. Literature review. Methods for obtaining dicarboxylic and polycarboxylic acids

2.2. Condensation reactions

2.3. Michael reactions

2.4. Oxidative Methods

3. Experimental technique

Bibliography

1. Introduction

1.1. Properties adipic acid

Adipic acid (1,4-butanedicarboxylic acid) HOOC (CH 2) 4 COOH, molecular mass 146.14; colorless crystals; m.p. 153°C, b.p. 265°C/100 mmHg Art.; easily sublimes; d 4 18 = 1.344; decomposition point 210-240°C; () = 4.54 (160°С), 2.64 (193°С); ; , , . Solubility in water (g per 100 g): 1.44 (15°C), 5.12 (40°C), 34.1 (70°C). Solubility in ethanol, in ether - limited.

Adipic acid has all the chemical properties characteristic of carboxylic acids. Forms salts, most of which are soluble in water. Easily esterified to mono- and diesters. Forms polyesters with glycols. Salts and esters of adipic acid are called adipinates. When interacting with NH 3 and amines, adipic acid gives ammonium salts, which, upon dehydration, turn into adipamides. With diamines, adipic acid forms polyamides, with NH 3 in the presence of a catalyst at 300-400 ° C - adipodinitrile.

When adipic acid is heated with acetic anhydride, a linear polyanhydride is formed BUT [-CO (CH 2) 4 COO-] n H, during the distillation of which at 210°C an unstable cyclic anhydride (formula I) is obtained, which at 100°C again turns into a polymer. Above 225 °C, adipic acid cyclizes to cyclopentanone (II), which is more easily obtained by pyrolysis of calcium adipate.

In industry, adipic acid is obtained mainly by a two-stage oxidation of cyclohexane. At the first stage (liquid-phase oxidation with air at 142-145°C and 0.7 MPa), a mixture of cyclohexanone and cyclohexanol is obtained, separated by distillation. Cyclohexanone is used to produce caprolactam. Cyclohexanol is oxidized with 40-60% HNO 3 at 55°C (NH 4 VO 3 catalyst); the yield of adipic acid is 95%.

Adipic acid can also be obtained:

a) oxidation of cyclohexane with 50-70% HNO 3 at 100-200°C and 0.2-1.96 MPa or N 2 O 4 at 50°C;

b) oxidation of cyclohexene with ozone or HNO 3 ;

c) from THF according to the scheme:

d) carbonylation of THF to adipic anhydride, from which the acid is obtained by the action of H 2 O.

1.2. Application adipic acid

The main area of ​​application of adipic acid is the production of polyamide resins and polyamide fibers, and these markets have long been formed and are experiencing fierce competition from polyester and polypropylene.

The use of adipic acid in the production of polyurethanes is increasing. Now the growth rate of production and consumption of polyurethanes exceeds the growth rate of production and consumption of polyamides, especially polyamide fibers. For example, the demand for adipic acid from Western European polyurethane producers is constantly increasing, and today its growth rate is approximately 12-15% per year. However, demand for polyamide (nylon) for plastics is also on the rise, especially in the Asian region. This is explained by the fact that for the production of polyurethanes in the Asia-Pacific countries, polyethers are more often used, in the synthesis of which adipic acid does not take part, therefore up to 85% of adipic acid is used here in the production of polyamides. This feature has a ripple effect on the demand for adipic acid in the region, so the average annual growth rate of global demand for this product is projected at 3-3.5%. In Russia own production adipic acid is not yet available, although there are very favorable conditions for this: developed raw material base(cyclohexanol, cyclohexanone, nitric acid), there are large consumers of end products (plasticizers, monomers). The prospective need for adipic acid for Russia is estimated at several tens of thousands of tons per year. AT Russian Federation adipic acid is used for the production of plasticizers, polyamides, pharmaceuticals, polyurethanes.

So, adipic acid is a strategically and economically important raw material in the production of polyhexamethylene adipamide (~ 90% of the acid produced), its esters, polyurethanes; food supplement (gives sour taste especially in the production of non-alcoholic beverages). That is, products based on adipic acid are wide application in the production of polyamides, plasticizers, polyesters, polyester resins for PU, polyurethane foam, in industrial processing glass, in the radio-electronic and electrical industries, in the production of disinfectants, in the food and chemical-pharmaceutical industries, in the production of varnishes and enamels, solvents, self-curing compositions.

1.3. Synthesis adipic acid

Into a 5 liter round bottom flask equipped with a mechanical stirrer, thermometer and separating funnel ca. In 1 liter, place 2100 g (16.6 mol) of 50% nitric acid ( specific gravity 1.32; in a fume hood). The acid is heated almost to boiling and 1 g of ammonium vanadate is added. Start the stirrer and slowly add 500 g (5 mol) of cyclohexanol through a separating funnel. First, 40-50 drops of cyclohexanol are added and the reaction mixture is stirred until the reaction starts (4-5 min), which becomes noticeable by the evolution of nitrogen oxides (Note 3). Then the reaction flask is placed in an ice bath, the contents of the flask are cooled until the temperature of the mixture reaches 55-60 0 C. After that, cyclohexanol is added as soon as possible, maintaining the temperature within the limits indicated above. Toward the end of the oxidation (after 475 g of cyclohexanol had been added), the ice bath was removed; sometimes the flask even has to be heated in order to maintain the required temperature and to avoid cyclization of the adipic acid.

