http://www.chemistrymag.org/cji/2007/0930013pe.htm |
Mar. 12,
2007 Vol.9 No.3 P.13 Copyright |
Improved synthesis of 2- methyl-naphtho- (1, 2-d) thiazole
Li
Zhanchen , Zhao Aiqin#, Han Xue, Dong Zhimin#, Dou
Lanfeng#
(College of Chemistry and Environmental Science, Hebei University, Baoding, 071002; 1#Min
Ke Environmental Detection of limited company, Baodong 071051)
Abstract: 2- methyl - naphtho-
(1, 2-d) thiazole is an important raw material for the synthesis of spectrum sensitization
additive dye. This compound was synthesized through two intermediate steps: 1- acetyl
amino naphthalene by acetylation and then 1- thioacetyl amino naphthalene by sulfuration
with phosphorus pentasulfide in pyridine. In this work, based on carefully analyzed the
synthetic procedure, the reaction operation conditions were optimized for both the
intermediate steps. Consequently, the purity and yield of both intermediates were greatly
improved.
Keywords: 2- methyl - naphtho- (1, 2-d) thiazole; 1- acetyl amino naphthalene; 1-
thioacetyl amino naphthalene; synthesis
1. INTRODUCTION
Since Vogel discovered that dye had spectrum sensitization-added function in 1873, in more than one
century's time, the synthesis development and application of the spectrum sensitization
additive dye (mainly refers to Cyanine dye) have made the important contribution to the
photosensitive material industry [1]. Until now, the spectrum sensitization
additive dye was still one essential photography organic matter of kinds of new variety
photosensitive material. Therefore, it continuously received the attention in the research
of their synthesis and application both in domestic and abroad.
The spectrum
sensitization additive dye had many types, which could be classified according to their
structure and absorption wave length, such as cation dye, anion dye and neutral dye. For
example, essence dye and styrene dye belong to cation dye.
Since in the molecular structure of cyanine, the chain length of the
conjugated double bond was different, so the dye (340 ~ 1400nm) had different spectral
absorption in the visible light to the near infrared light spectrum region, which had also
formed the custom name of the spectrum sensitization additive dye, there were feeling
blue, feeling green, feeling red and feeling infrared spectrum and so on.
There were many reports about the spectrum sensitization additive dye's
synthesis and application. Such that 2- methyl - naphtho- (1, 2-d) thiazole was applied in
the photosensitive material industry in order to enhance and improve color film feeling
red rock's light sensitivity and color sensitivity. Recently, a lot of synthetic research
work had been made in the process of developing and producing this product.[2]
But the yield still had 8 ~ 10% disparity in comparison with the literature data. In order
to enhance the yield and reduce the production cost, all data of the synthetic steps of
this product were carefully analyzed. The intermediates of this product in first two steps
are1- acetyl amino naphthalene and 1- thioacetyl amino naphthalene.Their synthesis
technics was not stable, sulfuration step was particularly serious, so sulfuration's
product mass fluctuated greatly in yield. Therefore, this article emphasize on the
improved synthesis of these two intermediates.
2. RESULT AND DISCUSSION
2.1 The synthetic route of 2- methyl - naphtho- (1, 2-d) thiazole
2.2 Discussion of the synthesis
2.2.1 1-acetyl amino naphthalene's
synthesis
In the original procedure, after
regurgitation, methyl-naphthalene-amine and acetic anhydride were put into water with
stirring, then they were centrifugated, washed to neutrality and recrystallized from
methanol or ethanol, finally the product was obtained, the purity was 93%, the yield was
85%. This method had two problems:①When 1- acetyl
amino naphthalene was separated from water, it was easy to form hard lump and hard to be
washed thoroughly and dried, it must be recrystallized from methanol or ethanol. Solvent
used in crude product’s recrystallization and the
loss both increased the production cost.②If crude
product was directly smashed and used, the purity was 85%, it had a tremendous influence
to the next step--sulfuration reaction. Using 50% acetic acid solution as medium, it could
take acylation reaction at low temperature. When 1- acetyl amino naphthalene was separated
from the acetic acid solution, the powder produced was easy to be centrifugated, washing
and drying could be conducted directly. Product purity was above 99%, the yield was 90%.
Its shortcoming was increasing the glacial acetic acid amount and making the production
cost increase.
2.2.2 1-thioacetyl amino naphthalene (sulfide for short in this article)
(1) Original synthetic procedure and its problem
In the original procedure, laminated phosphorus pentasulfide was used, 1- acetyl amino
naphthalene and pyridine were separately joined to the reactor, heat up to 110 ~ 115 ℃
and reacted for 45 minutes. After postprocessing there are
many black sticky substances in the product, the purity was 80 ~ 85%, the yield was 73%,
the result seriously affected the next step of oxidized wing closure reaction.
