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Introduction to Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
Aldehydes are organic compounds containing an alkyl group, aryl group, or a hydrogen attached to a carbonyl group, =CO, with an adjacent hydrogen, −CHO; for example, methanal (formaldehyde), HCHO; ethanal (acetaldehyde), CH3CHO.
Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Aldehydes are polar compounds with a carbonyl structure. Alcohols and aldehydes are both polar so they mix well together. There is a rule in chemistry that like materials mix with like materials. Other aldehyde compounds include acetaldehyde, crotonaldehyde and acrylaldehyde. Aldehydes are used as solvents, disinfectants, preservatives and pesticides and in the manufacture of plastics. Formaldehyde is designated as a carcinogen. Polarity is also important when selecting the right type of firefighting foam. Polar compounds require polar solvent foam, also known as alcohol-type foam.
Aldehydes and Ketones. Acyl Addition Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
The carbonyl group, C=O, is the main structural and reactive feature of aldehydes and ketones. A ketone has two carbon groups on either side of the carbonyl [R(C=O)R] whereas an aldehyde has at least one hydrogen attached to the carbonyl [R(C=O)H]. How can a carbon–carbon double bond be contrasted and compared with a carbon–oxygen double bond?
Control of pollutants in supercharged partially adiabatic diesel engine with carburetted methanol and crude karanja oil blended with DEE
Published in International Journal of Ambient Energy, 2021
Ravi Kumar Kotturi, M. V. S. Murali Krishna, B. Sudheer Prem Kumar, M. Ravi Chandra
The major pollutant exhausted from the diesel engine is aldehydes with carburetted alcohol and vegetable oil. Aldehydes are carcinogenic in nature, which cause health hazards to human beings. The aldehydes measurement is not sufficiently reviewed in the literature with ceramic-coated partial adiabatic diesel engine. DNPH method was incorporated to determine the aldehydes in the exhaust of the engine (Kuta, Kiyohiko, and Shiaki 1980; Sasi Kumar et al. 2011). The exhaust of engine was filtered and predetermined quantity (2 l/m) was fed to the engine by means of rotometer. The exhaust of the engine was heated up to 140°C with heater, which was incorporated in the exhaust–circuit. There was an arrangement to bubble the exhaust gas through dinitrophenyl hydrazine (2,4 DNPH) solution. The hydrazones, which were formed, extracted into chloroform and were determined by employing HPLC to find out the percentage concentration of individual aldehydes like formaldehyde and acetaldehyde in the exhaust of the engine. The advantage of this method was to determine individual concentration of formaldehyde and acetaldehyde simultaneously in the engine exhaust.
Effects of potassium carbonate on acetaldehyde gasification in supercritical water
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Liang Zhao, Hongfang Zhou, Yanshan Yin, Qian Lu, Jun Zhang
Figure 2(f) further reports that K2CO3 is conducive to increasing the gasification efficiency, especially at the high temperature of 550 ~ 600 °C. In our previous study (Zhao et al. 2014), the potassium salts have the negative effects on gasification efficiency of formaldehyde gasification in supercritical water. Formaldehyde and acetaldehyde are both aldehydes. Tschannen, Gonzales, and Lee (2013) found that the decomposition mechanisms of formaldehyde and acetaldehyde were different. On the one hand, the decomposition pathways of acetaldehyde gasification are more complex than that of formaldehyde gasification. On the other hand, the gasification efficiency of formaldehyde gasification (Zhao et al. 2014) is lower than the values in Figure 2(f). Therefore, for aldehydes, the intermediates of degradation are the key to further understand the gasification mechanisms in supercritical water.
β-mCoPc/Cu-BDC composites for oxidation of benzyl alcohol to benzaldehyde
Published in Journal of Coordination Chemistry, 2020
Yanbing Yin, Hang Yang, Zhaosong Xin, Chengli Zhang, Guopeng Xu, Yumeng Wang, Guohua Dong, Xun Zhang
Aldehyde and ketone compounds, a large category of important organic intermediates and raw materials, are commonly formed by oxidation of alcohols and widely used in paints, pharmaceuticals, perfumes, fine chemicals and other industries [1, 2]. Specifically, benzaldehyde has an important value in the production of drugs, fine chemicals and spices. More importantly, with the economic development and progress, the demand of benzaldehyde is increasing at a rate of 7% per year [3]. The oxidation of benzyl alcohol into benzaldehyde has therefore become important in organic synthesis [4, 5]. However, suitable catalyst is important for obtaining high yield of benzaldehyde in this process [6–8]. Generally, noble metal or transition metal oxides were catalyst. For good catalytic activity in oxidation of benzyl alcohol, Liu et al. loaded Pd nanoparticles with a diameter 3.5 nm onto the surface of nanosheet F-MOF by impregnation. This composite catalyst showed good stability and catalytic activity for oxidation of benzyl alcohol [9]. Zhang et al. synthesized supported bi-functional catalyst of Pd@MIL-101 by supporting Pd nano-particles onto MIL-101 carrier by chemical encapsulation method. This catalyst has high catalytic activity in alcohol oxidation in toluene. Synergistic cooperation of MIL-101 and Pd can be the primary reason for enhanced catalytic performance [10]. However, these catalytic reactions not only produce a large amount of toxic and environmentally harmful heavy metal salt contaminants, but also led to some undesirable benzoic acid. Therefore, it is especially important to explore some high-efficiency and environmentally friendly catalysts in the catalytic oxidation of benzyl alcohol [11, 12].