Stirring is continued for another hour after the addition of the entire amount of cyclohexanol. The mixture is then cooled to 0, the adipic acid is filtered off with suction, washed with 500 ml of ice water and air dried overnight. The output of white crystals with so pl. 146-149 0 is 395-410g. By evaporation of the mother liquors, another 30-40 g of product with m.p. 141-144 0 С (note 4). Total yield of crude adipic acid: 415-440g, or 58-60% theoretical. (note 6). The resulting product is reasonably pure for most purposes; however, a purer product can be obtained by recrystallization of crude adipic acid from 700 ml of concentrated nitric acid sp. weight 1.42. cleaning losses are about 5%. Recrystallized adipic acid melts at 151-152 0 (Notes 6 and 7).

Notes.

1. It is suggested not to use a catalyst if the temperature of the reaction mixture, after the start of the reaction, is maintained at 85-90 0 (Hartman, private communication).

2. Used technical cyclohexanol, practically free of phenol. More than 90% of the product boiled within 158-163 0 .

3. It is very important that the oxidation begin before a significant amount of cyclohexanol is added, otherwise the reaction may become violent. The reaction must be carried out in a well-functioning fume hood.

4. Nitric acid mother liquors contain significant amounts of adipic acid mixed with glutaric and succinic acids. It turned out that the separation of these acids by crystallization is practically impractical. However, if nitric acid is removed by evaporation, and the remaining mixture of acids is esterified with ethyl alcohol, then a mixture of ethyl esters of succinic (bp. 121-126 0 /20mm), glutaric (bp. 133-138 0 /20mm) and adipic b.p. (142-147 0 /20mm) acids. These esters can be successfully separated by distillation.

5. The following modified recipe may give a better outcome. In a 3-liter flask equipped with a stirrer, a reflux condenser and a dropping funnel, fixed in asbestos stoppers impregnated with liquid glass, place 1900 ml of 50% nitric acid (1262 ml of nitric acid, sp. weight 1.42, diluted to 1900 ml) and 1 g of vanadate ammonium. The flask is placed in a water bath heated to 50-60 0 , and very slowly, with the stirrer running, 357 g (3.5 mol.) of technical cyclohexanol are added so that the bath temperature is maintained at 50-60 0 . This operation lasts 6-8 hours. The reaction is terminated by heating the water bath to boiling until the evolution of nitrogen oxides ceases (about 1 hour). The hot reaction mixture is siphoned off and allowed to cool. Yield of crude adipic acid: 372g (72% theoretical).

Asbestos plugs impregnated with liquid glass are prepared from a thin asbestos sheet cut into strips 2.5 cm wide. The strips are moistened with a solution of liquid glass and then wound, for example, on the stock of a refrigerator until a cork of the desired size is obtained. After assembling the device, the corks are covered with liquid glass and left to harden overnight.

6. Nitric acid mother liquors after crystallization can replace part of the fresh acid in subsequent oxidation operations.

7. Adipic acid can also be recrystallized from 2.5 times (by weight) water or 50% alcohol. However, these solvents give less satisfactory results than nitric acid.

Other methods of obtaining.

Adipic acid can also be obtained by the oxidation of cyclohexane and cyclohexanone with nitric acid or potassium permanganate. The described method is based on the patents of DeutscheHydrierwerkeA.-G.

Other methods of preparation consist in the oxidation of cyclohexene with potassium dichromate and sulfuric acid and in the interaction of γ-bromobutyric ester with sodium malonic ester, followed by saponification and decarboxylation of the resulting triethyl ester of 1,4,4-butanetricarboxylic acid.

2. Literature review. Methods for obtaining dicarboxylic and polycarboxylic acids

2.1. Carboxylation and alkoxycarbonylation

The carboxyl group can be introduced in two ways. The first way is to use carbon monoxide in the presence of a catalyst, most often an organometallic compound. The second route uses the reaction of the carbanion with carbon dioxide. We will consider both of these methods separately.

(1) Carboxylation with carbon monoxide

A review is devoted to this important method for the preparation of dicarboxylic acids. A typical example is the synthesis of maleic anhydrides by the reaction of acetylene with iron carbonyl in aqueous alkali (scheme (1)). The reaction product (1) when oxidized with potassium ferricyanide or nitric acid gives maleic anhydride. Alkoxycarbonylation of organic halides (RHal) with nickel carbonyl and alkali metal alkoxide was developed by Corey et al. and is used for the synthesis of dicarboxylic acid esters (Scheme (2)).

Mononitriles are obtained by modification of this method (scheme (3)). Apparently, there are no restrictions on the use of this reaction for the synthesis of dinitriles, although no such examples are presented in the original work. Maleimides can be obtained in high yield from the reaction of diphenylacetylene, carbon monoxide, and an aromatic nitro compound using hexadecacarbonylhexarodium (Rh 6 (CO)i 6 ) as a catalyst and a tertiary amine (pyridine, N-methylpyrrolidine) as a solvent (Scheme (4)). Carbon monoxide appears to act in these reactions as a reducing agent and as a carbonylating agent; the reaction mechanism is complex.