It had two problems:①Using
laminated phosphorus pentasulfide was a defect, because phosphorus pentasulfide assumed
laminated shape, and it was easy to sink and pile up at the base. When the base was heated
partially, it was easy to engender massive heat. If operation was improper, it was easy to
make the material flush.②At the high temperature 115
℃, reacting for 45 minutes was too long, massive
outgrowth were produced, the color of sulfuration product became heavier, the product
purity was lower(usually 80 ~ 85%), the yield was 73%.
(2) Improved synthetic procedure
①Changing phosphorus pentasulfide granularity
Since 1- acetyl amino naphthalene was powdery, so it was evenly mixed
with smashed phosphorus pentasulfide. The two reactants would have intimate contact for
the reaction in pyridine.
The test result indicated that the entire experiment was easy to
control, but because feeding raw material needed a long time(usually 1 ~ 2 hours), so the
final result was not ideal, there were many black matters, the product purity and yield
had not reached the anticipated requirement.
②Changing the way of feeding materials
1- acetyl amino naphthalene and phosphorus pentasulfide were mixed and
added to the reactor, and then pyridine was added, finally stirring was started.
In the entire process, the reaction was steady and easy to control. The
test result indicated that optimal reaction condition was this: reaction temperature was
100 ~ 105 ℃, the reaction time was 15 ~ 30 minutes ,
the product purity and yield enhanced.
When pyridine was joined and stirring was started, the reaction mass
automatically elevated temperature to 60 ℃.When the
reaction mass was heated up to 80 ~ 85 ℃ and added
to pyridine in the fluid, the fluid became thinner and was easy to stir evenly. When the
temperature was elevated to 95 ~ 100 ℃, the color of
the reaction material fluid changed as this rule: light yellow -> red -> garnet.
When the temperature was at 100 ℃, the reaction
fluid gradually stiffened and formed a scarlet red fluid.
③Seeking for the best reaction temperature and time
match to experiment
According to the above test result, at the situation of unchanging
present material ratio, the best reaction temperature and time were sought to achieve the
goal of enhancing sulfuration’s product purity and
yield.
A series of experiments were performed under different temperatures,
and the reaction time was 45min. The results were given in Table 2 and Figure 1.
Table 2 Influence of the reaction temperature on the sulfurated product
Temperature（℃） |
85 |
100 |
105 |
110 |
115 |
Product purity（%） |
85 |
93.8 |
85.5 |
80 |
76 |
Product yield（%） |
60 |
68 |
70.7 |
76.3 |
80 |
Fig.1 Influence of the
As can be seen from
Fig.1, the purity was enhanced along with the reaction temperature. When
the temperature was 100 ℃, the yield was 94% and
then slowly dropped to 76%. The yield unceasingly enhanced along with temperature
increased, but the product purity dropped. This indicated that the purity was higher and
the reaction effect was better when reaction temperature was 100 ℃.
A series of
experiments were performed to investigate the best reaction time, because the reaction
time had more tremendous influence on the extent of reaction. When the reaction
temperature was 100 ℃ and other conditions were
unaltered too(Only the reaction time was changed), the results are shown in Table 3 and
Figure 2. The color of product was deeper and deeper when the reaction time prolonged, the
product purity increased at first and then gradually reduced, and its yield slightly
dropped.
Table 3 Influence of the reaction time on the sulfuration product
Reaction time（min） |
15 |
20 |
30 |
40 |
45 |
50 |
60 |
Product purity（%） |
85 |
88 |
93.9 |
90 |
88 |
86 |
80 |
Product yield（%） |
70 |
73 |
80 |
78.6 |
72 |
70 |
68 |
Fig.2 Influence of the reaction time on the sulfuration product
As can be seen from Fig.2, the product purity changed lower again when the reaction time was longer than 30min, there was one peak(the product purity is 93.9%) when the reaction time was 30 min. The product yield rose from 70% to 80% and then slowly reduced to 68%. Two curves' trends were similar, the optimum reaction time for the yield and purity was 30 min.
The experimental results indicate that when the reaction time was 30 min and the reaction temperature was 100 ℃, the product purity and yield was the ideal result.
Four repeated tests' results were given in Table 4.
Table 4 the results of four tests for the sulfuration reaction
number |
1 |
2 |
3 |
4 |
purity（%） |
93.5 |
94 |
94 |
95 |
Yield（%） |
79.5 |
80 |
81 |
80.5 |
As can be seen from Table 4, the reaction
condition--the reaction temperature and the reaction time were best matched.
(3) Terminating the sulfuration
There were many deficiencies in sulfuration and post-processing in the original procedure.
After reaction ended, the temperature was made low to room temperature with the cold water
for a long time, and along with the temperature dropping, the reactant stiffened and
unable to stir. In the practical process, its quantity was 1000 times. It was cooled in a
caldron, the temperature in the middle of the cauldron body was very difficult to drop, so
this method was used beforetime: when the reaction ended, immediately put it into many
troughs to cool, but its effect was not ideal.
