Rogers

, p. 106,107 (1972)

Cardew,Burwell

, p. 6289 (1960)

One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: Insights into the major reaction pathways

Xing, Shiyou,Lv, Pengmei,Wang, Jiayan,Fu, Junying,Fan, Pei,Yang, Lingmei,Yang, Gaixiu,Yuan, Zhenhong,Chen, Yong

, p. 2961 - 2973 (2017/02/05)

For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6-C8 olefins over the catalysts' Br?nsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6-C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Br?nsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.

Kinetics of -CH2CH2- Hydrogen Release from a BN-cyclohexene Derivative

Giustra, Zachary X.,Chou, Lien-Yang,Tsung, Chia-Kuang,Liu, Shih-Yuan

supporting information, p. 2425 - 2428 (2016/08/16)

Complete -CH2CH2- dehydrogenation of 1,2-dimethyl-1,2-BN-cyclohexene (1) was achieved using a Pd/C catalyst in a gas-phase microreactor. Arrhenius analysis yielded an activation energy (Ea) of 10.3 ± 0.3 kcal mol-1 and a pre-exponential factor (A) of 2.2 ± 0.2 (log A), respectively. These terms reflect a lesser kinetic favorability in comparison to those determined for all-carbon dimethylcyclohexene (Ea = 8.6 ± 0.3 kcal mol-1, log A = 3.6 ± 0.1). Despite being isostructural and isoelectronic with a C=C bond, the B-N bond of 1 thus appears to confer a different measure of activity with respect to Pd-catalyzed -CH2CH2- dehydrogenation.

Unsaturated aldehydes as alkene equivalents in the Diels-Alder reaction

Taarning, Esben,Madsen, Robert

supporting information; experimental part, p. 5638 - 5644 (2009/05/30)

A one-pot procedure is described for using α,β-unsaturated aldehydes as olefin equivalents in the Diels-Alder reaction. The method combines the normal electron demand cycloaddition with aldehyde dienophiles and the rhodium-catalyzed decarbonylation of aldehydes to afford cyclohexenes with no electron-with-drawing substituents. In this way, the aldehyde group serves as a traceless control element to direct the cycloaddition reaction. The Diels-Alder reactions are performed in a diglyme solution in the presence of a catalytic amount of boron trifluoride etherate. Subsequent quenching of the Lewis acid, addition of 0.3% of [Rh(dppp)2Cl] and heating to reflux achieves the ensuing decarbonylation to afford the product cyclohexenes. Under these conditions, acrolein, crotonaldehyde and cinnamaldehyde have been reacted with a variety of 1,3-dienes to afford cyclohexenes in overall yields between 53 and 88%. In these transformations, the three aldehydes serve as equivalents of ethylene, propylene and styrene, respectively.