JPS6220177B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel hydroxy dibasic acid salt compound having a cyclohexane ring and a rust preventive agent comprising the same. (In the formula, n and n' are numbers from 4 to 10, Z is a hydrogen atom,
or a lower alkyl group or an alkali metal or ammonium ion, at least one of which is an alkali metal or ammonium ion, and COOZ is attached to the 2nd or 3rd position of the cyclohexane ring. ), salts of hydroxy dibasic acids having a cyclohexane ring, such as sodium, potassium, lithium, or ammonium, and rust preventives made from the salts. Although various rust preventive agents have been proposed in the past, there are few that are low in toxicity and can be used over a wide range of applications, and few are known that can simultaneously prevent the rust of many types of metals. For example, this type of rust inhibitor includes oil-soluble ones such as petroleum sulfonates, sorbitan monooleate, metal soaps, etc., and water-soluble ones such as inorganic salts such as chromates, phosphates, and nitrites. Examples of salts, water- and oil-soluble ones include ethanolamine, benzotriazole, alkyl phosphate surfactants, long-chain quaternary ammonium halides, and higher amine salts, but these have low solubility in certain solvents or Also, it is only effective for certain metals,
In addition, substances such as chromate are a source of pollution,
More and more items are becoming unusable. Even if they are mixed together, it is not always possible to obtain a rust preventive agent that combines the advantages of both components; they may not dissolve each other, or the disadvantages of each component may appear, or the sustainability of the effect may be lost. It also reacts like nitrite with lower amines to form carcinogenic nitrosamines. Some of the inventors of the present invention have previously investigated methods for producing hydroxycarboxylic acids and their esters, and as a result of continued research into the applications of these salts, they have found that they are low-toxic, safe, low-foaming, etc. In addition to having the following practical advantages, the present inventors have discovered that it has excellent antirust properties against various metals, and based on this knowledge, the present invention has been completed. The above general formula (1) which is an active ingredient of the rust preventive of the present invention
The salt of a hydroxy dibasic acid having a cyclohexane ring represented by can be produced by neutralizing or saponifying the acid or ester of the following general formula () by a conventional method. Examples of the alkali used for neutralization include sodium hydroxide, potassium hydroxide, lithium hydroxide, and ammonium. general formula (In the formula, n and n' are numbers from 4 to 10, and R and R' each represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. COOZ' is attached to the 2 or 3 position of the cyclohexane ring.) Of course, during the production of the salt of this hydroxy dibasic acid, esterification can be carried out as appropriate to convert the carboxyl group at a desired position into an ester group. Conventionally, derivatives of linear carboxylic acids in which a hydroxyl group is bonded to the carbon chain of a linear carboxylic acid are widely known as hydroxycarboxylic acids or esters thereof. On the other hand, as polycarboxylic acids or their esters having a cyclic structure in the molecule, dicarboxylic acids and tricarboxylic acids and their esters having a cyclohexene ring synthesized from linoleic acid, ricinoleic acid, etc. as starting materials have been reported in recent years. ing. However, a dicarboxylic acid having a cyclohexane ring and a hydroxyl group as represented by the above general formula or an ester thereof has not yet been clarified. Therefore, the present inventors investigated the synthesis of this compound, and found that using a dicarboxylic acid having a cyclohexene ring or its ester, which has already been revealed, as a raw material, it was oxidized by the known hydrogen peroxide or potassium permanganate oxidation method. Dihydroxydicarboxylic acid having a cyclohexane ring and its ester were easily obtained. As is clear from the above general formula, the compound in the present invention has a cyclohexane ring in the center of the molecule,
It has a unique structure in which the hydrogen atom of the methylene group is substituted with a hydroxyl group, carboxyl group, long-chain alkyl group, etc., and because there are two hydroxyl groups and two carboxyl groups as functional groups, it is extremely polar. It is a large compound. The raw material used in the present invention is a fatty acid derivative having a cyclohexene ring and has the structure shown in the following general formula. general formula (In the formula, n and n' are 4 to 10, R and R' each represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
^- COOR' is attached to the 2nd or 3rd position of the cyclohexane ring. ) Fatty acid derivatives with a cyclohexene ring and having the molecular structure shown in this general formula have conventionally been synthesized by Diels-Alder addition of acrylic acid or acrylic acid ester to conjugated octadecadienoic acid or its ester; Derivatives synthesized by this method are also applicable as raw materials for this method. In addition,
In this derivative, n and n' are both preferably 4 to 10, but 4 to 7 are usually used. Further, R and R' of the alkyl group may have the same or different carbon numbers. As shown in the general formula, this fatty acid derivative with a cyclohexene ring exists in two types of isomers due to the difference in the bonding position of COOR bonded to the cyclohexene ring. The isomers may be used alone or as a mixture. The rust preventive agent of the present invention can be applied to various uses by preparing the salt of the hydroxy dibasic acid represented by the general formula () as an aqueous solution, and usually has a corrosion resistance of 0.001 to 3.0.
