Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Alcohols reaction with phosgene

Phosgene reacts with alcohols or phenols (or their simple salt derivatives) to give two types of compound, chloroformates R0C(0)C1 Equation (4.7) and carbonates R0C(0)0R Equation (4.8), see Section 10.3.1. Carbonates are generally derived from the further reaction of the alcohol or phenol with the chloroformate. [Pg.200]

Ureas and Carbonates. Reagent (1) may be used as a direct replacement for the highly toxic Phosgene in reactions with alcohols and amines. Reaction of (1) with two equivalents of a primary aliphatic or aromatic amine at room temperature rapidly yields a symmetrical urea (eq 9). If only one equivalent of a primary amine is added to (1), then the imidazole-Al-carboxamide (4) is formed (eq 10). These compounds can dissociate into isocyanates and imidazole, even at room temperature, and distillation from the reaction mixture provides a useful synthesis of isocyanates (eq 10).7 Secondary amines react only at one side of (1) at room temperature, again giving the imidazole-Al-carboxamide of type... [Pg.73]

Reductive carbonylation of nitro compounds is catalyzed by various Pd catalysts. Phenyl isocyanate (93) is produced by the PdCl2-catalyzed reductive carbonylation (deoxygenation) of nitrobenzene with CO, probably via nitrene formation. Extensive studies have been carried out to develop the phosgene-free commercial process for phenyl isocyanate production from nitroben-zene[76]. Effects of various additives such as phenanthroline have been stu-died[77-79]. The co-catalysts of montmorillonite-bipyridylpalladium acetate and Ru3(CO) 2 are used for the reductive carbonylation oLnitroarenes[80,81]. Extensive studies on the reaction in alcohol to form the A -phenylurethane 94 have also been carried out[82-87]. Reaction of nitrobenzene with CO in the presence of aniline affords diphenylurea (95)[88]. [Pg.538]

The reaction of phosgene with alcohols yields chloroformates, and with a basic catalyst present, carbonates ate formed ... [Pg.312]

The reaction of phosgene (carbonic dichloride [75-44-5]) with alcohols gives two classes of compounds, carbonic esters and carbonochloridic esters, commonly referred to as carbonates and chloroformates. The carbonic acid esters (carbonates), R0C(0)0R, are the diesters of carbonic acid [463-79-6]. The carbonochloridic esters, also referred to as chloroformates or chlorocarbonates, C1C(0)0R, are esters of hypothetical chloroformic acid [463-73-0] CICOOH. [Pg.37]

Based on the well-known reaction of phenoxazine with phosgene,15 leuco Basic Blue 3 was treated with phosgene to form the stable 10-chlorocarbonyl-3,7-diethylaminophenoxazine (39) which can be isolated and further reacted with alcohol or amine.16... [Pg.81]

Conversion of the amino alcohol 53 to Efavirenz (1) was readily accomplished by reaction with phosgene or phosgene equivalents. The most convenient and economically sound method is to react 53 with phosgene in the absence of base in THF-heptane at 0-25 °C. After aqueous work-up, Efavirenz was crystallized from THF-heptane in excellent yield (93-95%) and purity (>99.5%, >99.5% ee). [Pg.28]

A series of reactions with gases have been selected for the rapid quantification of many of the major products from the oxidation of polyolefins. Infrared spectroscopy is used to measure absorptions after gas treatments. The gases used and the groups quantified include phosgene to convert alcohols and hydroperoxides to chloroformates, diazomethane to convert acids and peracids to their respective methyl esters, sulfur tetrafluoride to convert acids to acid fluorides and nitric oxide to convert alcohols and hydroperoxides to nitrites and nitrates respectively. [Pg.376]

The replacement of both -OH groups with chlorine produces Ccirbonyl dichloride, also known as phosgene, a useful reactant. For example, phosgene reacts with two moles of alcohol to form a dialkyl carbonate. The reaction of phosgene with one mole of alcohol produces an alkyl chloroformate, which is a useful intermediate in organic syntheses. The reaction of phosgene with four moles of ammonia yields urea and two moles of ammonium chloride, NH Cl. Figure 12-40 shows the structures of some of these compounds. [Pg.213]

Amines can be linked to polymeric alcohols as carbamates. Carbamate attachment of amines can be achieved by reaction of isocyanates with alcohol linkers, or by treatment of alcohol linkers with phosgene [339,427,428] or a synthetic equivalent thereof, followed by exposure to the amine (Figure 3.26). The reagents most commonly used for the activation of alcohol linkers are 4-nitrophenyl chloroformate [69,429-436] and carbonyl diimidazole [427,437-440], The preparation of support-bound carbamates is discussed in Section 14.6. [Pg.87]

