4450 Hao et al.
Asian J. Chem.
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The aqueous solution of sodium phosphate was heated to
55 °C, then the 3-chloro-2- hydroxy-propane sulfonic acid
sodium was added to the solution7. The product was cooled
after 4 h, and filtered. The filtrate was distilled under reduced
pressure to give a waxy 2,3-oxiranemethane sulfonic acid
sodium salt. The yield was 85.2 %.
The four-necked flask equipped with lauric acid, a moderate
amount of water and quaternary ammonium salt (catalyst) was
stirred and heated to 90 °C, then epoxy propanesul-fonate
solution was added dropwise to the four-necked flasks, droping
about 0.5 h, reaction 2.5 h maintained at 90 °C. The solution
was cooled and filtered to give crude product. The crude product
was recrystallized from ethanol to give the product as a white
powder in a yield of 85 %.
1.00
1.05
1.10
1.15
1.20
1.25
1.30
1.35
nn(sodium hydrogen sulfite):n(epichlorohydrin)
RESULTS AND DISCUSSION
Fig. 2. Effect of the molar ratio on the yield
Influence factors for synthesizing 3-chloro-2-hydroxy-
propanesulfonate
n (sodium hydrogen sulfite): n (epichlorohydrin) is 1.15:1,
the maximum yield of the product is 80.6 %. then yield tends
to be gentle.
Temperature:We explored the effects of reaction tempe-
rature on the yield of product on the condition that the reaction
time was 3.5 h, the molar ratio of the reactants was 1.15:1
(Fig. 1).
Effect of loading sequence on the yield and reaction
time: The experiment shows that adding dropwise epichloro-
hydrin to the aqueous solution of sodium bisulfite is beneficial
to the yield. As the sodium bisulfite is a good nucleophilic
reagent, the aqueous solution of sodium dithionite has a certain
concentration of H+, the acidic environment makes the epoxy
ring oxygen protonated, the C-O bond weaken, and ring carbon
atom with a positive charge. that increases the ability to bind
with a nucleophilic reagent, epichlorohydrin ring-opening
reaction is easily performed9. The yield is improved. Conver-
sely, if sodium bisulfate is added dropwise to epichlorohydrin.
the acidic environment in the initial stage of the reaction is
weak, the reaction does not proceed in a timely manner, and
thus reaction time is long, the yield is relatively low.
Fig. 1 showed that the reaction temperature increases, the
yield rises at first and then gradually reduces.When the reaction
temperature is below 75 °C, the sulfonating agent can not be
fully dissolved and affects the reaction proceeding8, and the
yield rises gently. When the temperature is higher than 85 °C,
with the reaction temperature increases, the yield slightly
decreases. Partial decomposition of sodium bisulfite at high
temperatures reduces the effective concentration of the sulfona-
ting agent. Epichlorohydrin, being also prone to self-polymeri-
zation reaction, results in the increasing of by products. These
factors make yield decreases. When temperature is 85 °C, the
maximum yield of the product is 80.6 %.
Influence factors for synthesizing the main product lauric
acid-2-hydroxy-3-propane sulfonic acid sodium salt
Catalyst screening: We explored the effects of different
catalysts (mass fraction 1.2 %) on the esterification reaction
on the condition that the reaction temperature was 90 °C,
reaction time was 3 h, n (epoxy propane sulfonate): n (lauric
acid) was 1:1.1, the data was shown in Table-1.
80
70
60
50
40
30
TABLE-1
EFFECT OF DIFFERENT CATALYSTS ON THE YIELD
Catalysts
Yield (%)
68.6
Sixteen alkyl trimethyl ammonium bromide
Benzyl trimethyl ammonium chloride
Benzyl triethyl ammonium chloride
78.3
85.2
Table-1 showed that when the other conditions are the
same, benzyl triethyl ammonium chloride is used as a catalyst,
the yield is higher than the previous two catalysts, so the
experiment used benzyl triethyl ammonium chloride.
65
70
75
80
Temperature (°C)
Fig. 1. Effect of the reaction temperature on the yield
85
90
95
Condition experiment: We have investigated the effect
of the amount of catalyst, reaction temperature, reaction time
and the molar ratio of on the product yield.As shown in Table-
2. When the w (catalyst) is 1.2 %, the T is 90 °C, the reaction
time is 3 h and the molar ratio of epoxy propane sulfonate and
lauric acid is 1:1, the yield is the highest, up to 85.2 %.
Reactant molar ratio: Effect of the molar ratio of sodium
bisulfite and epichlorohydrin on the yield is shown in Fig. 2.
Fig. 2 showed that when the reaction time is 3.5 h, the
reaction temperature is 85 °C and other conditions, the yield
rises with increasing the molar ratio of sodium bisulfite. when