It is used as an aqueous solution, preferably 0.05 to 1.5% by weight. In the present invention, one or more Z in the compound of the general formula () is an alkali metal or ammonium ion. When the proportion of alkali metal or ammonium ions in Z is decreased and the proportion of alkyl groups and/or chain length is increased, an oil-soluble rust inhibitor with relatively low pH can be obtained. The two positional isomers related to COOZ attached to the cyclohexane ring are thought to have little difference in physical properties due to the slight difference in the middle part of the long-chain compound, and it is difficult to separate them, so they were used as a mixture in this experiment. . It should be noted that the difference in antirust ability between isomers is considered to be common sense and negligible. The rust preventive agent of the present invention has low toxicity and excellent rust preventive effect. In particular, it exhibits an excellent rust-preventing effect on many metals such as soft iron, steel, aluminum, brass, copper, tinplate, and galvanized iron. It goes without saying that the rust preventive agent of the present invention can be used not only alone, but also in combination with other known rust preventive agents as appropriate. Next, the present invention will be explained in more detail based on Examples and Reference Examples. The hydroxycarboxylic acid salts used in the Examples were prepared in accordance with Reference Examples 1 and 2 below, and the test method for rust prevention ability was as explained in Example 2. Reference example 1 Raw materials (n=5, n'=7, R and R'=CH ₃ )
7.55 g was weighed into a 100 ml round bottom flask together with 50 ml of formic acid, and 3 ml of a hydrogen peroxide solution (29.6 w/v%) was added dropwise over 10 minutes while stirring while maintaining the temperature at 24-25°C. After the dropwise addition, stirring was continued for about 30 minutes, and then the reaction temperature was raised to 40°C, and the reaction was carried out for 3.5 hours. After the reaction, the reaction solution was poured into water and the separated reaction product was extracted with ether. The extract was then incubated with alkaline solution (5 g NaOH/70 ml H ₂ O) at 95-100 °C for 2.5
The mixture was refluxed for a period of time to perform saponification. After saponification, the produced ester was decomposed with hydrochloric acid (1:1) and the liberated hydroxy acid was extracted with ether. 7.65 g (yield 99.6%) of this ether extract was obtained, and the analysis results were as follows. Neutralization number: 289.0 (theoretical value 290.3), hydroxyl number: 291.7 (theoretical value 290.3), IR spectrum (cm
^-1 ): 3200-3600 (hydroxyl group), 1720 (carbonyl group), ^1H -NMR spectrum (ppm): 0.89
(terminal methyl group), 1.32 (methylene group), 2.27 (methine or methylene group to which a carboxyl group is bonded), 3.2 to 3.8 (methine group to which a hydroxyl group is bonded). ^13C -NMR spectrum (ppm): 14.2
(terminal methyl group), 23.1-32.7 (methylene group), 34.2
(methine group with a carboxyl group attached), 82.1 (methine group substituted with a hydroxyl group), 175.7~
177.6 (carboxyl group). From the above results, the reaction product has the following structure8
-[2 (or 3)-carboxy-4-hexyl-
It was confirmed that it was 5,6-dihydroxy-1-cyclohexyl]octanoic acid. In addition, 2.50 g of this acid was methyl esterified using a conventional method to produce ester (2.64 g, yield 98.5%).
did. The ester value of this ester was 268.5 (theoretical value 270.7), and the formation of dimethyl ester (the following formula) of the above acid was observed. Furthermore, 2.50 g of the acid obtained earlier was ethyl esterified by a conventional method to obtain the following diethyl ester (2.64 g, yield 99.0%). Reference example 2 Raw materials (n=5, n'=7, R=C ₂ H ₂ , R'=H)
5.60g of and tetrabutylammonium bromide
Dissolve 0.25g in 80ml of methylene chloride and add 0.
While stirring at ℃, add an alkaline solution of potassium permanganate (potassium permanganate 7.0g/20wt).
% caustic soda aqueous solution (200 ml) was added dropwise and reaction (stirring) was carried out for about 7 hours. Next, an excess aqueous sodium hydrogen sulfate solution was added to the reaction mixture, and the mixture was acidified with 6N hydrochloric acid to separate the resulting oil and aqueous solution, and the oil was distilled to remove mixed methylene chloride. This residue was further dissolved in ether, washed with water, and the ether was distilled off to obtain a reaction product (5.70 g, yield 93.4%). The analysis results of this reaction product were as follows. Neutralization number: 133.5 (theoretical value 135.3), hydroxyl number:
272.2 (theoretical value 270.7), and similar results to those of Example 1 were obtained in IR and NMR spectral analysis. Therefore, this reaction product is 8-[2
(or 3)-carboxy-4-hexyl-5,6
-dihydroxy-1-cyclohexyl]ethyl octanoate. Example 1 The acid obtained in Reference Example 1 was added to NaOH solution at 90%
Remains through _CO2 after neutralization for 2.5h at ~95℃
The NaOH was changed to Na ₂ CO ₃ and the water was evaporated. EtOH-MeOH was added to the residue and heated to remove insoluble matter (Na ₂ CO ₃ , HCOONa). This solution was further decolorized with activated carbon and purified by MeOH-Acetone reprecipitation. The obtained Na salt was a white crystal with strong hygroscopicity. The results of various analyzes of Na salt are as follows. Acid saturation of the sample
Na salt, i.e. 8-(2-carboxy-4-pentyl 5,6-dihydroxy-1-cycloxyl)
Formation of disodium nonanoate or disodium 8-(3-carboxy-4-pentyl-5,6-dihydroxy-1-cyclohexyl)nonanoate was observed. IR (cm ^-1 ); 3600 (OH group), 1565 (COONa group) ¹ H-NMR (δ) (in D ₂ O); 1.41 (CH ₃ group),
1.81 ( _CH2 group), 2.69 (COONa bonded
CH), 3.9-4.3 (CH with OH attached) ^13C -NMR (δ) (in _D2O ); 14.4 ( _CH3 group),
22.9-36.2 ( _CH2 , CH group), 38.5 ( _CH2-
COONa), 72.6~78.7 (OH-OH group), 183.5~
184.3 (COONa group) Elemental analysis value (%); C, 58.53 (theoretical value 58.59),
H, 8.61 (same as 8.43), Na, 10.58 (same as 10.68) Example 2 A Test method for rust prevention ability (1) Pour 4 ml of sample aqueous solution into a test tube with a lid (φ10 x 70 mm), and add 5 types of test metal pieces. (3×20×
1 or 1.6 mm metal plate) at the same time.90
Shake at ℃ for 24 hours, air dry after immersion, leave to stand at room temperature (20 to 25℃) and relative humidity 93% for a specified number of days, and visually observe and evaluate changes in the metal piece. The evaluation criteria are as follows.