Aliphatic α,β- and β,γ-unsaturated acid amides are reacted with carbon monoxide in the presence of a suitable cobalt catalyst to form succinic or glutaric acid imides. Co 2 (CO) 8 is the best catalyst here, although both Raney cobalt and cobalt(II) acetate also catalyze this reaction. N-Substituted Acrylamides. the corresponding succinimides are obtained in high yield (scheme (5)). Similarly, other acrylamide derivatives can be used.

(2) Carboxylation with carbon dioxide

metal transformation organic compounds in a salt of carboxylic acids upon interaction with carbon dioxide - a well-known reaction , with the help of which (scheme (6)) it is possible to carry out both mono- and dicarboxylation. The formation of the dicarboxylic acid depends on the direction of the reaction of the initially formed sodium salt of phenylacetic acid with a local excess of benzyl sodium, which leads to the disodium derivative of phenylacetic acid.

A review is devoted to the preparation of sodium and potassium compounds, which also describes the details of typical experimental procedures. These organometallic compounds can be obtained either by the direct reaction of available organic compounds (usually halide) with alkali metal, or the transmetalation reaction, which is basically an acid-base reaction, both methods are shown using the example of obtaining phenyl sodium (schemes (7) and (8)).

Metallation reactions involving organolithium compounds are also discussed in the review. To obtain dicarboxylic acids, it is necessary to use organobismetallic compounds or organometallic reagents that already contain a carboxyl group. Despite the possibility of side reactions, these transformations are applicable to a variety of compounds. In the following, we consider the most important examples of this reaction.

When treated with Grignard reagents, some allenes carboxylic acids can be converted into organometallic compounds. The subsequent reaction of these compounds with carbon dioxide (scheme (9)) leads to (1-alkylvinyl)malonic acids in good yield.

Alkylmalonic acids are obtained in good yield (scheme (10)) by reacting an aluminum-lithium derivative of a carboxylic acid (2) with carbon dioxide; in turn, the organometallic derivative (2) used in this reaction is obtained by hydroalumination of alkynes-1. For example, when interacting with 2 mol of diisobutylaluminum hydride, hexine-1 leads (in 85% yield) to the organometallic derivative (3) (scheme (11)), which, after treatment with methyllithium, gives (4). This compound reacts with carbon dioxide to form malonic acid, and, as shown in scheme (10), the reaction proceeds through the formation of intermediate (2).

Similarly, it is possible to carry out the conversion of acetylenes to malonic acids using gem-organoboron compounds of type (5) (scheme (12)); when using 2 mol of butyl lithium, a yield of 65-70% can be achieved. Another good method synthesis of derivatives of substituted malonic acid reaction of α-anions of esters with carbon dioxide. Anions are generated using diisopropylamidalithium in tetrahydrofuran,

and the further procedure is reduced to passing carbon dioxide into the anion solution. Subsequent processing leads to an almost pure product (scheme (13)). Excellent results have been obtained with hindered esters such as ethyl 2-methyl propionate; in this case no adverse reactions were observed. good example this reaction is the synthesis of adamantane-2,2-dicarboxylic acid. The method can also be used in the homocuban series; ester (6) can be converted to the corresponding malonic acid derivative (scheme (14)) without degradation or rearrangement of the "cellular" framework.

Using the path shown in scheme (15), a set of dicarboxylic acids can be obtained from butadiene. Under the action of sodium under strictly defined conditions, butadiene dimerizes with the formation of disodium octadiene. The resulting delocalized dianion reacts with carbon dioxide to give a mixture of three possible regioisomeric diene dicarboxylic acids, the hydrogenation of which results in sebacic, 2-ethyl-probic, and 2,5-diethyladipic acids in a ratio of 3.5:5:1, respectively. This important reaction, extended to aromatic compounds such as styrene and 2-methylstyrene, leads to adipic acid derivatives (Scheme (16)), both products being hydrogenated to the corresponding dicyclohexyl derivatives.

The dianion of cyclooctatetraene reacts with carbon dioxide to form a dicarboxylic acid, but the structure (7) previously proposed for this product is incorrect. Alternative formula (8) is consistent with the results on the electrocyclic ring opening of the precursor having trance- stereochemistry, in accordance with the Woodward-Hoffmann rule on the conservation of orbital symmetry (scheme (17)).

An effective reagent for introducing a carboxyl or alkoxycarbonyl group into various carbanions is methylmethoxymagnesium carbonate (MMC) (9). Usually, ketones are converted to esters of a-keto acids, however, the use of an excess of MMA can lead to the inclusion of two methoxycarbonyl groups, as, for example, in the preparation of a synthetically important diester (10) (Scheme (18)).

2.2. Condensation reactions

Most of the general approaches to the synthesis of di- and polycarboxylic acids use condensation reactions. These reactions include Claisen ester condensation and various reactions of malonic and oxalic acid derivatives.

Derivatives of dicarboxylic acids with long chain obtained from the available derivatives of dicarboxylic acids as a result of Claisen ester condensation. One can use, for example, N,N-dimethylsebacamate (11) (Scheme (19)), since only the ester and the adjacent α-methylene group are involved in the condensation.