It took a long time that using the 8%NaOH solution to dissolve
coagulated sulfuration product under the room temperature. (Under the high temperature,
dissolving sulfuration with the alkali fluid induced the sulfurated product easy to
decompose and the yield was lower.) So such operation had the shortcoming that the
production cycle was long and product purity was low.
In order to make improvement to the post-processing procedure, the
following improvement was made to the sulfuration post-processing operation: After the
sulfuration reaction finished, the high temperature fluid was immediately put in the quota
ice water (ice was less than water). Sulfuration product formed one softer brown mass (The
temperature was below 20℃ now).The 40% NaOH solution
was added, sulfuration coagulated product dissolved quickly under stirring and turned to
be transparent red solution (temperature was below 35 ℃ now).After calculating, the total volume of such solution was the
same to the original formula. A few insoluble matter were wiped off, and acid was dropped
to let the sulfuration product separate out. After that operation, not only the same
effect was achieved, but also the production cycle was reduced greatly.
2.3 Experimental part
2.3.1 Acylation synthesis
Alpha-naphthylamines (100 g, 0.69 mol) was dissolved in the acetic acid (50%, 2750 mL),
after completely dissolved, one time amount of water was supplied, the temperature was
heated up to 50 ℃, the inner temperature was
controlled at 50 ~ 60 ℃, the acetic anhydride (100
g, 0.8 mol) was added dropwise, and the reaction mixture was stirred for 1 h at 60 ℃.The product was cooled to the room temperature. After the mother
liquor was filtered out, the product was washed to neutral with water. The product was
dried to 116 g (90 % yield), the purity was 99.8%.
2.3.2 Sulfuration synthesis
Thiophosphoric anhydride (24 g) was smashed
and mixed with acylated product (40 g) evenly. The solid raw material was completely added
to the reactor first, and then the pyridine (34 ml) was added. In the reaction mass heat
rose to 76 ~ 80 ℃,
temperature was elevated to 100 ℃, reacted for 30 min at 100 ℃.The reaction mass was put into the ice water (260 mL). It
was stirred for 20 min to be dispersed form, and then it was added to 40% NaOH solution,
cooled to the room temperature, dissolved completely and filtered. The filtrate was cooled
to 0 ~ 5 ℃, 3% acetic
acid solution was added dropwise in 2 ~ 3 h, ph=6 ~ 7.The mother liquor was filtered out
and washed three times with 0.5% vinegar acid, the product was filtered out, and the light
brown powder was obtained. Dry product: 34 ~ 36 grams, purity: 93 ~ 95%, yield: 77 ~ 80%,
melting point: 97~97.5℃. The HPLC Spectrum of the product is shown in Fig.3.The
purity of 2- methyl - naphtho- (1, 2-d) thiazole is very high.
Fig .3 The products HPLC Spectrum
3. CONCLUSION
The two intermediates' improved synthetic procedure was
improved and applicable in the production process. Comparison between the above experiment
and the original result indicate that the yield and purity of product have been
improved.The yield of 1 - acetyl amino naphthalene enhanced from 85% to 90 ~ 92%, and its
purity increased from 93% to 99.7 ~ 99.9%.The yield of 1 - sulfo- acetyl amino naphthalene
increased from 73.9% to 77 ~ 80%, and its purity rose from 80 ~ 85% to 93 ~ 95%.The
practice proved that, fast terminating sulfuration reaction end point reduced sulfuration
production cycle greatly compared with the old method.
REFERENCES
[1] Rongqi Chen, The development and
application of green dye, Printing and Dyeing，2006, (6): 45.
[2] Hamer F M. The cyanine dyes and
related compound [M]. New York: Interscience Publishers Inc., 1964, 198.
[3] Morita, Kosuke, Ebara, Kazuya, New positive-type photosensitive polyimide having sulfo
groups，Polymer, 2003, (44): 20.
[4] Robert E. Buckle M. Peter B. Organic Compound Synthesis [M].Vol.Ⅳ. New York: John Wiley&Sons Inc., 1963, 722.
2-甲基-萘并（1，2-d）噻唑的合成改进研究
李占臣，赵爱琴#，韩雪*，董志民#，窦兰凤#
(河北大学化学与环境科学学院,河北省保定市，邮编071002; 1#河北省保定市民科环境检测有限公司，邮编071051)
摘要
2-甲基-萘并（1，2-d）噻唑是感光材料工业中合成光谱增感染料的重要原材料之一，为了提高该产品的纯度和收率，达到降低生产成本的目的，在分析该产品的生产工艺数据的基础上，认为合成该产品过程中的两个中间体：1-乙酰氨基萘和1-硫代乙酰氨基萘的合成工艺不稳定，数据波动大，尤其是后者更为严重。本文就两个中间体的合成工艺进行了讨论和试验，其试验结果表明：简化和稳定了合成工艺，提高了两个中间体的纯度和收率，并最终在生产中得到验证。
关键词 2-甲基-萘并（1，2-d）噻唑，1-乙酰氨基萘，1-硫代乙酰氨基萘，合成