Urethane, ethyl, reaction with

Ethyl N-tricarboxylate has been prepared from urethan by reaction with sodium and chlorocarbonic ester1 as well as from the potassium salt of ethyl imidodicarboxylate.2... 

Methanol is oxidized to formate ions, acetone and acetaldehyde to acetate species. An enolic form of adsorbed acetone is seen, which accounts for rapid isotopic exchange of -OH. On O2 adsorption two bands at 1155 and 1020 cm are formed,which are however not assigned. Mixtures of CO plus O2 lead to the obvious formation of carbonates and bicarbonates. CO interaction with presorbed NH3 forms carbamate species. Oxidizing properties of the surface are shown by the reaction of trichloroacetone to trichloroacetate species. Nitriles are, however, hydrolysed to acetimidate species R-CNH . Similar reactions with surface -OH are shown by ethyl and phenyl isocyanate, which form urethanes by reaction with isolated -OH groups, and 1,3-diethylurea with -OH pairs. Reaction with surface -OH is also shown by trimethylchlorosilane, which, however, harshly attacks the surface and forms silicone species. ... 

With Af-acyl or Af-sulfonyl hydrazines as nucleophiles, Zincke salts serve as sources of iminopyridinium ylides and ylide precursors.Reaction of the nicotinamide-derived Zincke salt 8 with ethyl hydrazino urethane 42 provided salt 43, while the tosyl hydrazine gave ylide 44 (Scheme 8.4.14). ° Benzoyl hydrazines have also been used in reactions with Zincke salts under similar conditions.Af-amino-1,2,3,6-tetrahydropyridine derivatives such as 47 (Scheme 8.4.15), which showed antiinflammatory activity, are also accessible via this route, with borohydride reduction of the initially formed ylide 46. ... 

Works on the oxidation of uric acid has unequivocally established the triazine structure > ° (9) of oxonic acid. This is further confirmed by the straightforward synthesis described by Piskala and Gut. ° The reaction of biuret (11) with potassium ethyloxalate yielded a potassium salt (24), that with ethyl oxamate, the amide of oxonic acid (25). Both these compounds were converted to 5-azauracil. An analogous reaction with diethyloxalate which should produce an ester of oxonic acid resulted in a mixture of urethane and parabanic acid, however. 

The structural effect of alkyl groups such as methyl, ethyl, and -butyl on the Rp is small. Alkyl 4-methyl-phenylcarbamate can be chosen as a model compound for the hard segment of poly(ether-urethane) (PEU). This group can initiate grafting reaction with Ce(IV) ion and the grafting site was proposed at the hard segment of PEU [3,15] as shown in Scheme (1). 

Occasionally, N-acylation is the predominant reaction with acyl halides. Thus ethyl chloroformate or diethyl carbonate on reaction with (171c) leads only to the urethane (200) (91T497). 

Pyrrolidines piperidines.7 Reaction with benzeneselenenyl chloride converts A4-and As-unsaturatcd ethyl urethanes into phcnylseleno-substituted pyrrolidines and piperidines, respectively. Yields are considerably improved by the presence of silica gel, which presumably facilitates the ring closure subsequent to addition of the reagent to the double bond (equation I). 

They also described the reaction of diketene with N,N-dimethylurea in acetic acid, yielding 50 (see also Ahmed et a/.177). Gunar et a/.178 used diketene in the reaction with cyanic acid (see also Ozaki179), thiocyanic acid, ethyl urethane, and N,N -disubstituted ureas in acetic acid medium to obtain 50. When a 2-thiono derivative was obtained from thiocyanic acid, as in Eq. (37), they desulfurized it with mercuric acetate. 

In bonding wood, the reaction of isocyanate groups with the numerous hydroxyl groups that are present in the various components of wood—cellulose, hemicellulose, and lignin—is possible. The product of this chemical reaction with wood is the urethane bond as shown in Reaction I. Methyl, ethyl, propyl, and butyl isocyanates... 

A special technique of trimerization has been described by Kogon 24, 25). Phenyl isocyanate reacts with ethyl alcohol to form a urethane (ethyl carbanilate). At 125° a substantial yield of ethyl a,7-diphenyl allophanate is observed as well as a small amount of phenyl isocyanate dimer. However, when A-methyhnorpholine (NMM) is added as a catalyst, the reaction is altered and the product is triphenylisocyanurate (isocyanate trimer) in high yield. The reaction sequence is believed to be ... 

Dithiazines, urethanes, or iminocarboxylic acid esters result from the reaction of ethyl azidoformate with l,2-dithiole-3-thiones.232... 

Brown and Edwards33 irradiated a mixture of dihydropyrane and ethyl azidoformate and obtained in good yield a highly reactive product (not purified) shown to be the aziridine (6) by reaction with water to give the urethane (7). 

Methyl-2-propyl-l, 3-propanediol is prepared by reacting diethyl methylpropyl malonate in ether in the presence of lithium aluminium hydride and then treated with dilute sulphuric acid. This on treatment with phosgene in toluene by means of dimethylaniline yields 2-methyl-2-propyl-3 -hydroxypropyl chlorocarbonate, which on reaction with n-butylamine forms 2-methyl-2-propyl-3-hydroxypropyl butylcarbamate. The resulting product on treatment with ethyl urethane in the presence of aluminium isopropoxide in boiling xylene yields ethanol during transesterification which is removed from the reaction mixture simultaneously and tybamate is obtained. 

These are made by reacting an acrylate monomer with the diisocyanate, usually in the presence of a catalyst such as dibutyltin dilaurate. An example of a typical urethane acrylate reaction which results in a flexible elastomer, based on hydroxy ethyl acrylate, is shown in Fig. 12.12. 

Through urethane bond hydrolysis, LDI-based PURs release L-lysine ethyl ester, a non-toxic degradation product, as a result of LDI reaction with water (Skaija et al.,... 

Diethyl dicarbonate (diethyl pyrocarbonate) was used in the past as a preservative for soft drinks and some alcohohc beverages (including wine). In aqueous solution, however, diethyl dicarbonate is rapidly hydrolysed to ethanol and carbon dioxide, and in alcoholic beverages it is transformed into diethyl carbonate by reaction with ethanol. In the presence of ammonium salts toxic ethyl carbamate then results, which is also known as urethane (Figure 11.2). For these reasons, diethyl dicarbonate is not approved in the EU, but the approved compound is dimethyl dicarbonate (E242), which can be used for the preservation of soft drinks, teas, herbal teas and in some countries to stabilise wine. The methyl carbamate produced from dimethtyl dicarbonate is a non-toxic substance. In treated wines it occurs in amounts up to 10 xg/l. 

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