Alkylation of anions obtained from esters of malonic acid or ethyl cyanoacetate is widely used for the synthesis of monocarboxylic acids, and, as can be seen from scheme (20), can also be used to obtain dicarboxylic acids. When using the corresponding esters of halogen acids as alkylating agents (Scheme (20)) this method can, in principle, make it possible to obtain various di- and polycarboxylic acids.

Another use of diethyl malonate is more specific, since the reaction of diethyl sodium malonate with appropriately protected ethyl glycidates leads to α,β-diethoxycarbonylbutyrolactones, which, upon subsequent hydrolysis, are converted to paraconic acids (12) (scheme (21)). Treatment of paraconic acids with polyphosphoric acid gives the corresponding cyclolenten-2-ones-1, including dihydrojasmone,

Dehydrobenzenes react with malonic esters to give derivatives of homophthalic acid. For example, the reaction of diethyl malonate with about-bromoanisole in tetrahydrofuran in the presence of sodium amide gives 3-methoxyhomophthalimide in 60% yield; when the reaction conditions change, other products may appear. When using bromobenzene as a source of dehydrobenzene and hexamethanol as a solvent, the main reaction products are diethylphenylmalonate (20%), monoethylhomophthalate (10%), and homophthalimide (50%). The mechanism of formation of these products is shown in scheme (22).

For the synthesis of substituted malonic esters, direct alkylation of diethyl sodium malonate can be used, but the method is not entirely successful, as it often leads to by-products resulting from the dehydrohalogenation of alkyl halides. The elimination reaction can be avoided to some extent by using the conjugate addition of the Grignard reagent to the alkylidenemalonate, as in the synthesis tert-butylmalonate by addition of methylmagnesium iodide to isopropylidenemalonate (scheme (23)). The conjugate addition of Grignard reagents to α,β-unsaturated esters serves as the main reaction; it can be greatly accelerated in the presence of 1% (mol.) copper chloride (1). In particular, such organocopper reagents as LiMeCu and MeCuP (C 4 H 9 - n), selectively add to the β-carbon atom of α,β-unsaturated ketones, providing a potential extension of the method by reactions similar to those shown in scheme (23).

Alkylation of esters of β-keto acids can also be used to obtain derivatives of dicarboxylic acids (schemes (24) and (25)). In the general case, the products of these reactions undergo further transformations or, as shown in scheme (24), are used to obtain keto acids.

To obtain derivatives of esters of malonic acid, diethyl oxal can be used by carrying out Claisen ester condensation and subsequent thermal decarbonylation (scheme (26)). This is a fairly general method for introducing an ethoxycarbonyl group. The use of esters, such as diethyl succinate (Scheme (27)), can lead to the production of α-oxo derivatives of dicarboxylic acids by hydrolysis of the β-oxo polycarboxylic acid ester intermediate.

Alkyl derivatives of succinic acid can be obtained by alkylation of the dianion, in turn obtained from monoethylsuccinate; alkylation proceeds regiospecifically (scheme (28)) at the carbon atom adjacent to the ester group. Other a-alkyl derivatives of adipic and pimelic acids can be obtained by a more complex sequence of reactions (Scheme (29)), since in this case the anions easily enter Dieckmann's cyclization.

Reactions similar to scheme (28) can be used to synthesize esters of unsaturated dicarboxylic acids. For example, as a result of the reaction of a monolithium derivative of di- tert-butylglutarate with various ketones, esters of hydroxydicarboxylic acids are obtained in excellent yields (13).

Hydrolysis of esters (13) with simultaneous dehydration leads to unsaturated derivatives of glutaric acid, if substituents R 1 or R 2 are not aromatic in nature (scheme (30)). However, if one of these substituents is aromatic, then hydrolysis is accompanied not only by dehydration, but also by decarboxylation and leads to unsaturated monocarboxylic acids.

The Wittig reaction is the most important general method for the regiospecific synthesis of esters of α,β-unsaturated and polyene dicarboxylic acids. In a typical synthesis (scheme (31)) , as in many similar cases, the reaction product is a mixture cis- and trance-isomers, which in this particular case can be separated by fractional crystallization. The Wittig reaction is especially widely used in the synthesis of carotenoids; in some cases, derivatives of unsaturated dicarboxylic acids are used in these syntheses. As a typical example, we present the synthesis of natural bixin (Scheme (32)): the key intermediate 5-methoxycarbonyl-3-methylpenta- cis-2-grans-4-dienal (14), as shown in the diagram, condenses with ylide (15) to form standard conditions Wittig reactions.

2.3. Michael reactions

The Michael reaction is used to prepare various di- and polycarboxylic acids. In this section, we will look at some typical examples of this reaction. The malonate anion adds to the esters and nitriles of α,β-unsaturated acids to form products that give glutaric acid derivatives upon hydrolysis (schemes (33)-(36)).

Glutaric acids can also be obtained by adding dianions of carboxylic acids to α,β-unsaturated esters (scheme (37)). The isobutyric acid dianion is prepared in tetrahydrofuran at 0° C. using two equivalents of base; the Michael addition is followed by trimethylsilylation of the product.

