Bases Potassium hydroxide

Bases Potassium hydroxide, polyethyleneimine, polypropyleneimine, N, N -b/s-L-methylhepty l-p-phenylenediamine, sodium metanilate, THEED (tetrahydroxyethylenediamine) These modifiers will act as subtractive agents for acidic components in the sample polypropyleneimine will selectively abstract aldehydes, polyethyleneimine will abstract ketones... 

The direct synthesis of a.g-unsaturated nitriles can be accomplished by treating the appropriate carbonyl compound with potassium hydroxide in acetonitrile.8 In order for direct condensation to succeed, acetonitrile must be deprotonated by the relatively weak base potassium hydroxide and the carbanion thus formed must add to the carbonyl. The cyanohydrin is presumably... 

Reinecke compared the effects of two bases, potassium hydroxide and triethylamine, on the dehalogenation of dichlormethyl-substituted cyclohexanones over 10% Pd-C in methanol.207 Dehalogenation of 4-dichloromethyl-4-methylcyclohexanone proceeded smoothly in the presence of potassium hydroxide to give primarily 4,4-di-methylcyclohexanone, while in the presence of triethylamine, in addition to 4,4-dimethylcyclohexanone and a little partially dechlorinated material, an approximately equal amount of stereoisomeric 4-dichloromethyl-4-methylcyclohexanols was isolated. Since the dichloro alcohols were rapidly dehalgenated to 4,4-dimethylcyclo-hexanol in the presence of potassium hydroxide, the inertia of the chlorine atoms in the dichloro alcohols was considered to be due to the presence of triethylamine (eq. 13.112). 

Total Acid Number (TAN) A property of crude oil. The acid number expresses the amount of base (potassium hydroxide) that will react with a given amount of crude oil in a standardized titration procedure. A large acid number indicates a high concentration of acids in the oil, usually including natural surfactant precursors. 

One of the many important differences between phosphorus and nitrogen chemistry is the relative strengths of their bonds to hydrogen. The relatively weak P—H bond means that this functionality can be added across a wide variety of unsaturated molecules (alkenes, alkynes, carbonyls) and hence this represents an excellent method for preparing tertiary phosphines. The addition of P 11 compounds to C=0 and C=N has been described in detail by Gilheany and Mitchell.2 The reaction can be catalyzed by base (potassium hydroxide, butyllithium), acid (HC1, carboxylic acids, sulfonic acids, boron trifluoride), free radical (uv, organic peroxides, AIBN) or metal (simple metal salts, late transition-metal complexes). In some circumstances no catalyst is required at all for P 11 additions to proceed.60... 

The reaction is sensitive to steric hinderance. Aromatic ketones are reduced to hydrocarbons. Unsaturated ketones are fully reduced and with no selectivity. Complexes of the type Ir(Chel)(CH2=CH2)2Cl, with Chel = 2,2 -bipyridine or phenantholine derivatives, behave as catalyst precursors for hydrogen transfer from isopropanol to ketones and Schiff bases. Potassium hydroxide is required as cocatalyst to convert the isopropanol coordinated to the Ir(I) ion, in the neutral isopropoxy derivative. Enolates that are present would act as inhibitors when coordinated to the cationic derivative. Ethylene complexes are better precursors than the corresponding cyclooctadiene derivatives, because they are activated more easily and more completely, and they show high catalytic activity. The most active complexes is the 3,4,7,8-Me4 phen derivative, which, at 83°C, gives turnovers of up to 2850 cycles/min. Reduction of 4-r-butylcyclohexanone affords 97% of the tra/u-alcohol. 

Olefins that are activated by electron-attracting substituents add phosphine and primary or secondary phosphines extremely readily in the presence of strong bases (potassium hydroxide or organic bases such as heptamethyl-biguanide). 

Contact with water. This is commonly the case with the corrosive solids, such as the inorganic base potassium hydroxide and the organic crotonic acid. As solids, these do not have any available hydrogen or hydroxyl ions but easily form solutions in contact with water or moisture fi om the air or from skin, eyes, lung tissues, etc. 

The hydroxides M (OH)2 are generally less soluble and are of lower base strength. The Group I hydroxides are almost unique in possessing good solubility—most metal hydroxides are insoluble or sparingly soluble hence sodium hydroxide and, to a lesser extent potassium hydroxide, are widely used as sources of the hydroxide ion OH" both in the laboratory and on a large scale. 

Upon warming with 10-20 per cent, sodium or potassium hydroxide solution, no ammonia is evolved (distinction from primary amides). The base, however, is usually liberated upon fusion with soda lime (see experimental details in Section IV,175) and at the same time the acyl group yields a hydrocarbon. Thus benz-p-toluidide affords p-tolu-idine and benzene. 

