JPH01234403A - Production of imide group-containing vinyl polymer - Google Patents

Abstract

PURPOSE:To efficiently obtain at low cost the title vinyl polymer in compatible with flexible vinyl chloride polymers, useful as a binder resin for toners, by esterification between a carboxyl group-contg, vinyl polymer and an imide group-contg. alcohol. CONSTITUTION:The objective vinyl polymer can be obtained by esterification between a carboxyl group-contg. vinyl polymer and an imide group-contg. alcohol. Said carboxyl group-contg. vinyl polymer is pref. a polymer produced by polymerization e.g., between (meth)-acrylic acid or maleic acid and styrene or diacetone-methacrylamide. Said imide group-contg. alcohol is pref. a compound of formula I [R1 is 1-6C alkylene or divalent organic group having alicyclic or aromatic ring; R2 is of formula II-V (R3 is -CH2-, etc.)].

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an imide group-containing vinyl polymer which is particularly useful as a binder resin for use in toners for developing electrostatic images used in fields such as electrophotography and electrostatic recording. Concerning the manufacturing method of coalescence.

(Prior Art) Toners used in fields such as electrophotography and electrostatic recording include toners using polystyrene (Japanese Patent Publication No. 16118/1982) and toners using styrene-butyl methacrylate copolymer. (Japanese Patent Publication No. 56-11143), etc., in which a vinyl polymer is used as a binder resin is generally used.

Since binder resin makes up the majority of toner components,
It has a large influence on toner performance such as fixing characteristics, durability, and environmental resistance, and it is no exaggeration to say that the performance of the toner is influenced by the type of PAIN DA resin used.

(Problem to be Solved by the Invention) By the way, printed matter output from printers, copiers, facsimile machines, etc. that utilize electrophotography and electrostatic recording is made of soft vinyl chloride polymer in order to prevent stains and damage and preserve it for a long period of time. It is often protected with a sheet consisting of.

However, since toners using the above-mentioned vinyl polymers have the property of being compatible with soft vinyl chloride polymers, when printed matter is brought into contact with soft vinyl chloride polymers, characters and figures are removed from the toner carrier in a very short time. It has the disadvantage that it peels off, impairing the original function of the printed material, which is to retain a visible image.

This is due to the compatibility between the vinyl polymer and the soft vinyl chloride polymer.

In view of the above-mentioned problems, it is an object of the present invention to provide a vinyl polymer that is particularly useful for toner binder resins and has a property of being adhesively incompatible with sheets made of soft vinyl chloride polymers.

(Means for Solving the Problems) The present invention relates to a method for producing an imide group-containing vinyl polymer, which is characterized by carrying out an esterification reaction between a carboxyl group-containing vinyl polymer and an imide group-containing alcohol.

The carboxyl group-containing vinyl polymer used in the present invention is obtained by polymerizing a carboxyl group-containing vinyl monomer or this with another vinyl monomer.

The carboxyl group-containing vinyl monomer is as follows.

Acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, ticric acid. 4-pentenoic acid.

Examples include citraconic acid, mesaconic acid, an acid anhydride having a 9-polymerizable unsaturated group, and a sitting ester compound of a hydroxyl group-containing compound.

Other vinyl monomers that can be copolymerized with the carboxyl group-containing vinyl monomer include styrene, methoxystyrene, butoxystyrene, α-methylstyrene, p-methylstyrene, p-t-butylstyrene, p- Styrene derivatives such as chlorstyrene, ethyl methacrylate, ethyl methacrylate.

Propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, glycidyl methacrylate, methoxyethyl methacrylate, propoxyethyl methacrylate, butoxyethyl methacrylate , methoxydiethylene glycol methacrylate, ethoxydiethylene glycol methacrylate, methoxyethylene glycol methacrylate, butoxytriethylene glycol methacrylate, methoxydipropylene glycol methacrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate, phenoxytetraethylene glycol methacrylate.