The complete synthesis of the (±)-avenaciolide fungicide included, as a key step, the preparation of a substituted bislactone (16) as a result of a process similar to the Michael reaction (Scheme (38)). At the last stages of this synthesis, the required double bond was introduced by pyrolysis of sulfoxide in the presence of succinic anhydride.

2.4. Oxidative Methods

Many important pathways leading to di- and polycarboxylic acids include oxidation; some methods found practical use. For convenience, we consider separately the oxidation of aromatic and aliphatic substrates.

(1) Production of aromatic acids

To obtain aromatic di- and polycarboxylic acids, the oxidation of side chains of various aromatic compounds is widely used. Alkylbenzenes, such as isomeric xylenes, readily oxidize to the corresponding carboxylic acids under harsh conditions. The examples in Schemes (39) -(45) illustrate a set of oxidizing agents that can be used for this purpose.

Oxidation of phenanthalene (scheme (46)) serves as a convenient method for the synthesis of both biphenyl-2,2"-dicarboxylic acid and its dimethyl ester. Oxidation of various acyl haloacenaphthenes leads to the corresponding naphthalene α and hydrides, although there are noticeable differences in the ease of formation of anhydrides (scheme (47 )).

(2) Production of aliphatic acids

In the synthesis of dicarboxylic acids in this way, two oxidative processes can be distinguished: the first includes oxidative dimerization, the second involves the cleavage of a carbon-carbon bond, often in cyclic compounds (scheme (47)). Esters of succinic acid can be obtained by oxidative dimerization of enolate anions in the presence of copper (II) salts. The method using lithium enolates (scheme (48)) is simpler and, apparently, is more general character than the alternative method using organozinc compounds (scheme (49)). Both reactions resemble long-known methods of dimerization of stable anions, for example, diethyl malonate anions using iodine as an oxidizing agent (Scheme (50)).

Acetylene acids and their esters undergo oxidative dimerization in high yield in aqueous ethanol under the action of oxygen or air in the presence of ammonium chloride or copper. This reaction was used in the synthesis of corticrocin, the reaction, which proceeded in this case with an almost quantitative yield at room temperature, was carried out by oxygen uptake (scheme (51)).

Olefins can be oxidized to dicarboxylic acids (scheme (52)) different ways, and if there were no problems associated with solubility in organic solvents, potassium permanganate would be most convenient for this purpose. These difficulties can be overcome to some extent if acetic anhydride is used as a solvent. However, in this case, the yields are reduced, and as shown in the example of oxidation according to scheme (53), side reactions can occur.

The use of crown ethers eliminates most of the problems, because these compounds are able to form complexes with metal salts, which leads to an increase in solubility in an organic medium and an increase in the reactivity of anions. For example, dpcn;slohexyl-18-crown-6 forms a benzene-soluble complex (17) with potassium permanganate, which provides an excellent oxidizing agent for organic substrates. In particular, it oxidizes cyclohexene in quantitative yield to adipic acid (scheme (54)). Apparently, there is no reason to assume that the mechanism of this oxidation differs from that acting in aquatic environments(schemes (55), (56)).

Phase transfer catalysis can be used to oxidize alkenes with aqueous potassium permanganate. Reactions of Nitrogen dissolved in the organic phase with inorganic spices in the aqueous phase, which are inhibited by HD separation, are often catalyzed by the addition of trace amounts of tetraalkylammonium or tetra-a-kyaphosphonium salts soluble in the organic phase. It is assumed that catalysis is carried out due to the ability of cations soluble in an organic solvent to repeatedly transfer anions into the organic phase in a form suitable for the reaction. This effect is called phase transfer catalysis.

Ozone treatment of olefins is usually carried out in organic solvents, often at low temperatures. The resulting ozonide (18), which is usually too unstable to be safely isolated, can be oxidized to carboxylic acids. In the oxidation of a cyclic olefin, the reaction product is a dicarboxylic acid (Scheme (57)). This two-step process can be simplified, as it has been shown that, in favorable cases, emulsions of cyclic olefins and alkaline hydrogen peroxide react gently with ozone and form α,co-dicarboxylic acids in good yields (scheme (58)).

Other carbocyclic compounds can also be oxidized to dicarboxylic acids. In a suitable solvent, cyclic ketones are oxidized by molecular oxygen to dicarboxylic acids (scheme (59)). It has been shown that many solvents autoxidize under the reaction conditions; however, the use of hexametapol (HMPTA) reduces these side reactions to a minimum and makes it possible to obtain satisfactory product yields. As a rule, the most acidic bond is oxidized C-H ketone with the formation of an unstable intermediate peroxy anion. Complete oxidation, similar to scheme (59), was achieved by the action of nitric acid.

Noteworthy is another technique involving hydr 0 . lysis since it is a general method for the preparation of perfluoroalkanedicarboxylic acids from a,co-bis(methylthio)polyfluoroalkanes. Telomerization of tetrafluoroethylene in the presence of dimethyl disulfide and gregg-butyl peroxide as a catalyst leads to products of type (21) (scheme (65)). As can be seen from the diagram, these products (P= 2-5) are hydrolyzed with sulfuric acid in methanol to methyl esters of fluorinated dicarboxylic acids.

