P-クレゾールに対するトリクロル酢酸の反応

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2

3

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ーノートー

REACTION OF TRICHLOROACETIC ACID WITH P-CRESOL

KIHARA

Ki

y

o

s

h

i

KAMIYA

Hi

r

o

s

h

i

p~ クレゾーノレに対するトリクロル酢酸の反応

清

The authors found a method to prepare a new type of pigment from p-cresol reacted with trichloracetic acid and studied about the chemical structure of the new pigment.

原

木

博

谷

神

solution became deep red and a lot of yellow crystals separated and were identified asふox.y -3・methylbenzaldehydes. 7ml of the same NaOH solution was added and kept being heated at 900C for about 30 minutes. Then the total mass became dark red. The red crystals were filtered using a Buchner funrtel. But the authors found that they were mostly cmposed of aldehydes. And~so the red filtrate was neutralized with dil. HCl to precipitate the pigment. The precipitates were washed well with water until the mineral sub -stances were almost perfectly removed. Then they were dissolved in ethylalchol and developed with a mixed solvent of ethyl alcchol :water (2:1) through an active alumina packed column of 20X2 cm size. The effluent was evaporated， yield :8 %. On the other hand the top -layer of the alumina column absorbed a large quantity of

INTRODUCTION

Though p-cresol is treated by the usual method' of preparing polymethylaurins， we can not obtain the expected pigment， but only black substances are produced. In this study the authors found that the reaction could be smoothly promoted to generate the pigment if some more amounts of NaOH were added again during the process. The product was examined by elementary analysis， UV，V and IR spectroscopy.

1 PREPARATION OF THE

PIGMENT

2

2g of p-cresol was taken in a test tube， 6ml of 50% trichloroacetic acid， 7ml of 335ぢ NaOH added and heated at 80-85.C for ふ10 minutes on a waterbath. At 土his stage the 100 60 20

9

0

80 70 由 u z d A ﹄ O 凹円以︿ 30 340 280 300 Wave Lengrh (mm) UV spectrum of the new pigment

320 260 Fig.1.1 240 10

。

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a characteristic absorption at 470 m m as seen in Fig. 1. 2. But all other polymethyl-aurins had their peaks around 550 mm. Because of this reason we can consider that the configuration of this pigment is quite different. from the others. As seen in Fig. 2， methyl， hydroxyl and aldehyde radicals ga v巴theircharacteristic absorptions at

1870， 3400-3200 2800 cm-1each. The absorption by the aldehyde radical is rather small owing to its interaction with an adjacent OH.

原木

博

pigment. And so this part was cut off and extracted with dil. NaOH at 80"C for a short time. By this treatment almost all of the adsor-bed pigments could be recovered， and were treated by the same method described above， yield :12

%

.

Thus the total yi巴ld became 20

%

.

Elementary analysis gave the same values in the two caces of preparation. ノ，、 '口i 神 232

UV

，

V AND I

R

SPECTROSCOPY

3

An alcoholic solution of this pigment gave 100 UU ロ

E

A

o

Z

︿ 600 450 500 Wave Lengrh (mm)

U V and V spectrum of the new pigment 550 400 0 340 Fig.1.2 100 〉、 o c ; :: 60

Z

VJ z 司払4 h 40 700

I

R

sロectrumof the n巴w pigment

1900 1700 1500 1300 Wave Number (cm-1) 2500 Fig_2 3500 20

。

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PークレゾーJレ1C:対するトリクロJレ酢酸の反応

2

3

3 4 CONSIDERA

TION ON

THE

MECHANISM OF REACITON

AND THE CHEMICAL

STRUCTURE OF PIG

乱

1ENT

When p-cresol reacts with trichloroacetic 1st stage 2nd stage

。

十

q

;

H

0 3@

巳回 CC13COOH 6 NaOH CCl

，

COOH 6 NaOH CC13COOll 5 NaOH acid in an alkaline medium， 9-oxy-3-methylben-zaldehyde is produced at first and then reacts with another trichloroacetic acid to generate a pigment. The mechanism is considered like those in Fig. 3.

。叩阿山

C 1

-

一

→

~ ヤ 4 H

，

0， Na

，

C03 CH3 日日r /

丈

CHO 1¥1

~+

0.N" C 1

一一÷ー→…lC))

'4~H ，~ふ Na2C03 CH， 1八日，C

、

庁

CHO Na， C03 3NaC 1

T

U

二一→

_:_c

_'

_y

_"

_>

_o

₅_H

，

₀ 01(0，え...c'-~ でH， lOJ TOr' i'iや苦;口 .:r: :c 凶 O Fig. 3 Mechanism of th巴Reaction

Besides the two kinds of pigment shown in Fig. 3， we can consider two more which include one or no CHO in a mol巴cule.The results of elementary analysis are shown in Table 1.

Table 1 Elementary Analysis C % H % C25H20 06 2H20 66.3 5.3

C7H~o 03 66.5 4.9 Found 65.6 5‘6

This data suggest that the chemical structure can be a) or b) in Fig 4. a. 令

c

り

だ

。

%合

:

;

9 d

3

b.

偽

造

f

Fig. 4 Chemical Structure assumed

The chemical structur巴b) has no chromophoric

group. And so a) is the most probable one for the pigment. This is a new type pigment diffe -rent from any kind of polymethylaurins， for the reason that its central carbon is bonded with three phenolic compounds at their ortho posi -tions， not para as seen in Fig. 4 a). Aud this pigment is denominated as 3-aldehyde-ふ methyl-benzochinon・(1， 2)ー bis- (3-alde hyde- 4 -oxy

-toluyl)・methid-(5) . Acknowledgment

The authors are very grat巴fulto Mr.G. Yokota for

his help in elementary analysis. References

1) Some parts of this study were presented at the fall general meeting of Japanese chemical society in Tokyo， Octob巴r1971.

2) K.Kihara and others: Kogyo Kagaku Zasshi.