Oximes phenols

Sterically hindered phenols react with nitric oxide under basic conditions to give either cyclohexadienone diazenium diolates or oximates. Phenols with 2,6-di-tert-butyl and 4-methyl (butylated hydroxytoluene, BHT), 4-ethyl or 4-methoxymethyl substituents yield the corresponding 2,6-di-tert-butyl-2,5-cyclohexadienone-4-alkyl-4-diazenium diolate salts (equation 58)". ... 

One-part polyurethane adhesives can also correspond to prepolymers with isocyanate functions blocked reversibly (due to reaction with oximes, phenols, etc.). The isocyanate groups are then regenerated, either by heating to a more or less high temperature, or by substitution of the blocking agent by a diol (oligomer, at least partly) (O Fig. 14.18). 

Compounds containing one or more —OH or —SH groups, such as water, alcohols, phenols, oximes, hydrogen sulphide and thiols. 

Dilute sodium hydroxide solution. Carboxylic acids (RCOOH), sulphonic acids (RSO3H), phenols (ArOH), thiophenols (ArSH), mer-captans (RSH), imides (RCONHCOR), aryl sulphonamides (AxSOjNHj), arylsulphonyl derivatives of primary amines (AxSOjNHR), oximes (RCH=NOH), primary and secondary nitro compounds (RCH=NOOH and RjC=NOOH-oci forms), and some enols (e.g., of 1 3-diketones... 

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

Carbamate Insecticides. These are stmcturaUy optimi2ed derivatives of the unique plant alkaloid physostigmine [57-47-6] a cholinergic dmg isolated in 1864 from Phjsostigma venenosum (see Alkaloids) (17,24,35—39). The carbamates maybe considered synthetic derivatives of the synaptic neurotransmitter acetylcholine, with very low turnover numbers. The A/,A/-dimethylcarbamates of heterocycHc enols (36) and the Ai-methylcarbamates of a variety of substituted phenols (35) with a wide range of insecticidal activity were described in 1954 (35). The latter are the most widely used carbamate insecticides, and the A/-methylcatbamates of oximes have subsequentiy been found to be effective systemic insecticides. 

Developments in aliphatic isocyanates include the synthesis of polymeric aliphatic isocyanates and masked or blocked diisocyanates for appflcafions in which volatility or reactivity ate of concern. Polymeric aliphatic isocyanates ate made by copolymerizing methacrylic acid derivatives, such as 2-isocyanatoethyl methacrylate, and styrene [100-42-5] (100). Blocked isocyanates ate prepared via the reaction of the isocyanate with an active hydrogen compound, such as S-caprolactam, phenol [108-95-2] or acetone oxime. 

Caprolactam [105-60-2] (2-oxohexamethyleiiiiriiQe, liexaliydro-2J -a2epin-2-one) is one of the most widely used chemical intermediates. However, almost all of the aimual production of 3.0 x 10 t is consumed as the monomer for nylon-6 fibers and plastics (see Fibers survey Polyamides, plastics). Cyclohexanone, which is the most common organic precursor of caprolactam, is made from benzene by either phenol hydrogenation or cyclohexane oxidation (see Cyclohexanoland cyclohexanone). Reaction with ammonia-derived hydroxjlamine forms cyclohexanone oxime, which undergoes molecular rearrangement to the seven-membered ring S-caprolactam. 

Dutch State Mines (Stamicarbon). Vapor-phase, catalytic hydrogenation of phenol to cyclohexanone over palladium on alumina, Hcensed by Stamicarbon, the engineering subsidiary of DSM, gives a 95% yield at high conversion plus an additional 3% by dehydrogenation of coproduct cyclohexanol over a copper catalyst. Cyclohexane oxidation, an alternative route to cyclohexanone, is used in the United States and in Asia by DSM. A cyclohexane vapor-cloud explosion occurred in 1975 at a co-owned DSM plant in Flixborough, UK (12) the plant was rebuilt but later closed. In addition to the conventional Raschig process for hydroxylamine, DSM has developed a hydroxylamine phosphate—oxime (HPO) process for cyclohexanone oxime no by-product ammonium sulfate is produced. Catalytic ammonia oxidation is followed by absorption of NO in a buffered aqueous phosphoric acid... 

Cyclohexanone purity is most readily deteanined by gas-Hquid chromatography over DC-710 or carbowax 20M-on-chromosorb. Impurities such as cyclohexane, ben2ene, cyclohexanol, and phenol do not interfere. In the absence of other carbonyl compounds cyclohexanone may be deterrnined by treatment with hydroxylamine hydrochloride, which forms the oxime, as follows ... 

A -Methylation of the NH of heterocycles using 1 is also known as exemplified by the methylation of indole/ The interesting mechanism is delineated below. O-methylation of weak acids such as phenols, carboxylic acids and oximes as well as 5-methylation such as A -phenylisorhodanine, certain thioketones, and dithiocarboxylic acids have also been reported." ... 

It yields a phenylurethane melting at 41°, a semi-carbazone melting at 219° to 220°, and an oxime melting at 125°. The OH group appears to possess alcoholic as well as phenolic functions, forming acetic and benzoic esters, as well as direct combinations with alkalis. 

Reductive alkylations have been carried out successfully with compounds that are not carbonyls or amines, but which are transformed during the hydrogenation to suitable functions. Azides, azo, hydrazo, nitro and nitroso compounds, oximes, pyridines, and hydroxylamines serve as amines phenols, acetals, ketals, or hydrazones serve as carbonyls 6,7,8,9,12,17,24,41,42,58). Alkylations using masked functions have been successful at times when use of unmasked functions have failed (2). In a synthesis leading to methoxatin, a key... 

The cyclopentadienyl groups are readily displaced by protic acids HX (e.g., alcohols, phenols, thiols, and oximes), providing a convenient route to other Sn(II) compounds (320-323). 

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