Bibliography

1. Overview of the adipic acid market in the CIS. M., INFOMIN RESECH LLC, 2006, p. 62.

2. Syntheses of organic preparations. Collection 1. M., IL, 1949.

3. General organic chemistry. Carboxylic acids and their derivatives. Volume 4. M., Chemistry, 1983, 729s.

4. Bogoslovsky B.N., Kazakova Z.S. Skeletal catalysts, their properties and applications in organic chemistry. M., Goshimizdat, 1957.

5. Golodnikov G.V. Practical work on organic synthesis. L., Publishing House of Leningrad State University, 1966, 697p.

6. Guben I., Methods of organic chemistry. Volume 2. issue 1. M.-L. Goshimizdat, 1941, 690s

7. Modern methods experiment in organic chemistry. M., Goshimizdat, 1960, 560s.

8. Fizer L., Fizer M. Reagents for organic synthesis. Volume 2. M., Mir, 1970, 390.

9. Cheronis N., Micro- and semi-micro methods of organic chemistry. M., IL, 1960, 574.

10. Yuryev Yu.K. Practical work in organic chemistry. Issue 1 and 2. Ed. 3rd. M., Publishing House of Moscow State University, 1964.

11. Yuryev Yu.K., Levina R.Ya., Shabarov Yu.S. Practical work in organic chemistry. Issue 4. M. From Moscow State University, 1969.

12. Shabarov Yu.S. Organic chemistry: In 2 books. - M.: Chemistry, 1994.- 848 p.

13. Petrov A.A., Balyan H.V., Troshchenko A.T. Organic chemistry. - M .: Higher. school, 1973. - 623 p.

14. Morrison R., Boyd. Organic chemistry. - M.: Mir, 1974. - 1132 p.

15. Terney A. Modern organic chemistry: In 2 volumes - M.: Mir, 1981. - V.1 - 670 p.; T.2 - 615 p.

16. Roberts J., Casserio M. Fundamentals of organic chemistry: In 2 volumes - 2nd ed. -M.: Mir, 1978. - V.1 - 842 s; T.2 - 888 p.

17. V. F. Traven. Organic chemistry. Volume 1. - M .: Akademkniga, 2004, - 708 p.

18. Freidlin G. N., Aliphatic dicarboxylic acids, Moscow, 1978.

Adipic acid (Adipic acid, hexanedioic acid, 1,4-butanedicarboxylic acid) - belongs to the family of dibasic saturated carboxylic acids. It has good solubility in ethanol, and also limited solubility in ether, but hardly soluble in water. However, most of the salts (adipinates) formed by adipic acid are soluble in water. When dehydrated, adipinates are converted to adipamides. Adipic acid has all the chemical properties characteristic of the carboxylic acid family. It reacts with glycols to form polyesters.

Externally, adipic acid is a white or colorless crystalline substance with a density of approximately 1.36 g / cc. The melting point of adipic acid is about 153 °C, the decomposition temperature is about 220 °C (±20 °C), adipic acid boils at 260 °C.

The most common general method for the synthesis of adipic acid in industry is the oxidation of cyclic compounds (cyclohexane)

GOST 10558-80 distinguishes several grades of adipic acid. The table below shows the main characteristics and their compliance with GOST standards.

Guaranteed shelf life of adipic acid is 1 year.

We offer to pay attention to such raw materials for coatings as Adipic acid. This substance produced in full compliance with current standards and is a high-quality component for paints and varnishes.

The main place among the raw materials for coatings is occupied by film-forming substances. They provide the main qualities of the material: its strength, durability, resistance to external influences. Various resins (alkyd, acrylate, epoxy, etc.) and aqueous dispersions of polymers (acrylic, polyurethane) most often act as film-forming agents.

Various pigments are responsible for the final color of the coating. In addition to decorative qualities, pigments can impart light fastness, electrical conductivity, and other properties to the paintwork. beneficial features. Pigments paintwork materials are divided into inorganic (titanium dioxide, zinc oxide, ocher, etc.) and organic (anthraquinone, phthalocyanine, etc.). To reduce the cost of coatings, special additives-fillers are added to the composition. As a rule, these are substances of natural origin, which, if properly formulated, can improve the quality of the coating.

If you want to give the final coating elasticity, plasticizers (phthalates, phosphates) are added to the composition of the coatings. To speed up the drying process, desiccants are added to the paints (true - salts of carboxylic acids and promoters - salts of barium, calcium, etc.).

