Whereas, valence bond theory suggests two stable resonance structures for the ring. Benzene was first discovered in illuminating gas, by Michael Faraday who was an English Scientist. The origin of the word Benzene was from gum benzoin which was known as an aromatic resin. Decarboxylation of Sodium Benzoate This is the laboratory method to obtain Benzene from Sodium benzoate.
In this process, Sodium benzoate and Soda lime Sodium Hydroxide, along with Calcium Oxide is heated which causes decarboxylation i. Polymerization of Ethyne To produce Benzene from Ethyne acetylene , it has to undergo cyclic polymerization.
For this, Ethyne is made to pass through a red hot tube at a temperature of K, which in turn, converts itself into Benzene. Reduction of Benzenediazonium Chloride Making Benzene from Benzene-Diazonium Chloride requires the reduction of Benzenediazonium chloride with hypophosphorous acid at room temperature, results in the formation of Benzene and the reagent will get oxidized to phosphorous. Hydrolysis of Sulfonic Acid Hydrolysis of Sulfonic acid, accompanied by superheated steam produces Benzene from sulphonic acid.
Whereas, it is soluble in organic solvents. Conditions a: Substrate 1. Conditions b: Substrate 1. Conditions c: Substrate 0. Conditions d: Substrate 0. We ultimately moved to the refining of the real lignins that extracted from a variety of woods, including pine, cedrela, poplar, willow, eucalyptus, peach, applewood and cedar, and herbaceous plant Phyllostachys pubescens.
As illustrated in Fig. For comparison, a blank experiment without catalyst was also performed using the pine lignin under the same conditions, which could not yield any low-molecular weight products Supplementary Fig.
Remarkably, the in situ refining system operated transformation of the lignin is selective, and the pine lignin, for example, could be exclusively refined into benzene product with a maximum yield of In addition to the benzene product, some intermediate products, for example 2, 6-dimethoxyphenol, 2-methoxyphenol and phenol, could be detected during the reaction Supplementary Fig. As the reaction proceeded, the above intermediates were further transformed with benzene as the only liquid product Supplementary Fig.
These overwhelming evidences point out that the HY 30 and RuW centers respectively catalyzed the reactions of the C sp2 —C sp3 and C sp2 —O bonds in sequence, and their cooperation worked effectually on the refining of the H p -hydroxyphenyl , G guaiacyl and S syringyl -derived phenylpropanol building blocks in lignin [at Notably, the yields of benzene product were not always proportional to the content of phenylpropanol structure Supplementary Table 9 , which is related to the contents of the S, G, and H units in lignin.
Specifically, the mass yield of benzene abstracted from S units is sequentially lower than those from the equivalent G and H units. In contrast, pine lignin has more G and H units Supplementary Fig. To get pure benzene, we conducted a scale-up experiment for the transformation of the pine lignin, which produced 8.
The yield of benzene was slightly reduced comparing with the normal scale experiment Supplementary Fig. Based on the experimental results, we know that the lignin-to-benzene route integrates two steps, including lignin extraction and catalytic valorization of lignin, which can not only preserve the native structure of lignin for better understanding of the genuine reactivity of lignin, but more importantly, can free the lignin transformation from the interference of the reaction of the carbohydrate in wood powder.
In the first step, lignin was extracted from wood powder by solid—liquid separation and solvent recuperation, during which the used wood powder was also recovered along with the organic solvent and then used in the continual extraction process. In the second step, the extracted lignin was fed to the catalytic reactor only with water, and exclusively converted into benzene product, where the catalyst could be recovered and reused.
Meanwhile, as the only liquid product, benzene could be quite easily separated from the system without complex procedures. The sufficiently recyclable and highly selective features of the above processes are beneficial to producing benzene economically.
From the perspective of atomic economy, the active hydrogen atoms in the lignin molecule could also be utilized successfully along with the abstraction of the benzene rings from lignin under the in situ refining strategy.
Moreover, the lignin residue obtained in the lignin conversion process can be collected and further valorized into high value-added fuel products and chemicals. Given the above advantageous features, this lignin-to-benzene route has the potential of industrial application. Full data are listed in Supplementary Table 9. Yields of benzene product provided are the averages of three experiments conducted in parallel. The formula is displayed in Supplementary Table 9.
Reaction conditions: lignin 0. Innovatively, the RuW component can not only catalyze the hydrogenolysis of the C sp2 —O bond using the active hydrogen in situ abstracted from lignin molecule, but more importantly, allow Bronsted acid sites of HY 30 zeolite to promptly deconstruct the C sp —C sp3 bonds on the local structure of lignin molecule without any precedent reductive catalytic fractionation process and competition from the hydrogenolysis of the hydroxyl group in [C sp2 —C sp3 OH ] motif.
In the scale-up experiment, 8. This in situ lignin refining strategy liberates the trapped benzene rings from the molecular structure of lignin, and paves a new way for sustainable production of benzene using lignin as the feedstock, which has great potential of practical application. In a typical preparation, ammonium metatungstate AMT 1. N 2 adsorption-desorption of the samples were measured using a Micromeritics Tristar II at liquid nitrogen temperature. The specific surface areas were calculated by using the Brunauer—Emmett—Teller model.
