Chemistry of hydrocarbon compounds – Aromatic compound synthesis – Having alkenyl moiety – e.g. – styrene – etc.
Patent
1996-01-23
1998-04-28
Yildirim, Bekir L.
Chemistry of hydrocarbon compounds
Aromatic compound synthesis
Having alkenyl moiety, e.g., styrene, etc.
585435, 585 2, 585 3, 585 4, 585 5, 585832, 203 9, 208 48AA, C07C 5333, C07C 720
Patent
active
057446725
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This application is a 371 of PCT/IB 94/00240, filed on Jul. 18, 1994. The invention relates to the chemical industry, more specifically to the prevention of spontaneous polymerization of vinyl aromatic compounds during a production process. Typical of such vinyl aromatic compounds are styrene, alpha-methylstyrene, vinyltoluene and divinylbenzene. Methyl vinylpyridine is also contemplated as broadly encompassed by the vinyl aromatic terminology. Styrene will be referred to as illustrative but the foregoing compounds are understood to be included.
In the process of isolating styrene from the products of dehydrogenation of ethylbenzene, at the stage of rectification, there occurs the spontaneous polymerization of styrene monomer at high temperature. This polymerized styrene coats and/or chokes equipment, which in turn reduces heat transfer efficiency of the facilities and sometimes causes a halt of production for unscheduled cleanout. In order to avoid undesirable styrene polymerization, use is made of inhibitors.
Known in the art are methods for inhibiting the polymerization of styrene at elevated temperatures using a mixture of p-quinone dioxime with hydroquinone (USSR Inventors's Certificate 257496, 1968) or p-nitrophenol (USSR Inventor's Certificate 441263, 1972). However, they display low solubility in aromatic hydrocarbons, which result in clogging of transmission pipe lines, the trays and boilers of columns. The use of p-quinone dioxime suspensions calls for special, power consuming equipment and, most importantly, said p-quinone dioxime is inflammable and its dust-air mixtures are dangerously explosive.
A close piece of prior art discloses a method of inhibiting the polymerization of styrene with a mixture of 3,5-di-tert-butyl-4-hydroxy-N,N-dimethylbenzyl amine and aliphatic carboxylic acids (USSR Inventor's Certificate 819078, 1978).
The mixture of 3,5-di-tert-butyl-4-hydroxy-N,N-dimethylbenzyl amine with carboxylic acids in USSR Inventor's Certificate 819078, 1978 is substantially an effective polymerization inhibitor for styrene at temperatures of about 120.degree. C. with the components thereof exhibiting: good solubility in aromatic hydrocarbons; being nontoxic; fireproof; explosionproof and inert toward the monomer. However, the doses of said inhibitor are big enough (0.5 to 0.22% by weight) that it has been established that a considerable portion of the inhibitor per se is not spent over the residence staying time in the column. This results in residual inhibitor being present in the effluent or waste from the process, and thus, there is a need to improve on said prior art inhibitor.
It is an object of the invention to improve efficiency and reduce the amount of the inhibitor consumed.
BRIEF DESCRIPTION OF THE INVENTION
This invention discloses a process for inhibiting the polymerization of a vinyl aromatic compound comprising adding to the vinyl aromatic compound an effective amount of an inhibitor system comprising: a) 3,5-di-tert-butyl-4-hydroxy-N,N-dimethylbenzyl amine; b) an acid component selected from the group consisting of carboxylic acids, synthetic fatty acids, anhydrides of an organic acid, and inorganic acids; and c) air, wherein a), b) and c) are present in the weight ratio of 1:1 to 0.05:0.05 to 15. A preferred method for inhibiting the polymerization of styrene is with a mixture of 3,5-Di-tert-buty-4-hydroxy-N,N-dimethylbenzyl amine and carboxylic acids or anhydrides thereof, in the presence of air or oxygen. The weight ratio of said 3,5-Di-tert-butyl-hydroxy-N,N-dimethylbenzyl amine, carboxylic acid (carboxylic acid anhydride) and the air (oxygen) is 1:1-0.05:0.05-15, respectively.
DETAILED DESCRIPTION OF THE INVENTION
The technological advancement in the art of styrene production is achieved by using the claimed method for inhibiting the polymerization of styrene by adding the inhibitor solution of a mixture of 3,5-di-tert-butyl-4hydroxy-,N-dimethylbenzyl amine and carboxylic acid or an anhydride of said carboxylic acid simultaneously with a
REFERENCES:
patent: 5488192 (1996-01-01), Kourbatov et al.
Derwent's abstract, No. 87-340816/48, week 8748, Abstract of SU, 1305-153 (Batalin O E), 23 Apr. 1987.
Derwent's abstract, No. 5276 E/03, week 8203, Abstract Of Su, 819-078 (Vernov P A), 7 Apr. 1981.
STN International, File CA, Chemical Abstracts, vol. 102, No. 20, 20 May 1985 (Columbus, Ohio, US), Volkov, R.N. et al: "Inhibiting polymerization of vinylaromatic monomers," abstract No. 167348, & Otkrytiya, Izobret. 1984, (48), 210.
STN International, file CA, Chemical Abstracts, vol. 100, No. 22, 28 May 1984 (Columbus, Ohio, US), Kurbatov, V.A. et al: "Inhibition of oxidative polymerization of styrene by phenols. Self-fluctuating conditions," abstract No. 175381, & Vysokomol. Soedin., Ser. A (1984), 26(3), 541-6.
Boreyko Nataljya Pavlovna
Kourbatov Vladimir Anatolievich
Liakumovich Alexandr Grigorievich
Zouev Valerii Pavlovich
LandOfFree
Method for inhibiting the polymerization of vinyl aromatics does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for inhibiting the polymerization of vinyl aromatics, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for inhibiting the polymerization of vinyl aromatics will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1533467