Federal Agency for Education

State educational institution of higher professional education

Samara State Technical University

Department:"Organic chemistry"

“SYNTHESIS OF ADIPIC ACID”

Course work

Completed:

Supervisor:

Samara, 2007

1. Introduction

1.1. Properties of adipic acid

1.2. The use of adipic acid

1.3. Synthesis of adipic acid

2. Literary review. Methods for obtaining dicarboxylic and polycarboxylic acids

2.1. Carboxylation and alkoxycarbonylation

2.2. Condensation reactions

2.3. Michael reactions

2.4. Oxidative Methods

3. Experimental technique

Bibliography

1. Introduction

1.1. Properties adipic acid

Adipic acid (1,4-butanedicarboxylic acid) HOOC(CH 2) 4 COOH, molecular weight 146.14; colorless crystals; m.p. 153°C, b.p. 265°C/100 mmHg Art.; easily sublimes; d 4 18 = 1.344; decomposition point 210-240°C;

Adipic acid has all the chemical properties characteristic of carboxylic acids. Forms salts, most of which are soluble in water. Easily esterified to mono- and diesters. Forms polyesters with glycols. Salts and esters of adipic acid are called adipinates. When interacting with NH 3 and amines, adipic acid gives ammonium salts, which, upon dehydration, turn into adipamides. With diamines, adipic acid forms polyamides, with NH 3 in the presence of a catalyst at 300-400 ° C - adipodinitrile.

When adipic acid is heated with acetic anhydride, a linear polyanhydride is formed BUT [-CO (CH 2) 4 COO-] n H, during the distillation of which at 210°C an unstable cyclic anhydride (formula I) is obtained, which at 100°C again turns into a polymer. Above 225 °C, adipic acid cyclizes to cyclopentanone (II), which is more easily obtained by pyrolysis of calcium adipate.

In industry, adipic acid is obtained mainly by a two-stage oxidation of cyclohexane. At the first stage (liquid-phase oxidation with air at 142-145°C and 0.7 MPa), a mixture of cyclohexanone and cyclohexanol is obtained, separated by distillation. Cyclohexanone is used to produce caprolactam. Cyclohexanol is oxidized with 40-60% HNO 3 at 55°C (NH 4 VO 3 catalyst); the yield of adipic acid is 95%.

Adipic acid can also be obtained:

a) oxidation of cyclohexane with 50-70% HNO 3 at 100-200°C and 0.2-1.96 MPa or N 2 O 4 at 50°C;

b) oxidation of cyclohexene with ozone or HNO 3 ;

c) from THF according to the scheme:

d) carbonylation of THF to adipic anhydride, from which the acid is obtained by the action of H 2 O.

1.2. Application adipic acid

The main area of ​​application of adipic acid is the production of polyamide resins and polyamide fibers, and these markets have long been formed and are experiencing fierce competition from polyester and polypropylene.

The use of adipic acid in the production of polyurethanes is increasing. Now the growth rate of production and consumption of polyurethanes exceeds the growth rate of production and consumption of polyamides, especially polyamide fibers. For example, the demand for adipic acid from Western European polyurethane producers is constantly increasing, and today its growth rate is approximately 12-15% per year. However, demand for polyamide (nylon) for plastics is also on the rise, especially in the Asian region. This is explained by the fact that for the production of polyurethanes in the Asia-Pacific countries, polyethers are more often used, in the synthesis of which adipic acid does not take part, therefore up to 85% of adipic acid is used here in the production of polyamides. This feature has a ripple effect on the demand for adipic acid in the region, so the average annual growth rate of global demand for this product is projected at 3-3.5%. In Russia, there is no own production of adipic acid, although there are very favorable conditions for this: a developed raw material base (cyclohexanol, cyclohexanone, nitric acid), there are large consumers of end products (plasticizers, monomers). The prospective need for adipic acid for Russia is estimated at several tens of thousands of tons per year. In the Russian Federation, adipic acid is used for the production of plasticizers, polyamides, pharmaceuticals, and polyurethanes.

So, adipic acid is a strategically and economically important raw material in the production of polyhexamethylene adipamide (~ 90% of the acid produced), its esters, polyurethanes; food additive (gives a sour taste, in particular in the production of soft drinks). That is, products based on adipic acid are widely used in the production of polyamides, plasticizers, polyesters, polyester resins for PU, PU foam, in the industrial processing of glass, in the electronic and electrical industries, in the production of disinfectants, in the food and chemical-pharmaceutical industries, in obtaining varnishes and enamels, solvents, self-curing compositions.

1.3. Synthesis adipic acid

Into a 5 liter round bottom flask equipped with a mechanical stirrer, thermometer and separating funnel ca. In 1 l, place 2100 g (16.6 mol) of 50% nitric acid (specific gravity 1.32; in a fume hood). The acid is heated almost to boiling and 1 g of ammonium vanadate is added. Start the stirrer and slowly add 500 g (5 mol) of cyclohexanol through a separating funnel. First, 40-50 drops of cyclohexanol are added and the reaction mixture is stirred until the reaction starts (4-5 min), which becomes noticeable by the evolution of nitrogen oxides (Note 3). Then the reaction flask is placed in an ice bath, the contents of the flask are cooled until the temperature of the mixture reaches 55-60 0 C. After that, cyclohexanol is added as soon as possible, maintaining the temperature within the limits indicated above. Toward the end of the oxidation (after 475 g of cyclohexanol had been added), the ice bath was removed; sometimes the flask even has to be heated in order to maintain the required temperature and to avoid cyclization of the adipic acid.