The pore size distribution of the sample was calculated using the Barret—Joyner—Halenda pore size model. The storage ring of BSRF was operated at 2. Using Si double-crystal monochromator, the data collection were carried out in transmission mode using ionization chamber. All spectra were collected in ambient conditions. The k 2 -weighted EXAFS spectra were obtained by subtracting the post-edge background from the overall absorption and then normalizing with respect to the edge-jump step.
The contents of supported metals on the catalysts were determined by ICP. The autoclave was sealed and purged with N 2 to remove the air at room temperature and subsequently charged with 0. The liquid was collected by a filtration process. In addition, the solvent used in the above procedures were completely recovered along with the used wood powder filter residue , and reused in the next extraction experiment. In a typical experiment, a suitable amount of reactant, catalyst, and water were loaded into the reactor.
The reactor was sealed and purged with N 2 for three times to remove the air at room temperature and subsequently charged with desired gas. Then the reactor was placed in a furnace at desired reaction temperature. After the reaction, the reactor was placed in ice water, and the gas was released, passing through the ethyl acetate. The reaction mixture in the reactor was transferred into a centrifuge tube.
Then the reactor was washed with the ethyl acetate used for the gas filtration, which was finally combined with the reaction mixture. After centrifugation, the catalyst was separated from the reaction mixture.
Biphenyl was used as the internal standard to determine the conversions of substrates, selectivities and yields of the products.
The carbon balance for the reaction of the model compounds was calculated using C aromatics balance which was given relative to the aromatic products After the reaction, the reaction mixture in the reactor was transferred into a centrifuge tube. Then the reactor was washed with ethyl acetate, which was combined with the reaction mixture. Subsequently, the reaction mixture was centrifuged and the ethyl acetate layer was analyzed by GC.
Then, the recovered catalyst was reused directly for the next run. The reactor was sealed and purged with N 2 three times to remove the air at room temperature and subsequently charged with 0. When the reaction mixture was frozen, the gas was released immediately. After the reaction of lignin, the gas was released, passing through the ethyl acetate. Then, the reaction mixture in the reactor was transferred into a centrifuge tube. After that, the reactor was washed with the ethyl acetate used for the gas filtration, which was finally combined with the reaction mixture.
By centrifugation, the solid was separated from the reaction mixture, and the yield of the detectable products in the ethyl acetate layer was determined by GC. The separated solid was successively washed with acetone, and the used catalyst was recovered. Then, the collected liquid was subjected to rotavap to remove acetone solvent, and the lignin residue was obtained.
The mass of the recovered catalyst was nearly the same as that of the catalyst initially loaded. In the reaction, After the reaction, the autoclave was cooled to room temperature, and the gas was released. The liquid layers were transferred into a separatory funnel, and then the aqueous layer was removed. Desired benzene product was finally obtained.
Additional data available from authors upon request. Zhu, X. Xin X. Efficient petrochemical processes: technology, design and operation Wiley, Vaughan, B. A rhodium catalyst for single-step styrene production from benzene and ethylene. Science , — Davis, R. A non-porous supported-platinum catalyst for aromatization of n-hexane. Nature , — Squires, A.
Chemicals from coal. Mochida, I. Chemicals from direct coal liquefaction. Guo, X. Direct, nonoxidative conversion of methane to ethylene, aromatics, and hydrogen. Gao, J. Identification of molybdenum oxide nanostructures on zeolites for natural gas conversion. Morejudo, S. Direct conversion of methane to aromatics in a catalytic co-ionic membrane reactor.
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Long-term exposure means exposure of a year or more. Benzene causes harmful effects on the bone marrow and can cause a decrease in red blood cells, leading to anemia. It can also cause excessive bleeding and can affect the immune system, increasing the chance for infection. Some women who breathed high levels of benzene for many months had irregular menstrual periods and a decrease in the size of their ovaries.
It is not known whether benzene exposure affects the developing fetus in pregnant women or fertility in men. Animal studies have shown low birth weights, delayed bone formation, and bone marrow damage when pregnant animals breathed benzene. Long-term exposure to high levels of benzene in the air can cause leukemia, cancer of the blood-forming organs.
How you can protect yourself, and what to do if you are exposed to benzene First, if the benzene was released into the air, get fresh air by leaving the area where the benzene was released.
Moving to an area with fresh air is a good way to reduce the possibility of death from exposure to benzene in the air. If the benzene release was outside, move away from the area where the benzene was released.
If the benzene release was indoors, get out of the building. Removing your clothing Quickly take off clothing that may have benzene on it. Any clothing that has to be pulled over the head should be cut off the body instead of pulled over the head. If you are helping other people remove their clothing, try to avoid touching any contaminated areas, and remove the clothing as quickly as possible. Washing yourself As quickly as possible, wash any benzene from your skin with large amounts of soap and water.
Washing with soap and water will help protect people from any chemicals on their bodies. If your eyes are burning or your vision is blurred, rinse your eyes with plain water for 10 to 15 minutes. If you wear contacts, remove them after washing your hands and put them with the contaminated clothing.
Do not put the contacts back in your eyes even if they are not disposable contacts. If you wear eyeglasses, wash them with soap and water. You can put your eyeglasses back on after you wash them. Disposing of your clothes After you have washed yourself, place your clothing inside a plastic bag. Avoid touching contaminated areas of the clothing. Anything that touches the contaminated clothing should also be placed in the bag. Seal the bag, and then seal that bag inside another plastic bag. Disposing of your clothing in this way will help protect you and other people from any chemicals that might be on your clothes.
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