Environmental Engineering Reference
In-Depth Information
CH
2
OH
CH
2
OH
CH
2
OH
CH
2
ONO
2
HBr
NaN
3
HNO
3
HOH
2
C
C
CH
2
OH
BrH
2
C
C
CH
2
Br
N
3
H
2
C
C
CH
2
N
3
N
3
H
2
C
C
CH
2
N
3
CH
2
OH
CH
2
OH
CH
2
OH
CH
2
ONO
2
(PB)
(PA)
(PDADN)
CH
2
OH
CH
2
OH
CH
2
OH
CH
2
ONO
2
HBr
NaN
3
HNO
3
HOH
2
C
C
CH
2
OH
BrH
2
C
C
CH
2
Br
N
3
H
2
C
C
CH
2
N
3
N
3
H
2
C
C
CH
2
N
3
CH
2
OH
CH
2
OH
CH
2
OH
CH
2
ONO
2
(PB)
(PA)
(PDADN)
28 kg pentaerythritol, 100 kg 45 % HBr solution and 20 kg acetate acid are
added into the reactor with mechanical stirring, thermometer and re
fl
ux condenser,
heated to 115
C, and reluxed for 6 h. After reaction, water and excess HBr are
evaporated under reduced pressure. The mixture is cooled down to room temper-
ature, neutralized by base, and treated by the solution of methylbenzene and water.
49 kg pentaerythritol dibromohydrin (PB) is obtained after
°
filtration and drying
with melting point 108
C. The yield is 94.26 %.
131 kg PB, 72.5 kg NaN
3
and 175 DMF are added into a 250 L reactor, heated to
120
109
°
-
5 h. After reaction, DMF is evaporated under reduced pressure.
100 L dichloromethane is added. After
°
C, and react 2
-
filtration, the dichloromethane mother liquid
with PA is collected for next reaction. The yield of this step is up to 97 %.
The dichloromethane with PA is added into the reactor with thermometer and
mechanical stirring, and statistic HNO
3
is added drop by drop at 10
15
°
C. After
-
10
15 min reaction, the mixture is poured into ice water, and organic layer is
separated. The organic products are
-
first washed two times by 100 L water, then one
time by 50 L of 2 % NaHCO
3
,
finally DI water to be neutral. The dichloromethane
with PDADN is dried using anhydrous MgSO
4
. After solvent evaporation, 12.64 kg
PDADN is obtained with yield 93.5 %. It has melting point of 39
41
°
C and purity
-
of 98.55 %.
There are some challenging technical problems in the synthesis and preparation,
which are discussed below.
(1) PB separation in the synthesis processes
There are probably nonreactant pentaerythritol, bromopentaerythritol, trib-
romopentaerythritol, tetrabromopentaerythritol, etc. PB is not dissolved in water
and methylbenezene; while pentaerythritol and bromopentaerythritol are dissolv-
able in water, and tribromopentaerythritol and tetrabromopentaerythritol are dis-
solved in toluene. PB is conveniently separated using the same volume of toluene
and water mixture, and puri
ed using recrystallization in hot water.
(2) The in
fl
uence of nitri
cation coef
cient for the yield of PDADN
Because nitri
cation coef
cient in
fl
uences the yield of nitri
cation reaction, the
yield is studied under different nitri
cation coef
cient and the same reaction tem-
perature. The results are in Table
6.9
.
The data in Table
6.9
indicates that the yield of PDADN increases following the
increment of nitri
cation coef
cient. When the nitri
cation coef
cient is larger than