Benzyl methacrylate, cyclohexyl methacrylate,
Tetrahydrofurfuryl methacrylate, synclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate, N-vinyl-2-pyrrolidone methacrylate,
Methacrylonitrile.

methacrylamide, N-methylolmethacrylamide,
Ethyl methacrylate morpholine, 2-hydroxyethyl methacrylate, hydroxyglovir methacrylate, hydroxybutyl methacrylate.

2-hydroxy-3-phenyloxypropyl methacrylate, diacetone methacrylamide, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate.

Hexyl acrylate, heptyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, glycidyl acrylate, methoxyethyl acrylate, propoxyethyl acrylate, butoxyethyl acrylate, methoxy acrylate Diethylene glycol, ethoxydiethylene glycol acrylate, methoxyethylene glycol acrylate, butoxytriethylene glycol acrylate,
Acrylic methoxydipropylene glycol.

Phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, acrylic phenoxytetraethylene glycol, benzyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, acrylic IIWN-vinyl 2 -pyrrolidone, hydraxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxy-3-phenyloxypropyl acrylate,
Glycidyl acrylate, acrylonitrile.

Acrylamide, N-methylolacrylamide.

Diacetone acrylamide, diethylaminoethyl methacrylate, ethylmorpholine acrylate.

Vinyl monomers having one vinyl group in each molecule such as vinylpyridine, divinylbenzene, reaction products of glycol and methacrylic acid or acrylic acid2, such as ethylene glycol dimethacrylate, 1,3-butylene dalicol di Methacrylate, 1.4-butanediol dimethacrylate, 1゜5-bentanediol dimethacrylate, 1.6-hexanediol diacrylate, neopentyl glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, Tripropylene/glycol dimethacrylate, hydroxypivalic acid, opentyl glycol ester dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate,
Pen 4 erythritol trimethacrylate, pentaerythritol tetramethacrylate, trisacryloxyethyl phosphate, bis(methacryloyloxyethyl)
hydroxyethyl isocyanurate, tris(methacryloyloxyethyl) inocyanurate, ethylene glycol diacrylate, 1゜3-butylene glycol diacrylate, 1,4-butanediol diacrylate)
, 1.5-pentanediol diacrylate), 1.6-
Hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate Acrylate, pentaerythritol triacrylate, tris(methacryloyloxyethyl)phosphate, bis(methacryloyloxyethyl)hydroxyethyl isocyanurate, tris(methacryloyloxyethyl)in cyanurate.

Half esters of glycidyl methacrylate and methacrylic acid or acrylic acid, half esters of bisphenol-type epoxy resin and methacrylic acid or acrylic acid, half esters of glycidyl acrylate and methacrylic acid or acrylic acid, etc. in one molecule. There are vinyl monomers having two or more vinyl groups.

In the polymerization of these monomers, the polymerization initiators used include 2.2'-azobisisobutyronitrile, 2.2'-azobisisobutyronitrile,
'-azobis-(2,4-dimethylvaleronitrile),
2. Azo compounds such as 2'-azobis-(4-methoxyse-4-dimethylvaleronitrile).

t-butyl peroxy (2-ethylhexanoate),
Peroxy esters such as t-butylperoxyisobutyrate, 1,1-bis(1-butylperoxy)3,3
．． 5-) Limethylcyclohexane.

1. Peroxyketal such as 1-bis(1-butylperoxy)cyclohexane, dicumyl peroxide, 2
．． 5-dimethyl-2,5-di(t-butylperoxy)
There are dialkyl peroxides such as hexane, diacyl peroxides such as benzoyl peroxide, and acetyl peroxide.

These are preferably used in an amount of 0.1 to 15% by weight based on the total vinyl monomer.

The carboxyl group-containing vinyl polymer can be produced by any of solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization.

Among the above polymerization methods, the solution polymerization method and the bulk polymerization method are preferred, and the solution polymerization method is particularly preferred because of its superior uniformity and ease of reaction.

The solvent used in the above solution polymerization is benzene.

Toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate.

