Получения изоцианатов из дифосгена

[Ливерморий]

Здравствуйте, уважаемые химики! Я в отчаянии! Я не могу найти статьи из журналов по нужной мне теме. Искала и на Scopus, и на SD; все тщетно. Может быть, у кого-то другого получится?? Тема: получение изоцианатов из дифосгена по реакции гидрохлорида глицинового эфира с дифосгеном. Буду очень-очень признательна! Ну или хотя бы какие-то сопряженные темы. 

[ZaecЪ]

Нашёл в https://www.google.com/patents/US4548760

Synthesis of N-carbomethoxyglycine ethyl ester isocyanate

 

A solution of phosgene (78.2 g., 1.79 mole) in dry toluene (200 ml) was placed in a three neck flask equipped with a thermometer, reflux condenser and arteries of traps, containing sodium hydroxide, and water. Glycine ethyl ester hydrochloride (55.1 g, 0.395 mole) was added at once. The reaction mixture was refluxed for 3 hrs., during which time HCl gas evolved. The unreacted glycine ethyl ester hydrochloride was filtered and the filtrate containing glycine ethyl ester isocyanate (IR 2250 cm-1) was reacted with an excess of anhydrous methanol for 0.5 hrs. then the solvent was evaporated to obtain N-carbomethoxyglycine ethyl ester.

 

Alternatively, glycine ethyl ester hydrochloride (40.1 g, 0.28 mole) suspended in dry tetrahydrofuran (200 ml) and phosgene were bubbled through the reaction mixture for 0.5 hrs, as the reaction mixture was refluxed. At the end of 0.5 hrs., the reaction was cooled to room temperature and toluene was added followed by the distillation of THF. The reaction mixture containing toluene was further refluxed for 1 hr. The unreacted glycine ethyl ester hydrochloride was filtered and the filtrate containing glycine ethyl ester isocyanate (IR 2250 cm-1) was reacted with excess (2-3 mole) anhydrous methanol and, when the isocyanate peak disappeared, the solvent was removed to isolate N-carbomethoxyglycine ethyl ester.

 

Alternatively, glycine ethyl ester hydrochloride (35.7 g, 0.256 mole) was suspended in dry acetonitrile (300 ml) containing phosgene (50.7 g, 0.512 mole) and the reaction mixture was refluxed. A few drops of dry pyridine was added after 1 hr. of refluxing. Unreacted glycine ethyl ester hydrochloride was filtered off and dry toluene (300 ml) was added then acetonitrile was distilled off. The toluene solution was refluxed for 1 hr. to obtain glycine ethyl ester isocyanate (IR 2250 cm-1). This isocyanate was reacted, without further purification, with anhydrous methanol.

Они в свою очередь ссылаются на Franz, J. E., Glyphosphate and Related Chemistry, Monsanto Agricultural Products Co., St. Louis, Mo. 63166, United States, Adv. Pesticide Sci. Plenary Lect. Symp. Pap. Int. Congr. Pesticide Chem., 4th 1978, (Pub. 1979)

 

Ещё одно упоминание «Ethyl 2-isocyanatoacetate can also be prepared from various glycine derivatives, including the reaction of N-tosylglycine ethyl ester7 or N-trimethylsilylglycine ethyl ester4 with phosgene, or the reaction of glycine ethyl ester hydrochloride with bis(trichloromethyl)carbonate.8»

http://orgsyn.org/demo.aspx?prep=v89p0404

Список литературы там же

 

…и ещё одно:

«The reaction for conversion of the amino groups into isocyanate may be performed by, for example, the method of using di-tert-butyl dicarbonate and dimethylaminopyridine described in Synlett., 1997, 8, 925 etc. and further may be performed by the known isocyanate synthesis method using diphosgene, triphosgene, etc.»