Nonisolated intermediate

Of these producers, Atochem, Degussa, and Daicel are reported to be in the merchant acrolein business. Union Carbide suppHes only the acrolein derivative markets. Rhc ne-Poulenc also produces acrolein, primarily as a nonisolated intermediate to make methionine. A number of other small scale plants are located worldwide which also produce acrolein as an intermediate to make methionine. 

Cyclic carbonylylid.es 173 react with Z-methoxybutenyne according to the [2+3]-eyeloaddition seheme to form the furan derivatives 175 via nonisolable intermediate 174 (85CB785). 

Azabicyclo[4.2.0]octatriene systems (e.g. 8), formed as nonisolable intermediates during the photochemical addition of benzonitrile or 1-naphthonitriles to phenols,16 -19 isomerize to 2-hydroxyazocines which exist predominantly as the lactam tautomers. 

The ten-membered cyclic amine 106 was efficiently prepared from quionolizidine derivative 105 by methylation to a nonisolated intermediate followed by an olefin-forming desulfonylation reaction induced by treatment with sodium amalgam (Scheme 11) <20010L2957>. 

The cycloaddition of nitrile oxide 235 to the 4-iminobenzopyran-2-one 236 gave the fully conjugated 1,2,4-oxadiazole 238 directly, a reaction that most likely proceeds via loss of methanol from the intermediate 237 (Scheme 36) <1996JHC967>. Similarly, nitrile oxide 239 reacted with imine 240 to give the 1,2,4-oxadiazole 242 via the nonisolable intermediate 241 <2002PJC1137>. 

This index lists the heterocyclic parent ring systems and has been compiled from the occurrences of those systems and their derivatives in Volumes 1-15 in the text, tables, equations, and schemes. Heterocycles have been included when they occur as a starting material, isolable intermediate, or a product, but not when they are reported as a nonisolable intermediate or a solvent. 

REACH is very wide in its scope covering aU substances (see definition of substances in Section 2.4.1) whether manufactured, imported, used as intermediates or placed on the market, either on their own, in preparations or in articles, unless they are radioactive, subject to customs supervision, or are nonisolated intermediates. Waste is specifically exempted. Food is not subject to REACH, as it is not a substance, preparation, or article. Member States may exempt substances used in the interests of defense. Other substances are exempted from parts of REACH, where other equivalent legislation applies for fiufher details refer EU (2006i). 

An interesting variation is the reaction of a diacetylene on cpCo(diene) systems [Eq.(24)J. 1,7-Octadiyne Initially undergoes an intramolecular process to give a nonisolable intermediate containing a cyclohexane ring. 

An example of synthesis A is that of 5-methyl-1,2,4-triazolo[l,5-a] pyrimidin-7-on (MOT) (3) by Bulow and Haas (09CB4638) given in Scheme 1. This reaction is a pyrimidine synthesis The C3-synthon condenses with a N—C—N moiety, which is a part of an AT. Apparently the reaction passes through the nonisolable intermediate 2 (Section II,A,2). 

Phenylbenspate, [93-99-2], CH.COOCJ f, mp, 70—71°C bp, 314°C at 101.3 kPa. This has been suggested as an antioxidant (qv) for certain high temperature lubricants (41). Phenyl benzoate exists as a nonisolated intermediate in the production of phenol from benzoic acid. 

The synthesis of the (i) 4-hydroxy-6-methoxytetrahydrofuro[2,3-6]-benzofuran ring (116), a degradation product of natural substances of the sterigmatocystin series, is similar,318 as is the synthesis of the dihydro derivative (117) from the o-acetylated acetaldehyde (118), a nonisolated intermediate which is ring-closed to 119 and then heated in toluene to give 117. The last is the starting point for the synthesis of aflatoxin M4 (49).153... 

Compound 408 with 3% KOH/ethanol forms benzofuran 409,853 with decarboxylation of the nonisolated intermediate. Alkaline degradation (KOH/ethanol) of compounds 410 leads to 2-phenylbenzofuran-3-carboxylic acids (411, R = H), then, by methylation, to compounds 411 (R = Me)398 or by decarboxylation to 2-phenylbenzofuran... 

