P-Tert butyl catechol

Procedure For Determining Hydro quin one and/or p-Tert-Butyl Catechol In Castable PBX Raw Materials , NAVWEPS 8236 (1964) 37) OX. 

A 500-ml. three-necked round-bottomed flask is attached to a 250-ml. dropping funnel and a total-condensation variable takeoff fractionating column with a 20 by 1.2 cm. section packed with glass helices (Note 1). The fractionating column is fitted to a 500-ml. receiving flask. In the reaction flask are placed 12.5 g. of powdered fused potassium acid sulfate and 0.05 g. of p-tert.-butyl-catechol. The flask is immersed in an oil bath maintained at 220-230°, and 145 g. (0.925 mole) of m-chlorophenylmethylcar-binol (p. 28) and 0.05 g. of -(erL-butylcatechol (Note 2) are placed in the dropping funnel. The system is evacuated to a... 

Styrene,purity > 99% (Fluka) stabilized with 0.005% of tert-butyl catechol was purified by treating with IN Sodium hydroxide repeatedly and washed with distilled water.Styrene is dried for several hours with MgS04 and finally distilled under reduced pressure(2). Phenolphthalein (CDH India) Bromothymol blue (CDH India), p-Nitroaniline (CDH India), 2,4-Dinitroaniline (CDH India) and 4-Chloro 2-nitroaniline ( Lancaster UK), p-tert-Butyl catechol (National Chemicals India) were used without further purification. 

Determination of TBC in Styrene To determine the amount of inhibitor p-tert butyl catechol (TBC) present, the styrene monomer is extracted with aqueous NaOH and the aqueous layer containing the TBC as the coloured quinone is separated and the colour measured spectrophotmetrically at a wavelength of 485 run using NaOH of 1.0 N solution as a reference standeud. ASTM Method (D2120-82) is used for determining concentration of inhibitor, in styrene monomer. This method covers the measurement of the amount of residual TBC iii styrene monomer in the range from 0-100 ppm. 

Polyfunctional aziridine hardeners and polyfunctional acrylates Urethane resins Cyclohexanone resin p-tert-Butyl catechol Unsaturated polyester resin... 

Monomers are generally purified continuously to remove chain terminators such as water, oxygen, stabilisers like p-tert butyl catechol and polar compounds. This is generally done using alumina beds, or by using distillation columns. 

This spectrophotometric method determines inhibitors such as hydroquinone, p-tert butyl catechol or p-methoxy phenol in amounts down to 10 ppm in styrene monomer. 

Hindered phenolic types of monomer stabilizers (eg. p-methoxy phenol and p tert butyl catechol) do not interfere in the described procedure. 

The sample of styrene monomer is shaken with sodium hydroxide solution in the presence of air. The inhibitor is oxidised to form a red coloured quinoid compound which extracts into the sodium hydroxide phase. The colour intensity of the complex is measured using a spectrophotometer at a wavelength of 480 nm and hence the amount of p-tert butyl catechol present in the styrene monomer may be read off directly from a prepared calibration graph. 

Pipette 1, 2, 3, 4, 5 and 10 cm of a 100 ppm solution of p-tert butyl catechol dissolved in purified styrene monomer, into a separate 500 cm volumetric flasks and dilute to the marie with purified monomer. Mix the solutions thoroughly and proceed as described under Method. Plot the optical density values obtained against tl concentration of p-tert butyl catechol (ppm) present in the 500 cm dilutions. 

From the optical density obtained read off the p-tert butyl catechol concentration present in the 500 cm styrene monomer sample, directly from the calibration grai. ... 

This method is capable of determining down to 0.1 ppm p-tert butyl catechol inhibitor in styrene monomer with an accuracy of 5%. 

Determination of hydroquinone, p-tert-butyl catechol and p-methoxy... 

Determination of p-tert-butyl catechol inhibitor in styrene monomer. 

Components of technical pentachlorophenol Mixture of eugenol (282 m/i) and isoeugenol (254 m/i) p-Tert-butyl catechol at 279 m/i in water after weathering off the butadiene in which it serves as an oxidation inhibitor [ ]. 

