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ISOCYANIC ACID, ANHYDRIDE WITH

ISOCYANIC ACID, ANHYDRIDE WITH CHIO ROACETIC ACID, 46, 16 ISOCYANIC ACID, ANHYDRIDF WITH CHLOROSULPONIC ACID, 46, 23 Isocyanides, preparation of volatile, 46, 77... [Pg.131]

Isocyanic acid, anhydride with chlo-ROACETIC acid, 46, 16 Isocyanic acid, anhydride with ClII-OROSULKONIC ACID, 46, 23... [Pg.73]

CHLOROSULFONYL ISOCYANATE (Isocyanic acid, anhydride with chlorosulfonic acid)... [Pg.23]

In general, 3-hydroxy-l,2,4-thiadiazoles react with hard nucleophiles (acid chlorides, sulfonyl chlorides) at the oxygen atom, whereas soft nucleophiles (isocyanates, acid anhydrides) react at the N-2 position yielding 1,2,4-thiadiazolin-3-ones. Nucleophiles react at the N-4 position of 5-hydroxy-l,2,4-thiadiazoles <1996CHEC-II(4)307>. There have been no new publications on O-linked substituents since the publication of CHEC-II(1996). [Pg.499]

Benzenesulfonyl isocyanate, 4-methyl- EINECS 223-810-8 Toluenesulfonic acid, anhydride with isocyanic acid Toluenesulfonyl isocyanate p-Toluenesulphonyl isocyanate. [Pg.624]

Trichloroacetic acid anhydride with isocyanic acid, SCI [3019-71-4]... [Pg.914]

Rea.ctlons, As with other tertiary alcohols, esterification with carboxyUc acids is difficult and esters are prepared with anhydrides (181), acid chlorides (182), or ketene (183). Carbamic esters may be prepared by treatment with an isocyanate (184) or with phosgene followed by ammonia or an amine (185). [Pg.112]

Carboxyhc acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthahc acid [88-99-3J, react with aryl isocyanates to yield the corresponding A/-aryl phthalimides (73). Reactions with carboxyhc acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature appHcations where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). [Pg.452]

Chemical Properties The formation of salts with acids is the most characteristic reaction of amines. Since the amines are soluble in organic solvents and the salts are usually not soluble, acidic products can be conveniendy separated by the reaction with an amine, the unshared electron pair on the amine nitrogen acting as proton acceptor. Amines are good nucleophiles reactions of amines at the nitrogen atom have as a first step the formation of a bond with the unshared electron pair of nitrogen, eg, reactions with acid anhydrides, haUdes, and esters, with carbon dioxide or carbon disulfide, and with isocyanic or isothiocyanic acid derivatives. [Pg.198]

In addition to the proteins discussed above, a large number of reactive chemicals used in industry can cause asthma and rhinitis. Hypersensitivity pneumonias have also been described. Isocyanates and acid anhydrides are industrial chemicals that cause occupational asthma. Acid anhydrides, such as phthalic anhydride, seem to cause mainly type I reactions, whereas the IgE-mediated mechanism explains only a part of the sensitizations to isocyanates. Several mechanisms have been suggested, but despite intensive research no models have been generally accepted. The situation is even more obscure for other sensitizing chemicals therefore, the term specific chemical hypersensitivity is often used for chemical allergies. This term should not be confused with multiple chemical sensitivity (MCS) syndrome, which is a controversial term referring to hypersusceptibility to very low levels of environmental chemicals. ... [Pg.310]

Respiratory hypersensitivity is an adverse reaction in the respiratory tract driven by immune mechanisms such as IgE antibody mediated allergic responses. Other less well understood mechanisms that have an immune component are also involved in respiratory hypersensitivity. OA is one outcome of respiratory hypersensitivity. Respiratory hypersensitivity and OA to proteins are primarily mediated by IgE antibody with subsequent inflammatory cell infiltrates. This same mechanism is responsible for OA to specific LMW chemicals such as the acid anhydrides and platinum salts. However, the role for IgE mediated responses in OA to other LMW chemicals such as the isocyanates and plicatic acid is poorly defined and other mechanisms may be responsible. [Pg.576]