Stirring is continued for another hour after the addition of the entire amount of cyclohexanol. The mixture is then cooled to 0, the adipic acid is filtered off with suction, washed with 500 ml of ice water and air dried overnight. The output of white crystals with so pl. 146-149 0 is 395-410g. By evaporation of the mother liquors, another 30-40 g of product with m.p. 141-144 0 С (note 4). Total yield of crude adipic acid: 415-440g, or 58-60% theoretical. (note 6). The resulting product is reasonably pure for most purposes; however, a purer product can be obtained by recrystallization of crude adipic acid from 700 ml of concentrated nitric acid sp. weight 1.42. cleaning losses are about 5%. Recrystallized adipic acid melts at 151-152 0 (Notes 6 and 7).

Notes.

1. It is suggested not to use a catalyst if the temperature of the reaction mixture, after the start of the reaction, is maintained at 85-90 0 (Hartman, private communication).

2. Used technical cyclohexanol, practically free of phenol. More than 90% of the product boiled within 158-163 0 .

3. It is very important that the oxidation begin before a significant amount of cyclohexanol is added, otherwise the reaction may become violent. The reaction must be carried out in a well-functioning fume hood.

4. Nitric acid mother liquors contain significant amounts of adipic acid mixed with glutaric and succinic acids. It turned out that the separation of these acids by crystallization is practically impractical. However, if nitric acid is removed by evaporation, and the remaining mixture of acids is esterified with ethyl alcohol, then a mixture of ethyl esters of succinic (bp. 121-126 0 /20mm), glutaric (bp. 133-138 0 /20mm) and adipic b.p. (142-147 0 /20mm) acids. These esters can be successfully separated by distillation.

5. The following modified recipe may give a better outcome. In a 3-liter flask equipped with a stirrer, a reflux condenser and a dropping funnel, fixed in asbestos stoppers impregnated with liquid glass, place 1900 ml of 50% nitric acid (1262 ml of nitric acid, sp. weight 1.42, diluted to 1900 ml) and 1 g of vanadate ammonium. The flask is placed in a water bath heated to 50-60 0 , and very slowly, with the stirrer running, 357 g (3.5 mol.) of technical cyclohexanol are added so that the bath temperature is maintained at 50-60 0 . This operation lasts 6-8 hours. The reaction is terminated by heating the water bath to boiling until the evolution of nitrogen oxides ceases (about 1 hour). The hot reaction mixture is siphoned off and allowed to cool. Yield of crude adipic acid: 372g (72% theoretical).

Adipic acid (there is another name for this substance - 1,4-butanedicarboxylic acid, the systematic name is hexanedioic acid) is a limiting dibasic carboxylic acid. Has the following chemical formula: HOOC(CH2)4COOH and gross formula C6O4H10. It has the same chemical properties as carboxylic acids. Forms salts, many of which are soluble in water (H2O). It is esterified to di- and monoesters. With glycols, hexanedioic acid forms polyesters.

Properties of adipic acid

4. When adipic acid is heated, their amides are formed.

5. Under the influence of SOCl2, adipic acid is converted into the corresponding acid chloride.

Esters of adipic acid

1. Methyl adipate is used for the electrochemical synthesis of dimethyl sebacate.

2. Diallyladipate is a hardener for polyester resins.

3. Ethyl adipate is used as an additive to increase its octane number.

4. Diethyl adipate is used as a plasticizer in the production of food films, shoes, PVC, artificial leather, children's toys, linoleum, stretch ceilings.

5. Diisopropyl adipate is used as an ingredient in skin cosmetics.

Hexanedioic or adipic acid (e355) is a dietary supplement of the antioxidant group.

From a physical point of view, the substance is a colorless crystals. Adipic acid is on the list of additives approved by the European Union, however, on this moment its use is banned in many countries, as the acid is still under testing.

Obtaining adipic acid

Industrially, e355 is obtained mainly by means of a two-stage oxidation of cyclohexane. Initially, a mixture of cyclohexanone and cyclohexanol is obtained, which is then separated by distillation. Cyclohexanone is subsequently used to produce caprolactam, and cyclohexanol is oxidized with 40-60% nitric acid to produce adipic acid. Its yield with this method of obtaining is about 95%.

There is another promising way to obtain adipic acid by hydrocarbonylation of butadiene. Today, about 2.5 million tons of adipic acid are produced worldwide.

The use of adipic acid

On the territory of those states where the food additive e355 is approved for use, it is used as an acidity regulator in the preparation of caramel sweets, drinks and other food products to maintain the required pH level. The additive is added to some types of dry flavored desserts, but in a strictly prescribed amount - up to 1 g / kg of finished products.

In jelly-like desserts, the norm of adipic acid is not more than 6 g / kg, and in powder mixtures for preparing drinks, 4 g / kg is allowed. The e355 additive is often added to fillings for bakery and confectionery products.

Apart from Food Industry Adipic acid is widely used in chemical industry. Thus, about 90% of all acid produced is used as raw material in the production of polyhexamethylene adipamide, as well as its esters and polyurethanes. Acid is used to remove material left after filling the joints between ceramic tiles, as well as in the manufacture of products designed to remove scale.

Impact on the human body

Naturally, in excessively high dosages, any food additives can harm human health. Since the current influence food additive on the human body has not been fully studied, its use is allowed only in a strictly defined concentration.

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