SU791722A1 - Dibromotetramethyl-para-sexiphenyl as luminescent compound and its preparation method - Google Patents

Description

The invention relates to new chemical compounds-derivatives of p-polyphenylenes, namely to dibromo-aqueous tetramethyl-substituted p-sexiphenyl of the general formula. 5

Where R is bromine;

R * is methyl;

η = 4, 15 and the method for its preparation.

Dibromotetramethyl-p-sexiphenyl is a luminescent substance and can be used as a phosphor. 20

It is known to use dibromo-tetra-methyl-substituted p-quinquiphenyl as a luminescent substance used in the manufacture of high-speed plast-25 mass scintillators (PS). However, the compound does not have a sufficiently high quantum yield (0.67) and is not a sufficiently active luminescent substance. thirty

The aim of the invention is the search for a new substance with high luminescent properties.

The indicated properties are possessed by the new compound dibromotetramethyl-p-sexiphenyl of the above general formula.

A known method for the preparation of dibromoacetate in water of temethyl e-containing r-quinquiphenyl ad · consists in direct bromination with elemental bromine of a solution of tetramethyl-substituted r-quinquiphenyl at a temperature from 0 to 17 ° C in the presence of iodine. Under the above conditions, the bromination reaction of tetramethyl-p-sexiphenyl could not be carried out, the unchanged starting compound is isolated. The reaction did not pass even at a higher temperature. In good yield, dibromotetramethyl-p-sexiphenyl of the above formula is obtained using iron and iodine powder as catalysts, while using a base to bind hydrogen bromide and a higher temperature.

According to the invention dibromtetrametil-p-seksifenil prepared by direct bromination of tetramethyl-p-seksifenila elemental bromine in the presence of catalysts of iron and iodine at a temperature of 35-55 ^Q C. The reaction is conducted in the presence of an alkali agent karNaydeno,%: C 71.75; 72.12 ', 4.31 5.07', Vg 24.35; 23.60.

^C 40 ^H Si ^{8 g} 2

Calculated,%: C 71.42; H 4.76 ’, G 2 3.80.

sodium bonate to bind hydrogen bromide released during this reaction.

Thus, the difference of this method is as follows: the use of a catalyst - iron powder) the presence in the reaction medium of a base for binding hydrogen bromide;

carrying out the bromination reaction at 35-55 ° C.

Example!. To a solution of 2.57 g * / 6 ®

2,5,2,5-tetramethyl-p-sexiphenyl (mp. 232-237 ° C), 140 ml of chloroform 0.53 g of sodium carbonate, 0.05 g of iron powder and 0.03 g of iodine metal, heated in a water bath up to 35 ° C, 1.1 ml of bromine in 10 ml of chloroform are slowly added dropwise (about 45 min). Then the reaction is continued at a temperature of 35 ° C and stirring for 5 hours. Chloroform is evaporated, the residue is washed with hot water, alcohol, and dried. Obtain 3.1 g (92%) of a light yellow powder;

aluminum and tallization are colored with colorless luminescence. After repeated recrystallization, 0.07 g are isolated; t. pl. 273276 ° C.

Found,%: С 5.00) 8 g 21.30-, ^g g °

Calculated,%:

Wh 23.80.

According to the results of elemental analysis, the isolated substance corresponds to dibromotetramethyl-p-sexiphenyl.

Example 2. To a solution of 2.57 g of tetramethyl-p-seksiphenyl (mp.

'232-237 ° C), 150 ml of chloroform, 1 g: sodium hydroxide, 0.1 g of iron (powder), 0.05 g of iodine at 4 0-45 ° C (temperature of a water bath), 1.1 ml is slowly added bromine in 10 ml of chloroform.

t. pl.

230-260 ° C. Recrystalline - 30 of chlorine benzene with carbon monoxide. After three, 0.35 g (10%) of violet crystals are recrystallized. 270-273 ° C

74.00; 73.32; H, 4.44; 21.02.

C 71.42; H 4.76;

I

UG-,

After bromine was added dropwise, heating was continued for another 7 hours. The precipitate formed was filtered off, washed with hot water, alcohol, dried, and 2.4 g (71%) of a colorless product were obtained; so pl. 275-285 s. After <three recrystallizations from chlorobenzene with aluminum oxide and coal, 1.15 g (^ 34%) of very pure dibromotetramethyl-p-sexiphenyl 'is obtained, mp. 297-298 ⁱⁿ C.

Upon evaporation of chloroform, an additional 1.05 g of a light yellow product is obtained. 230-260 ° C.

PRI me R 3. To a solution of 1.25 g of tetramethyl-p-sexiphenyl (mp. 245-246 ° C), 75 ml of chloroform; 0.5 g of sodium carbonate, 0.05 g of iron, 0.025 g of iodine at 50-55 ° C add 0.6 ml of bromine in 10 ml of chloroform over - ^ 30 min. Heating is continued for 7 hours. The precipitate formed is filtered off, washed with water and alcohol, and dried. 1.15 g of a grayish product are obtained; t. pl. ^ 55-270¾.

After 3 recrystallizations from chlorobenzene with aluminum oxide and coal, 0.25 g (/ - 15%) is obtained; t. pl. 273-276 ^ 0.

The luminescent characteristics for 4 ζ4®, -dibromo-2 5 ¹ , 2 ⁶ , 5 ^{g of} -tetramethyl-p-sexiphenyl in dioxane (with 2.5 ΙΟ ^-4 mol / L) are as follows; ·

Absorption maximum 311 nm (£ = 7.0-10 ⁴ );

Maximum emission 4390 nm; The quantum yield is 0.83.

