Isoprene synthesis
- Product Name:Isoprene
- CAS Number:78-79-5
- Molecular formula:C5H8
- Molecular Weight:68.12
In the first step, propylene is dimerized to 2-methyl-l-pentene by passage over a catalyst of tri-n-propylaluminium at about 200°C and 20 MPa (200 atmospheres). This product is then isomerized to 2-methyl-2-pentene by heating at 150-300°C in the presence of a silica-alumina catalyst. The final step in the process is the pyrolysis of the olefin to isoprene at 650-800°C in the presence of a free radical initiator such as hydrogen bromide. The isomerization step is necessary because pyrolysis of 2-methyl-l-pentene gives much poorer yields of isoprene than pyrolysis of 2-methyl-2-pentene.
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Yield:78-79-5 98.6%
Reaction Conditions:
with supported heteropolyacid in tert-butyl alcohol at 160; under 71257.1 Torr;Pressure;Temperature;
Steps:
3 Example 3
In a reaction column synthesizing 4,4-dimethyl-1,3-dioxane,Pressure is 1.0MPa,The temperature is 92 ,Molar flow ratio of C4 fraction containing isobutylene and formaldehyde is 1, butyrolactam is added,The quality of the total system mass of 0.05.In the presence of a catalyst of sulfonated silica, the yield of 4,4-dimethyl-1,3-dioxane formed reached 94.6%. In the synthesis of t-butanol in the reaction tower,Pressure is 1.8MPa,Reaction temperature is 70 ,The molar flow ratio of water to the C4 fraction is 2,The concentration of isobutylene in C4 was 38.9%With cationic resin as catalyst,The yield of t-butanol obtained by countercurrent reaction reached 86%.The 4,4-dimethyl-1,3-dioxane and t-butanol produced by the reaction were heated at 160 ° C,9.5MPa conditions,The molar flow ratio of isobutanol to 4,4-dimethyl-1,3-dioxane was 5,In the presence of supported heteropolyacid,Isoprene generated less impurities, yield 98.6%.The purity of isoprene obtained was 99.60%.
References:
CN104876786,2017,B Location in patent:Paragraph 0005; 0030-0035
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