METHYL STYRENE or 3-METHYL STYRENE or 4-METHYL STYRENE or m-METHYL STYRENE or p-METHYL STYRENE mixed Isomers (25013-15-4) C,H,o Flammable liquid. Forms explosive mixture with air (flash point 125°F/51°C). An inhibitor, usually 10 to 50 ppm of tert-butyl catechol, must be present in adequate concentrations to avoid explosive polymerization. Violent reaction with strong oxidizers, strong acids, peroxides and hydroperoxides. Incompatible with catalysts for vinyl or ionic polymers aluminum, aliuninum chloride, ammonia, aliphatic amines, alkanolamines, caustics, copper, halogens, iron chloride, metal salts (e.g., chlorides, iodides, sulfates, nitrates). The uninhibited monomer vapor may block vents and confined spaces by, forming a solid polymer material. On small fires, use dry chemical powder (such as Purple-K-Powder), foam, or CO extinguishers. a-METHYL STYRENE (98-83-9) C,H, Flammable liquid. Forms explosive mixture with air [explosion limits in air (vol %) 0.9 to 6.1 flashpoint 129°F/54°C autoignition temp 1066°F/574°C Fire Rating 2]. Easily polymerizable. Unless inhibited, forms unstable peroxides. Reacts with heat and/or lack of appropriate inhibitor concentration. Reacts with catalysts for vinyl or ionic polymerization, such as aluminum, iron chloride or 2,5-dimethyl-2,5-di(ieri-butylperoxy)hexane. Violent reaction with... 

METHYL STYRENE or 4-METHYL STYRENE or m-METHYL STYRENE or p-METHYL STYRENE, MIXED ISOMERS (25013-15-4) Forms explosive mixture with air (flash point 125 F/51°C). Inhibitor (usually 10-50 ppm of tert-butyl catechol) must be present in adequate concentrations to avoid explosive polymerization. Violent reaction with strong oxidizers, strong acids, peroxides. Incompatible with aluminum chloride, ammonia, aliphatic amines, alkanolamines, caustics, metal salts (e.g., chlorides, iodides, sulfates, nitrates). The uninhibited monomer vapor may block vents and confined spaces by forming a solid polymer material. 

Stabilization of the polymeric and monomeric components is required to avoid premature radical polymer formation of UP resin dissolved in styrene by heat, light, or metallic initiators. Insufficient stabilization causes an increase in viscosity that makes further processing impossible. Quinones and phenols in concentrations < 500 ppm are proven stabilizers for unsaturated polyester. The most important examples are hydroquinone, p-benzoquinone, tert-butyl-brenzcatechol and 2,6-di-tert-butyl-p-cresol [574]. For styrene, stabilization with 25 ppm p-tert-butyl-brenz-catechol is required [575]. Slight yellowing caused by the stabilizers is possible appropriate brighteners are recommended for optically demanding applications. 

Breslow s P-cyclodextrine ribonuclease model system represents one of the best examples concerning the construction of small enzyme-like molecules [33]. Breslow functionalized the P-cyclodextrine with two imidazole moieties (Figure 10.1). Selectively, catechol cyclic phosphate carrying a 4-tert-butyl group (Figure 10.1a) binds into the cavity of the catalyst (Figure 10. lb) in water solution, and is then hydrolyzed by the... 

The redox potentials for several quionones (Q 3,5-di-tert-butyl-o-quinone, o-benzoquinone, p-benzoquinone, and tetrafluoro-o-benzoquinone), their semi-quinone anion radicals (SQ- -) and their fully reduced forms [catechols (H2Cat) and catechol anions (HCat-)] in four aprotic solvents [acetronitrile (AN), di-methylformamide (DMF), dimethylacetaminde (DMA), and dimethyl sulfoxide (Me O)] are summarized in Table 12.2.12... 

Hogan DJ, Tanglertsampan C (1992) The less common occupational dermatoses. Occup Med 7 385-401 Horio T (1977) Depigmentation due to para tertiary butyl catechol. Int Arch Occup Environ Health 39 127-133 James 0, Mayes R, Stevenson C (1977) Occupational vitiligo induced by p-tert-butylphenol, a systemic disease Lancet 2 1217-1219... 

Fig. 19. Absorption of oxygen in the oxidation of pure polypropylene (1) and stabilized by di-tert-butyl-p-cresyl disulfide and pyro-catechol phosphite naphthol (2) (3) shows the drop in viscosity in the latter case.

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