Similarly sodium methoxide (NaOCHj) is a suitable base and is used m methyl alco hoi Potassium hydroxide m ethyl alcohol is another base-solvent combination often employed m the dehydrohalogenation of alkyl halides Potassium tert butoxide [K0C(CH3)3] is the preferred base when the alkyl halide is primary it is used m either tert butyl alcohol or dimethyl sulfoxide as solvent... 

Maleic Anhydride. The ACGIH threshold limit value in air for maleic anhydride is 0.25 ppm and the OSHA permissible exposure level (PEL) is also 0.25 ppm (181). Maleic anhydride is a corrosive irritant to eyes, skin, and mucous membranes. Pulmonary edema (collection of fluid in the lungs) can result from airborne exposure. Skin contact should be avoided by the use of mbber gloves. Dust respirators should be used when maleic anhydride dust is present. Maleic anhydride is combustible when exposed to heat or flame and can react vigorously on contact with oxidizers. The material reacts exothermically with water or steam. Violent decompositions of maleic anhydride can be catalyzed at high temperature by strong bases (sodium hydroxide, potassium hydroxide, calcium hydroxide, alkaU metals, and amines). Precaution should be taken during the manufacture and use of maleic anhydride to minimize the presence of basic materials. 

Manganese Hydroxide. Manganese hydroxide [18933-05-6] is a weaMy amphoteric base having low solubihty in water. Mn(OH)2 crystals are reported to be almost pure white and darken on exposure to air. Manganese dihydroxide occurs in nature as the mineral pyrochroite and can also be prepared synthetically by reaction of manganese chloride and potassium hydroxide that is scmpulously free of oxygen. The entire reaction is conducted under reducing conditions (36). 

Methyl-l-Pen ten e. This olefin is produced commercially by dimeriza tion of propylene in the presence of potassium-based catalysts at 150—160°C and - 10 MPa. Commercial processes utilize several catalysts, such as sodium-promoted potassium carbonate and sodium- and alurninum-promoted potassium hydroxide (12—14) in a fixed-bed reactor. The reaction produces a mixture of C olefins containing 80—85% of 4-methyl- 1-pentene. 

Nucleophilic Substitution Route. Commercial synthesis of poly(arylethersulfone)s is accompHshed almost exclusively via the nucleophilic substitution polycondensation route. This synthesis route, discovered at Union Carbide in the early 1960s (3,4), involves reaction of the bisphenol of choice with 4,4 -dichlorodiphenylsulfone in a dipolar aprotic solvent in the presence of an alkaUbase. Examples of dipolar aprotic solvents include A/-methyl-2-pyrrohdinone (NMP), dimethyl acetamide (DMAc), sulfolane, and dimethyl sulfoxide (DMSO). Examples of suitable bases are sodium hydroxide, potassium hydroxide, and potassium carbonate. In the case of polysulfone (PSE) synthesis, the reaction is a two-step process in which the dialkah metal salt of bisphenol A (1) is first formed in situ from bisphenol A [80-05-7] by reaction with the base (eg, two molar equivalents of NaOH),... 

An alternative synthesis route for PES involves the partial hydrolysis of dichlorodiphenyl sulfone (2) with base to produce 4-chloro-4 -hydroxydiphenylsulfone [7402-67-7] (3) followed by the polycondensation of this difimctional monomer in the presence of potassium hydroxide or potassium carbonate (7). 

Typical values for mf n are 0.5 to 2.5. Gommercially used bases include sodium hydroxide, potassium hydroxide, calcium hydroxide (lime), magnesium hydroxide, sodium carbonate, sodium alurninate, calcium carbonate, or various mixtures. For certain appHcations, PAG can be made from waste grades of aluminum chloride [7446-70-0] such as spent catalyst solutions from Friedel-Grafts synthesis (see Friedel-Grafts reaction). 

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

Vinyl chloride reacts with sulfides, thiols, alcohols, and oximes in basic media. Reaction with hydrated sodium sulfide [1313-82-2] in a mixture of dimethyl sulfoxide [67-68-5] (DMSO) and potassium hydroxide [1310-58-3], KOH, yields divinyl sulfide [627-51-0] and sulfur-containing heterocycles (27). Various vinyl sulfides can be obtained by reacting vinyl chloride with thiols in the presence of base (28). Vinyl ethers are produced in similar fashion, from the reaction of vinyl chloride with alcohols in the presence of a strong base (29,30). A variety of pyrroles and indoles have also been prepared by reacting vinyl chloride with different ketoximes or oximes in a mixture of DMSO and KOH (31). 

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