The isolation of stable vinylidene complexes and elucidation of many of their reactions have given substance to speculations concerning their intermediacy in many reactions. Indeed, the reactions of many alkynes with a series of platinum(II) complexes were explained several years ago by considering the formation of metal-stabilized carbonium ions as nonisolable intermediates (10). Summarized below are several reactions that may reasonably be assumed to proceed via vinylidene complexes. 

The formation of compound 175 could be rationalized in terms of an unprecedented domino allene amidation/intramolecular Heck-type reaction. Compound 176 must be the nonisolable intermediate. A likely mechanism for 176 should involve a (ji-allyl)palladium intermediate. The allene-palladium complex 177 is formed initially and suffers a nucleophilic attack by the bromide to produce a cr-allylpalladium intermediate, which rapidly equilibrates to the corresponding (ji-allyl)palladium intermediate 178. Then, an intramolecular amidation reaction on the (ji-allyl)palladium complex must account for intermediate 176 formation. Compound 176 evolves to tricycle 175 via a Heck-type-coupling reaction. The alkenylpalladium intermediate 179, generated in the 7-exo-dig cyclization of bro-moenyne 176, was trapped by the bromide anion to yield the fused tricycle 175 (Scheme 62). Thus, the same catalytic system is able to promote two different, but sequential catalytic cycles. 

The results of this reaction changed when the conditions were slightly different. Other authors have reported that with MP in refluxing benzene for 2 days, the polymerization of 2-vinylthiophene 59 took place quite rapidly and no adducts could be isolated (89JHC397). However, when a neat 1 3 mixture of 59 and MP was heated in a sealed tube at 110° for 4 days, compound 69 was isolated in 70% yield. One of the striking contrasts of this reaction, in comparison with the addition of MP to l-methyl-2-vinylpyrrole 20a, is the different regioselectivity of the reaction between the disymmetric dienophile MP with the nonisolated intermediates. In this latter case the indole 27 was isolated. 

In the past, BCME was used for crosslinking of cellulose, preparation of styrene and other polymers, surface treatment of vulcanized rubber to increase adhesion, and in the manufacture of flameretardant fabrics (EPA 1980a). These applications have been discontinued, and no uses of BCME other than as a nonisolated intermediate were identified. 

Generally the azolidine derivatives of structures 14-16 are less studied than other classes of (oxa/thia)-2-azoles, either because of their thermal instability or because of the difficulty in their preparation. Some of them are isolable compounds, others are nonisolable intermediates or reversibly dissociate to their starting precursors. Several examples dealing with thermal stability of certain 1,4,2-dioxazolidines, 3-imino-l,4,2-dioxazolidines, as well as 1,4,2-oxathizo-lidine derivatives, have been reported <1996CHEC-II(4)519>. Some new data are given below. 

Although the 1,4,2-oxathiazolidine derivatives 16 (X = O Y = S) are usually nonisolable intermediates of reactions between nitrones and thiocarbonyl compounds, in some instances a cycloaddition/cycloreversion equilibrium is established with steric hindrance influencing its position. This is the case for the kinetically stable... 

For this reaction, we proposed a mechanism involving a nonisolable intermediate of pentacarbony carbamoyImanganese(+I) Mn(CO)5CONH2 (104). The second involves the reactions of CO with solutions of KNH2 in liquid NH3 (106). In the presence of a large excess of CO, formamide... 

Production or importation of the listed chemical solely as an impurity, a nonisolated intermediate, and under certain circumstances as a by-product. 

Substances not on the Inventory or are not otherwise excluded or exempt are considered new and are subject to a premanufacture notice (PMN). Examples of exclusions would include mixtures, substances subject to another statute, impurities, by-products and nonisolated intermediates. Additional exemptions also include test marketing products, low volume products, polymer exemptions, LoREX (low release and exposure exemption), and R D substances. By statute, chemical manufacturers must notify the Agency at least 90 days before manufacturing a chemical substance that is not listed on the TSCA Chemical Substance Inventory. However, TSCA does not empower the US EPA to require routine testing of new chemicals to permit a valid evaluation of the potential risks. This has been a limitation in the overall effectiveness of the PMN process. Erequently, very little data accompanies the PMN (50% of submissions present no safety data and 90% have only an LD50 and an Ames test) however, the EPA must decide within 90 days if the submitted chemical will pose a health or environmental hazard. 

