Yield growth regulators

HydroxyethyUiydrazine (11) is a plant growth regulator. It is also used to make a coccidiostat, furazoHdone, and has been proposed, as has (14), as a stabilizer in the polymerization of acrylonitrile (72,73). With excess epoxide, polysubstitution occurs and polyol chains can form to give poly(hydroxyaLkyl) hydrazines which have been patented for the preparation of cellular polyurethanes (74) and as corrosion inhibitors for hydrauHc fluids (qv) (75). DialkyUiydrazines, R2NNH2, and alkylene oxides form the very reactive amineimines (15) which react further with esters to yield aminimides (16) ... 

Methoprene is an insect growth regulator and it is also used as an insecticide for cockroaches. The enantioselective isomerization of 7-methoxygeranylamine in the presence of [Rh((+)-BINAP)2]+ followed by acid hydrolysis provides the intermediate, 7-methoxycitronellal, in high yield with high optical purity (97%, 98% ee, Scheme 6).9 Alternatively, methoxylation of ( -citronellalenamine (98% ee) with methanol in the presence of 97% sulfuric acid followed by hydrolysis gives 7-methoxycitronellal in 79% yield without racemiza-tion (Scheme 6).9... 

Ultraviolet irradiation of the fungicide and plant growth regulator 69 in solution yields four products, with overall conversion of 37% in 3 days. The photodimer 70, which is the product obtained in lowest yield in solution, is obtained as the sole product (quantitative yield) after only 5 hrs of irradiation of the solid (149). 

The Rh(I)-catalyzed isomerization of prochiral allylic amines to optically active enamines is used for the giant-scale synthesis of citronellal, citronellol, menthol, and other fragrances (18)(Chapter 3). 7-Meth-oxydihydrocitronellal, thus prepared, is an insect growth regulator. All of these processes can be carried out economically and with extremely high optical yields. 

In the 1960 s, 2,3,5-triiodobenzoic acid was considered a spectacular plant growth regulator. When applied to the leaves of soybeans, it shortens the plants, increases their branching, stiffens them, and increases pod set (thus increasing yield). Unfortunately, the compound is not always effective. Scientists have found that the timing of its application is very critical and that different varieties respond differently. Hence, results are disappointingly inconsistent, and the use of this compound to increase soybean yields has been discontinued. 

Plant growth regulators, whether natural occurring or synthetic have been used commercially since the 1950 s. Their uses have generally been to modify growth, enhance yields of food and fiber, adapt plants to scheduled harvest patterns and make certain crops more adaptable to mechanical harvesting. 

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