ChemicalBook CAS DataBase List 2,3-dichlorobuta-1,3-diene

2,3-dichlorobuta-1,3-diene synthesis

9synthesis methods

Product Name:2,3-dichlorobuta-1,3-diene
CAS Number:1653-19-6
Molecular formula:C4H4Cl2
Molecular Weight:122.98

Cyclopropane, 1,2-dichloro-1-fluoro-2-methyl-

57124-86-4
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1653-19-6
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Yield:1653-19-6 58%

Reaction Conditions:

with alumina at 250; under 760.051 Torr; for 1.08333 h;Flow reactor;Inert atmosphere;Gas phase;

Steps:

Pyrolysis of gem-chlorofluorocyclopropanes 1a-d in the presence of Al2O3.

General procedure: A flow of nitrogen was passed through a flowtubequartz reactor C filled in the middle part with Al2O3 grains (10 g)and heated to 450-550 C at a constant rate of 300 mL min-1 for1 h to activate Al2O3 (remove water), then the reactor was cooledin the flow of N2 to 230 C. 1-Chloro1-fluoro-2,2-dimethylcyclopropane (1a) (10.0 g, 81.6 mmol) was added into the reactor at 230 C in the flow of N2 (70 mL min-1) at a constant rate of0.10 g min-1 over 100 min. The pyrolysis products coming out of the reactor were collected in a trap cooled with a mixture of solidCO2-acetone. The pyrolysate was washed with water and 10%aqueous Na2CO3 and dried with Na2SO4. The residue (7.14 g),containing (GLC and NMR data) 94% of 2chloro3methylbuta1,3diene (3a) and 3% of 2fluoro3methylbuta1,3diene (2a), obtained after removal of the drying agent was distilledat reduced pressure to isolate product 3a (5.67 g, 68%), b.p.46-48 C (145 Torr).

References:

Volchkov;Lipkind;Novikov;Nefedov [Russian Chemical Bulletin,2014,vol. 63,# 10,p. 2250 - 2254][Izv. Akad. Nauk, Ser. Khim.,2014,# 10,p. 2250 - 2254,5]