One or more known compounds such as ethylene glycol monoethyl ether, ethylene glycol motubutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethanol, propatool, butanol, hexanol, cyclohexanone, aliphatic hydrocarbons, etc. It can be used in It is important to take measures to ensure that the vinyl polymer is sufficiently dissolved during use.

The above solubility depends on the composition of the bipolymer, the molecular weight, the type of functional group,
Although it cannot be limited to a specific solvent since it varies depending on the amount, solvents such as toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexane are particularly preferred. Although the ratio of monomer to solvent is arbitrary, it is preferably 1/3 to 3/1 (weight ratio) from the viewpoint of production efficiency.

In suspension polymerization, polyvinyl alcohol.

Sodium polyacrylate, calcium phosphate.

This is done using a dispersion stabilizer such as calcium carbonate or bentonite. These dispersion stabilizers are dissolved in water to form a dispersion medium. The ratio of dispersion medium to monomer is preferably 1/3 to 3/1.

Polymerization is carried out at a temperature at which a polymer is substantially obtained, that is, at a temperature at which the reaction is completed within several tens of hours.

Polymerization temperature is determined by the type of polymerization initiator used.

In the present invention, "polymerization temperature" is defined as the temperature at which the half-life of the polymerization initiator is less than 40 hours.

For example, as a polymerization initiator, 1.1-bis(t-butylperoxy)&&5-trimethylcyclohexane, 1.1-
Bis(t-butylperoxy)cyclohexane, τ-
Azobisisobutyronitrile.

Benzoyl peroxide, t-butyl peroxide (
When 1fC2τ-azobis(2-ethylhexanoate) etc. are used, the degree of one polymerization is 80°C or higher, and 1fC2τ-azobis(2-ethylhexanoate) is used.
, 4-dimethylvaleronitrile).

When t-butyl peroxyvivalate or the like is used, the temperature is 60°C. However, if polymerization is carried out at the above temperature, a polymer can be obtained in about 20 hours.

In addition, amines and sulfinate salts can be prepared using known methods.

If a polymerization accelerator such as sulfite is used in combination, the polymerization temperature can be lowered by 10°C or more from the above temperature.

What is the carboxyl group content of the vinyl polymer?

Carboxyl value of vinyl polymer 30 (KO) [mg
/g) or more, particularly preferably 60
~600. An imide group-containing vinyl polymer obtained when the carboxyl value is outside the above range.

Adhesion resistance to soft vinyl chloride polymers tends to be insufficient.

Next, examples of the imide group-containing alcohol used in the present invention include those represented by the following general formula.

General formula [However, R in formula 9 represents an alkylene group having 1 to 6 carbon atoms or a divalent organic group having an alicyclic ring or an aromatic ring, R
8 is CH.

CHI CH2-1CHz CH- or -CH=C
(representing H-) or derivatives thereof] Derivatives include one substituent such as an alkyl group, halogen, -N3゜95 (R5, 几, and R3 are hydrogen or an alkyl group), or two or more Fi Examples include those that have.

Specifically, the following may be mentioned.

, II U These imide group-containing alcohols are known and can be made to react, for example, by heating approximately equivalent amounts of an amino group-containing alcohol and a bonic acid in a solvent such as toluene.

These imide group-containing alcohols are used alone or in combination of two or more, and are subjected to an esterification reaction with a carboxyl group-containing vinyl polymer.

What is the esterification reaction of alcohols containing imide groups?

This can be done by a conventional method. During the esterification reaction, it is basic to mix the imide group-containing alcohol's hyporoxyl group and the carboxyl group-containing vinyl polymer's power (phoxyl group) in equal equivalent amounts, but each is blended in nine molecules. In order to leave the carboxyl group, the hydroxyl group may be reacted with a smaller equivalent amount than the carpoloxyl group, so that the imide group obtained by the esterification reaction and the carboxyl group originally present in the 9 molecules coexist. . Therefore, carboxyl group/hydroxyl group H1, O/
It is preferable that the ratio is 1.1 to 1.010.2 (equivalence ratio), and more preferably 1.0/1.0 to 1.010.
．． The range is 5. Outside this range, a large amount of imide group-containing alcohol that does not participate in the reaction may be incorporated into the polymer, or the amount of imide groups produced may be small, resulting in poor adhesion resistance of the toner to the soft vinyl chloride polymer.