A prototype for the new cyclization reaction is the Ziegler-Hafner synthesis of azulene (J)4 by heating the fulvenoid decapentaene (/). Woodward28 was the first to argue that a thermal, electrocyclic [rr 10 s] ring-closure could be involved in this thermolytic process. Of course it seems likely that the nonisolable intermediate (2) may be formed by an intramolecular electrophilic attack of atom 10 to the electron-rich position 1 in compound (1). Indeed a distinction between the two different reaction modes is mechanistically irrelevant in this case. But only its interpretation as an electrocyclic process allows the generalization to [ir 6 s] cyclizations too. 

Consequently the formation of both these compounds can be visualized by the pathways shown on the previous page (with R changing from methoxycarbonyl to the carboxy functionalities in the final products). Direct attack of the intermediate cyclopropylmethyl cation C by water and loss of a proton leads to the nonisolated intermediate E which subsequently lactonizes as a consequence of the cis relationship of the cyclopropyl substituents. Similarly, the indirect attack of the nucleophile leads to the nonisolated hydroxy acid corresponding to F which on workup is transformed into a tetrahydrofuran derivative. 

The propensity of cyclopropylideneamines to give stable adducts with alcohols was also reflected in reactions in which the strained iminocyclopropanones were generated as nonisolable intermediates. Photolysis of 3-iminocyclobutanones 13 in alcohols resulted in decarbonylation giving 2,2,3,3-tetramethylcyclopropylideneamines 14 which were isolated as the stable alcohol adducts 15. This reaction was accompanied by the formation of an a-oxacarbene 16, which was transformed into the functionalized tetrahydrofurans 17. In an inert solvent, no photolytic decarbonylation was observed, which precluded possible isolation of the corresponding tetramethyl-cyclopropylideneamine 14. ... 

This ring-expansion of the four-membered hetero ring into a six-membered one is preceded by rupture of the B C bond and formation of nonisolable intermediate 77 followed by elimination of the z. su-propyl chloride or bromide. 

On the other hand, TPs without nitro groups (e.g., parent compound la) are able to react with resorcinol under acid conditions, the nonisolable intermediate 129 being cyclized to give oxadiazocine 130 as predicted by theoretical studies (99RCB1553). 

Triazine 4-oxides react with l-ethoxy-7V,7V-dimethylalk-l-enylamines (ketene 0,N-acetals) in two different ways. 1,2,4-Triazine 4-oxides with an unsubstituted 5-position and without a methyl group in the 6-position react with the ketene 0, TV-acetals by 1,3-dipolar cycloaddition to yield isoxazolo[2,3-ci]-l,2,4-triazines as nonisolable intermediates. 5-Methyl-... 

A-Substituted cyanamides undergo cycloaddition exclusively across the 2- and 5-position in 3-(methylsulfanyl)-5,6-bis(trifluoromethyl)-l,2,4-triazine to yield the bicyclic compound as a nonisolable intermediate. Elimination of trifluoroacetonitrile affords 1,3,5-triazincs 31 while elimination of methyl thiocyanate yields 1,2,4-triazines 32202 (see Section 2.2.1.3.). 

Inverse electron demand cycloaddition of 1,2,4,5-tetrazine with alkenes and alkynes. Inverse electron demand Diels-Alder addition has also been employed for the synthesis of pyridazines and condensed pyridazines. The reaction of olefinic and acetylenic compounds with 3,6-disubstituted 1,2,4,5-tetrazines 142 to yield substituted pyridazines 144 by the intermediacy of 143 was first reported by Carboni and Lindsey (1959JA4342). Analogous reaction of 142 with a variety of aldehydes and ketones 145 in base at room temperature proceeded smoothly to yield the corresponding pyridazines 144. Compounds 146-148 are proposed nonisolable intermediates (1979JOC629 Scheme 26). 

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