[Table] No significant change or formation of precipitate
() Put 7g of the sample aqueous solution into the same test tube as in (), and add three types of metal pieces (8 x 40 x 1
mm, steel (B, described later), copper, ammonium)
Each metal piece was immersed and allowed to stand at 30±1°C for 10 days, and the metal pieces were wiped lightly with gauze, washed with water and acetone, dried, and the changes in weight were measured and changes in appearance were visually observed and evaluated. . During the measurement, the lid was lightened to allow oxygen to flow, and evaporated water was replenished midway. Table 1 shows the types of metal test pieces used in these tests. B Using the salt obtained in Example 1 (abbreviated as 2OH2Na), an aqueous solution of a predetermined concentration was prepared, and the antirust ability was measured by measurement method D. The results are shown in Table 2. From the results in this table, it was found that steel was excellent under all conditions, copper was quite good, but brass was slightly inferior, and aluminum showed slight discoloration. Example 3 Prepare an aqueous solution of 2OH2Na with a predetermined concentration and perform the measurement method.
Table 3 shows the results of measuring the rust prevention ability using (ii). From the results in this table, good results were obtained in all cases except for a slight discoloration of copper and a slight increase in the amount of aluminum. Therefore, the rust preventive agent of the present invention exhibits excellent effects on copper iron under all conditions, and generally exhibits excellent effects on brass and aluminum, with the exception of being slightly inferior at high temperatures and under high temperatures. There was found.

【table】

【table】

【table】

Claims (1)

[Claims] 1. General formula (In the formula, n and n' are numbers from 4 to 10, Z represents a hydrogen atom or a lower alkyl group, or an alkali metal or ammonium ion, at least one of Z is an alkali metal or ammonium ion ^{, and} COOZ is a cyclohexane A salt of a hydroxy dibasic acid having a cyclohexane ring (attached to the 2nd or 3rd position of the ring). 2 General formula (In the formula, n and n' are numbers from 4 to 10, Z represents a hydrogen atom, a lower alkyl group, or an alkali metal or ammonium ion, at least one of which is an alkali metal or ammonium ion ^{, and} COOZ is a cyclohexane ring. A rust preventive agent comprising a salt of a hydroxy dibasic acid having a cyclohexane ring represented by (at the 2 or 3 position of).