Abstract
From the results obtained from the series of the studies1, 2, 3), the authors have taken interest in the plant hormone activity of 1, 2-dihydro-naphthoic acid-(1). This substance was synthetized by the following new method.
Synthesis of 1, 2-dihydro-naphthoic acid-(1) (IX): 1, 2, 3, 4-Tetrahydronaphthoic acid-(1) (V) or its ester (VI) was brominated with N-bromo-succinimide and then the mono-bromide produced was dehydrobrominated or concurrently hydrolyzed by refluxing with a theoretical amount of 10 per cent solution of methanolic potash. The crude acid obtained (IX and I) was recrystallized from methyl acetate, and pure acid (IX), m.p. 98°, was isolated in a yield of 40-60 per cent of the starting substances (V) or (VI) (cf.
Figure 1). The acid (IX), thus obtain_??_was found to differ remarkably in m.p. fr_??_those substances previously reported by t two workers4, 5). Nevertheless, the followi_??_ experiments, indicate that the newly synth tized acid (IX) is undoubtedly 1, 2-dihydx naphthoic acid-(1).
Confirmation of chemical structure of t_??_acid (IX):
1) Absorbing I mol. of hydrogen throu_??_catalytic hydrogenation, acid (IX) ga 1, 2, 3, 4-tetrahydro-naphthoic acid-(1) qua titatively (Figure 1).
2) Acid (IX) was stable in hot alkali_??_solution, in which 1, 4-dihydro-naphthoic aci (1) (III) was labile to give 3, 4-dihydr naphthoic acid-(1) (IV) (Figure 1).
3) Both dibromo- and dihydroxy-deriv tives of acid (IX) showed higher melti_??_points than those of the homologues deriv_??_from 3, 4-dihydro(IV) and 1, 4-dihydro-nap thoic acid-(1) (III) (Table I).
4) Acid (IX) was oxidized with 1 p cent solution of potassium permanganate stepwise, and phthalic acid (XIII) was fin_??_ly obtained via glycolic acid (XI) and tric_??_boxylic acid (XII) (cf. Figure 2).
Plant growth activity of the acid (IX): T results of plant hormone activity tests rev_??_that the acid is a strong plant hormo substance (Table II).