This is not preferable because the hygroscopicity and charging properties are likely to be impaired.

For the purpose of promoting the 9 reaction during the esterification reaction, para-toluenesulfonic acid, tetrabutyl titanate, dibutyltin dilaurate, dibutyltin oxide, zinc oxide, etc. are preferably added in an amount of 0.01 to 10% by weight based on the imide group-containing alcohol. can be added in an amount of 1 to 8% by weight.

Further, the reaction temperature is in the range of 80 to 150°C, preferably 100 to 140°C, based on the reaction rate. The esterification reaction can be controlled by monitoring the carboxyl value and is usually completed in 5 to 20 hours.

After the reaction is completed, the imide group-containing vinyl polymer can be obtained by removing the solvent by vacuum drying, dropping into a poor solvent, or the like.

The imide group-containing vinyl polymer obtained by the present invention is
In addition to being useful as a binder resin for toners for developing electrostatic images, it can also be suitably used in solution-type paints, powder paints, etc. that require heat resistance of 9%.

(Example) Examples and comparative examples of the present invention will be described below.

Example 1 First, the following vinyl monomer and polymerization initiator are prepared.

Vinyl monomer Part by weight Methacrylic acid -16,7 styrene
...60.0 Butyl acrylate
...23.3 Polymerization initiator benzoyl peroxide ...2.2 Next, partially saponified polyvinyl alcohol (Tenkapopal W24
．． A reaction vessel containing 100 parts by weight of an aqueous dispersion medium in which 0.3 parts by weight of Denki Kagaku Kogyo (product name) was dissolved was heated to 90±2°C.
After the temperature was raised to , the above-mentioned mixture of vinyl monomer and polymerization initiator was added dropwise over about 2 hours, and the mixture was kept at the same temperature for 7 hours. The mixture was then filtered and dried with hot air to obtain a carboxyl group-containing vinyl polymer having a carboxyl value of 109.

Next, 3 parts by weight of the above-mentioned carboxyl group-containing vinyl N copolymer.

A reaction vessel containing 27 para-toluenesulfone rR1, 4 parts by weight (5% by weight relative to the imide group-containing alcohol) represented by formula A1 and 100 parts by weight of toluene was heated to 12
The temperature was raised to 0° C., and the esterification reaction was promoted while condensed water was distilled out of the system. The same temperature was maintained for 10 hours. The solvent ratio in the esterification reaction was 50 parts by weight, and the carboxyl group/hydroxyl group was 1.0/1.0 (equivalent ratio). Toluene was removed using a vacuum dryer. The imide group-containing vinyl polymer obtained had a carboxyl value of 1 or less and a nonvolatile content of 99% by weight or more.

Next, a toner was produced using this imide group-containing vinyl polymer by the following method, and its performance was investigated.

91 parts by weight of the above imide group-containing vinyl polymer, 5 parts by weight of Carpon Lacuna 44 (manufactured by Mitsubishi Chemical Industries, Ltd.), Oil Black BY (nigrosine dye, manufactured by Orient Chemical Industries, Ltd.)
211Ull, Viscole 550p (Sanyo Chemical Industries ■
2 parts by weight of polypropylene) were premixed using a Henschel mixer and then melt-kneaded using a kneader. Then, it is finely ground with a jet mill.

It was classified to obtain a toner having a particle size of 5 to 25 μm.

Next, the above toner is 3% by weight and the apparent density is 4 to 4.5 g.
/an'', a developer mixed with 97% by weight of an iron oxide powder carrier containing 90% by weight or more of particles with a particle size of 44 to 177 μm was prepared, and a developer was prepared using a magnetic brush method using a laser printer with a drum circumferential speed of about 20an/sec. Reversal development was performed.

