Description and references
Prepn of cis-form: Buckles, Hausman, J. Am. Chem. Soc. 70, 415 (1948);
Buckles, J. Chem. Educ. 27, 210 (1950); Buckles, Bremer, Org. Synth. coll. vol. IV, 777 (1963); B. H. Patwardhan, G. Bagavant, Indian J. Chem. 10, 59 (1972).
Prepn of cis- and trans-forms: L. F. Fieser, Experiments in Organic Chemistry (Heath,
Boston, 3rd ed., 1955) p 182. Isomerization studies: S. V. Kessar et al., Indian J. Chem. 20B, 4 (1981).
Derivative
cis-Form.
Nomenclature
CAS number: 91-47-4
Properties
Silky needles from ether + petr ether, mp 174°. pKa 6.1 in 60% ethanol. uv max (ethanol): 223, 280 nm (ε 32100, 19500). Sol in hot water, methanol, ethanol, isopropanol, ether, benzene.Derivative
trans-Form.
Nomenclature
CAS number: 91-48-5
Properties
Stout prisms from ether + petr ether, mp 138-139°. Less stable
than the cis-form. pKa 4.8 in 60% ethanol. uv max (ethanol):
222, 289 nm (ε 14500, 22500). More sol
than the cis-form.