The pyrido[3,2-rflpyrimidines 370 were prepared from 2,3-pyridinedicarboxylic acid anhydride 366 by the action of boiling MeOH to give the stable isomer of half-ester 367. Subsequent treatment with ethyl chloroformate in presence of EtsN and NaNs formed the azide 368 that was transformed by Curtius rearrangement into the isocyanate 369. Reaction of 369 with a series of amino acids under mild conditions gave adducts 370 (Scheme 12) <2003TL2745>. [Pg.799]

While metallocenes are usually acetylated with acid halides, acid anhydrides, or carboxylic acids, a number of other acylating agents have been reported. The reaction of ferrocene with various isocyanates and aluminum chlorides leads to N-substituted ferrocenecarboxamides (IX) (89). Use of ruthenocene in place of ferrocene leads to analogous results (88). The preparation of V-phenyl-ferrocenecarboxamide from phenyl isocyanate in this manner has been used as a proof of structure for the product obtained from the Beckmann rearrangement of benzoylferrocene oxime (124). [Pg.64]

Initially, water can cause the hydrolysis of the anhydride or the isocyanate, Scheme 28 (reaction 1 and 2), although the isocyanate hydrolysis has been reported to occur much more rapidly [99]. The hydrolyzed isocyanate (car-bamic acid) may then react further with another isocyanate to yield a urea derivative, see Scheme 28 (reaction 3). Either hydrolysis product, carbamic acid or diacid, can then react with isocyanate to form a mixed carbamic carboxylic anhydride, see Scheme 28 (reactions 4 and 5, respectively). The mixed anhydride is believed to represent the major reaction intermediate in addition to the seven-mem bered cyclic intermediate, which upon heating lose C02 to form the desired imide. The formation of the urea derivative, Scheme 28 (reaction 3), does not constitute a molecular weight limiting side-reaction, since it too has been reported to react with anhydride to form imide [100], These reactions, as a whole, would explain the reported reactivity of isocyanates with diesters of tetracarboxylic acids and with mixtures of anhydride as well as tetracarboxylic acid and tetracarboxylic acid diesters [101, 102]. In these cases, tertiary amines are also utilized to catalyze the reaction. Based on these reports, the overall reaction schematic of diisocyanates with tetracarboxylic acid derivatives can thus be illustrated in an idealized fashion as shown in Scheme 29. [Pg.150]

Reactivity. Flammable polymerizes violently in the presence of trace amounts of metals or acids can react violently with acid anhydrides, alcohols, ketones, phenols, ammonia, hydrocyanic acid, hydrogen sulfide, halogens, phosphorus, isocyanates, strong alkalis and amines (American Conference of Governmental Industrial Hygienists, 1991)... [Pg.319]

Acylation reactions can be carried out by the action of acid anhydrides [66, 67], chloroanhydrides [47, 61], isocyanates [68], isothiocyanates [68, 69] and thioamides [70]. It was shown that the reaction of aziridinyl ketone 49 with chloroacetyl chloride 50 in the presence of Et3N [61] leads to the formation of A-acyl derivative 51, whereas the alkylation product was not isolated. [Pg.11]

Pyridopyrimidine systems may also be accessed by in situ generation of pyridylisocyanates <2003TL2745>. Treatment of 2,3-pyridinccarboxylic anhydride with methanol leads to the formation of 2-(methoxycarbonyl)nicotinic acid that undergoes Curtius rearrangement on conversion to the 3-acyl azide with sodium azide and ethyl chloro-formate. Condensation of the resulting isocyanate with a series of amino acids leads to the synthesis of pyrido[3,2- T pyrimidines in good to excellent yield (Scheme 19). [Pg.130]

Hydroxythieno[2,3-d]pyrimidines 19d were acylated at the N —OH group with acyl chlorides, acid anhydrides, or isocyanates [81JAP(K)8389, 81JAP(K)53681, 81JAP(K)56389, 81JAP(K)59778],... [Pg.223]


See other pages where ISOCYANIC ACID, ANHYDRIDE WITH is mentioned: [Pg.16]    [Pg.9]    [Pg.16]    [Pg.9]    [Pg.258]    [Pg.1059]    [Pg.135]    [Pg.286]    [Pg.24]    [Pg.234]    [Pg.423]    [Pg.592]    [Pg.595]    [Pg.598]    [Pg.15]    [Pg.101]    [Pg.327]    [Pg.643]    [Pg.106]    [Pg.633]    [Pg.214]    [Pg.182]    [Pg.277]   


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Isocyanates anhydrides

Isocyanates isocyanic acid

Isocyanic acid

With anhydrides

With isocyanates

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