The printed matter was good at the initial stage and after printing 200,000 copies, with a print density of 1.1 or more and a capri density of 0.09 or less.

Further, even after the printed matter was adhered to a soft vinyl chloride polymer (dioctyl phthalate content: 25% by weight) and left at a temperature of 40°C and a pressure of 100 gf/an'' for 200 hours, no illegible characters due to print defects occurred. The print density and capri density were measured using a microphotometer model MPM manufactured by Union Optical Co., Ltd.

Example 2 Vinyl monomer Part by weight Methacrylic acid...125 Styrene
...56.3 Dibutyl fumarate ・
...31.2 Polymerization initiator benzoyl peroxide ...3.0 Using the above composition, one polymerization was carried out in the same manner as in Example 1 to obtain a carboxyl group-containing vinyl polymer with a carboxyl value of 82.

Next, 75 parts by weight of the above carboxyl group-containing polymer.

2A! 25 parts by weight of imide group-containing alcohol.

A reaction vessel containing 0.5 parts by weight of paratoluenesulfonic acid (2% by weight relative to the imide group-containing alcohol), 60 parts by weight of xylene, and 10 parts by weight of methyl isobutyl ketone was heated to 140°C, and condensed water was added. The esterification reaction was promoted while distilling it out of the system.

The same temperature was maintained for 15 hours. The solvent ratio in the esterification reaction was 41% by weight, and the carboxyl group/hydroxyl group ratio was 1.0/1.0 (equivalent ratio). The solvent was removed dropwise into methanol to transfer most of the xylene and methyl isobutyl ketone to methanol, followed by filtration to remove the polymer, which was further vacuum-dried. The imide group-containing vinyl polymer obtained had a carboxyl value of 1 or less and a nonvolatile content of 99% by weight or more.

Next, a toner was produced in the same manner as in Example 1, and its performance was examined. As a result, the printed matter had a good print density of 1.1 or more and a capri density of 0.09 or less both at the initial stage and after printing 200,000 copies. Furthermore, no printing damage occurred due to contact with the soft vinyl chloride polymer.

Example 3 Vinyl monomer parts by weight acrylic acid
...7,7 styrene
...62.3 Butyl acrylate
...30.0 Polymerization initiator 1.1-bis(t-butyl ...1.0 peroxy) 3,3.5-trimethylcyclohexane The above composition was polymerized in the same manner as in Example 1, and carboxyl A carboxyl group-containing vinyl polymer having a valence of 60 was obtained.

Next, 78 parts by weight of the above carboxyl group-containing vinyl polymer.

22 parts by weight of imide group-containing alcohol represented by A3.

1.5 parts by weight of para-toluenesulfonic acid (7 parts by weight relative to the alcohol containing imide groups) 40 parts by weight of Chef.

A reaction vessel containing 10 parts by weight of methyl isobutyl ketone was heated to 100° C., and the esterification reaction was promoted while condensed water was distilled out of the system. The same temperature was maintained for 15 hours. The solvent ratio in the esterification reaction was 33% by weight,
The carboxyl group/hydroxyl group ratio is 1.0/1.0 (equivalent ratio). Removal of the solvent was performed in a vacuum dryer. The imide group-containing vinyl polymer obtained had a carboxyl value of 1 or less and a nonvolatile content of 99% by weight or more.

Next, 18 parts by weight of the above imide group-containing vinyl polymer.

73 parts by weight of the imide group-containing vinyl polymer obtained in Example 1, carbon black≠445 parts by weight.

Oil black BY 2 parts by weight, Viscole 550p
A toner was produced in the same manner as in Example 1 using 2 parts by weight, and the toner performance was examined. As a result, the printed matter had a print density of 1.1 or more and a capri density of 0 even after printing 200,000 sheets.
,09 or less, which was good. Furthermore, no printing damage occurred due to contact with the soft vinyl chloride polymer.