Alcohols and phenols can be attached to support-bound alcohol linkers as carbonates [467,665,666], although few examples of this have been reported. For the preparation of carbonates, the support-bound alcohol needs to be converted into a reactive carbonic acid derivative by reaction with phosgene or a synthetic equivalent thereof, e.g. disuccinimidyl carbonate [665], carbonyl diimidazole [157], or 4-nitrophenyl chloro-formate [467] (see Section 14.7). The best results are usually obtained with support-bound chloroformates. The resulting intermediate is then treated with an alcohol and a base (DIPEA, DMAP, or DBU), which furnishes the unsymmetrical carbonate. Carbonates are generally more resistant towards nucleophilic cleavage than esters, but are less stable than carbamates. Aryl carbonates are easily cleaved by nucleophiles and are therefore of limited utility as linkers for phenols. [Pg.112]

The preparation of carbonates is mechanistically closely related to the synthesis of carbamates, and similar reagents can be used for this purpose (Table 14.10). Resin-bound alcohols can be directly converted into carbonates by treatment with a chloro-formate (see Experimental Procedure 14.2), in two steps by activation with phosgene or a synthetic equivalent thereof followed by reaction with an alcohol in the presence of a base, or by treatment of a resin-bound alcohol with carbon dioxide and an alkyl halide under basic reaction conditions [125]. Thiocarbonates can be prepared from... [Pg.383]

Carbonate and carbamate derivatives, prepared from the reaction of alcohols and amines with phosgene and /V-hydroxy-2-thiopyridone, provide the corresponding alkoxyl radicals and aminyl radicals respectively, via radical decarboxylation [71-81]. For example, photolytic treatment of carbamate (57) derived from 4-pentenylamine generates the corresponding 4-pentenylaminyl radical, as shown in eq. 8.24. Under neutral conditions in the presence of tert-BuSH, a direct reduction product (A) of 4-pentenylaminyl radical is formed, while, in acidic conditions, cyclized product (C), pyrrolidine, via 5-exo-trig manner from 4-pentenylaminyl radical is formed. Under the latter conditions, the real reactive species is an electrophilic 4-pentenylaminium radical which rapidly cyclized via 5-exo-trig manner. [Pg.211]

Chloroformates, prepared by controlled reaction of phosgene with alcohols, are decar-boxylated in presence of ammonium, phosphonium or sulfonium salt catalyst (equation 170)1092. [Pg.600]

DOT CLASSIFICATION 6.1 Label Poison SAFETY PROFILE A poison by ingestion, inhalation, skin contact, intraperitoneal, intravenous, and subcutaneous routes. Moderately toxic to humans by inhalation. It can affect the nervous system, liver, spleen, and lungs. An experimental teratogen. Mutation data reported. A severe eye and mild skin irritant. Flammable liquid when exposed to heat, flame, or oxidizers. To fight fire, use alcohol foam, CO2, dry chemical. Violent reaction with chlorosulfonic acid, ethylene diamine, sodium hydroxide. Reacts with water or steam to produce toxic and corrosive fumes. Potentially violent reaction with oxidizing materials. When heated to decomposition it emits highly toxic fumes of CT and phosgene. See also CHLORINATED HYDROCARBONS, 7M.IPHATIC. [Pg.622]

Syntheses of N-arylurethanes and N,N -diarylureas for an approach to phosgene-free isocyanates could be accomplished by ruthenium complex-catalyzed dehydro-genative reactions of N-arylformamides, which are prepared by the carbonylation of aminoarenes (see Eq. 11.8), with alcohols [106] and aminoarenes [107], respectively. [Pg.294]


See other pages where Alcohols reaction with phosgene is mentioned: [Pg.108]    [Pg.154]    [Pg.48]    [Pg.67]    [Pg.338]    [Pg.16]    [Pg.224]    [Pg.40]    [Pg.38]    [Pg.18]    [Pg.26]    [Pg.363]    [Pg.57]    [Pg.132]    [Pg.425]    [Pg.459]    [Pg.94]    [Pg.26]    [Pg.325]    [Pg.265]    [Pg.340]    [Pg.265]    [Pg.105]    [Pg.105]    [Pg.470]    [Pg.693]    [Pg.452]    [Pg.157]    [Pg.45]   
See also in sourсe #XX -- [ Pg.146 ]




SEARCH



Alcohols phosgene

Amino alcohols reaction with, phosgene

Benzyl alcohols reaction with phosgene

Carbonates from phosgene reaction with alcohols

Phosgenation reaction

Phosgene, reaction

Primary alcohols reaction with, phosgene

Reaction with alcohols

Reaction with phosgene

Secondary alcohols reaction with, phosgene

Tertiary alcohols reaction with, phosgene

With phosgene

© 2024 chempedia.info