The lifetime of the excited state is 0.70 ns.

Thus, the synthesized compound has a short lifespan of the excited state and a high quantum yield. The known luminescent compound dibromotetramethyl-p-quinquiphenyl also has a high quantum yield of 0.67 and an excited state life of 0.77 ns. However, it is inferior to the synthesized compound in terms of quantum yield, lifetime of the excited state, and spectral characteristics. In dibromoecramethyl p-quinquiphenyl, the absorption maximum is 301 nm (£ = 6.15 10 * l / mol cm) and the emission maximum is 379 nm.

The shift of the emission spectrum to the long-wavelength side by 11 nm of the synthesized compound, a decrease in the lifetime of the excited state and an increase in the quantum yield by 0.16 significantly improves the luminescent characteristics, which is very important for its practical use.

Claims (2)

Bromination of tetramethyl-p-sexifen la with elemental bromine in the presence of iron and iodine catalysts at a temperature of 35-55s. The reaction is carried out in the presence of an alkaline agent to sodium bonate to bind the hydrogen bromide evolved during this reaction. Thus, the difference of this method consists in the following: the use of a catalyst - iron powder; the presence in the reaction medium of a base for the binding of hydrogen bromide; carrying out the bromination reaction. at 35-55 ° C. Example, To a solution of 2.57 g of f 6 2,5,2,5-tetramethyl-p-sexyphenyl (t. Pl. 232-237s), 140 mp of chloroform, 0.53 g of sodium lactate, 0.05 g of iron powder and 0 , 03 g of metallic iodine, heated in a water bath until, slowly (about 45 minutes) was added dropwise 1.1 ml of bromine in 10 ml of chloroform. Then the reaction is continued at a temperature and stirring for 5 hours. Chloroform is evaporated, the residue is washed with hot water, alcohol, and dried. 3.1 g (92%) of a light yellow color are obtained; t. pl, 230-260 s. Recrystallized from chlorobenzene with alumina and coal. After three recrystallization, 0.35 g (10%) of colorless crystals with violet luminescence is obtained; m.p. 270-273s. After repeated recrystallization, 0.07 g was isolated; m. Pl. 273276 ° C. Found,%: C 74.00, 73.32, H 4, 5.00; 8g 21.30; 21.02. Qe g g, Calculated,% from 71.42; H 4.76, Br 23.80. According to the results of elemental analysis for the isolated substance, dibromotetramethyl-L-sexiphenyl is present. To a solution of 2.57 tetramethyl-p-seciphenyl (mp 232-237 ° C), 150 ml of chloroform, 1 g of sodium sulphate, 0.1 g of iron (powder), 0.05 g of iodine at 40-45 C The temperature of the water bath was slowly dusted with 1.1 ml of bromine in 10 ml of chloroform. After the addition of bromine, heating is continued for an additional 7 hours. The fallen precipitate is filtered off, washed with hot water, alcohol, and sushi gives 2.4 g (71%) of a colorless product; t.pl. 275-285 p. After three recrystallisations from chlorobenzene with alumina and coal, 1.15 g (- 34%) of extremely pure dibromo-tetramethyl-p-ce to synergy is obtained. Mp. 297-298 C. Found,%: C 71.75; 72.12, 4.3i; , 07; Br 24.35; 23.60. 8 --2 Calculated,%: C 71.42 H 4.76, g 23.80. When evaporating chloroform, an additional 1.05 g of a light yellow product is obtained. Mp. 230-260 C. PRI me R 3. To a solution of 1.25 g of etramethyl-p-sexiphenyl (mp. 45-246 C), 75 ml of chloroform; 0.5 g of sodium sulphate, 0.05 g of iron, and 025 g of iodine at 50-55 ° C are added over a period of at least 0.6 ml of bromine in 10 ml of chloroform. Heating is continued for 7 hours. Precipitated. filtered, washed with water, alcohol, dried. 1.15 g of a grayish product are obtained; m.p. 255-270 ° C. After 3-recrystallizations from chlorobenzene with alumina and coal, 0.25 g () is obtained; m.p. 273-276 0. The luminescence characteristics for 4, -dibromo-2, 5, 2, 5 -tetramethyl-p-sexyphenyl in dioxane (from 2.5 x 10 mol / l) are as follows: The maximum absorption 311 nm ten); Emission maximum 4390 nm; The quantum yield is 0.83. The life span of the excited state is 0.70 NS. Thus, the synthesized compound has a short lifespan of the excited state, high quantum yield. The known luminescent compound dibromo-tetramethyl-P-quinquiphenyl also has a high quantum yield of 0.67 and an excited state of 0.77 no lifetime. However, it is inferior to the synthesized compound in terms of quantum yield, lifetime, excited state, and spectral characteristics. Dibromotet; ramethyl-p-quinviphenyl has an absorption maximum of 301 nm (6.15 10 l / mol cm) and a maximum emission of 379 nm. Shifting the emission spectrum to the long wavelength side by 11 nm of the synthesized compound, reducing the lifetime of the excited state, and increasing the quantum yield by 0.16 greatly improves the luminescence characteristics, which is very important for its practical use. Claims 1. Dibromotetramethyl-p-hydroxyphenyl of the formula: where R is bromo. 5 7917226 R is methyl as a luminescent iron and iodine and an alkaline agent centrigo sodium carbonate compound. 2. The method of obtaining compounds According to claim 1, different Sources of information, that tetris 1-methyl-p-sexy phenylprints are taken into account during the examination treated with bromine at 35-55 ° C in- 1. USSR Certificate of Authorship the presence of a catalyst mixture of porous and 480744, cl; From 09 to 1/02, 1973.