Example 4 Vinyl monomer Part by weight Maleic acid
...60 styrene
...20 Butyl acrylate ・
...20 Polymerization initiator benzoyl peroxide ...3 Solvent toluene ...130 Methyl isobutyl keto/ ...20 Contains the above composition,
The temperature of the reaction vessel was raised to 90±2° C., and the reaction was carried out for 10 hours to obtain a carboxyl group-containing vinyl polymer having a carboxyl value of 580.

Next, the above carboxyl group-containing vinyl polymer solution 76.5
Parts by weight (Content of vinyl polymer: 30.6 parts by weight).

69.4 parts by weight of imide group-containing alcohol represented by formula A4.

Toluene 54.1 m, para-toluenesulfonic acid 2
．． 8 parts by weight (4% by weight based on imide group-containing alcohol)
) was heated to 120° C., and the esterification reaction proceeded while distilling condensed water out of the system. The temperature was maintained for 10 hours. Next, vacuum drying is performed to obtain a carboxyl value of 55. An imide group-containing vinyl polymer having a nonvolatile content of 99% by weight or more was obtained. The solvent ratio in the esterification reaction is 50% by weight, and the carboxyl group/hydroxyl group is 1
．． 010.7 (equivalent ratio).

25 parts by weight of the above imide group-containing vinyl polymer having carboxyl groups, 48 parts by weight of the imide group-containing vinyl polymer obtained in Example 1, 18 parts by weight of the imide group-containing vinyl polymer obtained in Example 3 , 445 parts by weight of carbon blackna, 2 parts by weight of oil black BY, 55 parts by weight of Viscole
A toner was produced in the same manner as in Example 1 using 2 parts by weight of 0p, and the toner performance was examined. As a result, the printed matter was good, with a print density of 1.1 or more and a fog density of 0.09 or less, both at the initial stage and after printing 200,000 copies. Also, no printing damage occurred due to contact with the soft vinyl chloride polymer.

Comparative Example 1 In the manufacturing process of the carboxyl group-containing vinyl polymer of Example 1, an imide group-containing alcohol and para-toluenesulfonic acid were added to an aqueous dispersion medium and the temperature was raised to 90 ± 2 ° C., and then a polymerization initiator was added. The vinyl polymer was added dropwise over about 2 hours and kept at the same temperature for 7 hours. However, no distillation of condensed water was observed, and the carboxyl value was as high as 80, meaning that the esterification reaction did not proceed.

Comparative example 2 Vinyl monomer Weight part styrene
...80.Butyl acrylate
...20 Polymerization initiator benzoyl peroxide ...2 With the above composition, the same polymerization reaction as in the production method of the carboxyl group-containing vinyl polymer of Example 1 was carried out, and subsequently, a vinyl polymer containing no imide group was obtained. .

Next, a toner was obtained using the above vinyl polymer, and the toner performance was examined in the same manner as in Example 1. As a result, printing defects occurred due to contact with the soft vinyl chloride polymer, and the four characters could not be read.

(Effects of the Invention) As is clear from the above Examples and Comparative Examples, the present invention achieves an esterification reaction between a carboxyl group-containing vinyl polymer and an imide group-containing alcohol. By using the imide group-containing vinyl polymer as the binder resin of the toner, printing defects due to compatibility with the soft vinyl chloride polymer can be avoided without impairing toner performance. This has effects such as being able to obtain toner that does not generate any toner.

The present invention is thus a method for efficiently obtaining an imide group-containing vinyl polymer at low cost.

Claims (2)

[Claims] (1) A method for producing an imide group-containing vinyl polymer, which comprises carrying out an esterification reaction between a carboxyl group-containing vinyl polymer and an imide group-containing alcohol. (2) The method for producing an imide group-containing vinyl polymer according to claim 1, wherein the imide group-containing alcohol is a compound represented by the following general formula (A). General formula (A) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ [However, in the formula, R_1 represents an alkylene group having 1 to 6 carbon atoms or a divalent organic group having an alicyclic ring or an aromatic ring,
R_2 has ▲mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R_3 is -CH_
2-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -CH_2CH_2-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or -CH=CH-) or these ]