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English to Chinese: CDOM release by DF in the central Bohai Sea General field: Science Detailed field: Chemistry; Chem Sci/Eng
Source text - English Phytoplankton blooms can be an important source of autochthonous chromophoric dissolved organic matter (CDOM) in surface oceans. Here we report the first detection and optical characterization of CDOM produced during a Dictyocha fibula bloom occurring in the western central Bohai Sea in mid-summer 2019. The mean CDOM absorption coefficient at 330 nm (aCDOM(330)) in the surface water of the bloom area (3.16 ± 0.48 m-1) was 2.5 times higher than that of the adjacent bloom-absent area (1.26 ± 0.34 m-1). The aCDOM(330) increased exponentially to a maximum with increasing chlorophyll a and cell abundance of D. fibula, indicating a steady state was reached between production and consumption of CDOM. The biological index (BIX) of the fluorescent DOM (FDOM) showed little variation between bloom and background areas. The combination of these observations points to an extensive production of autochthonous CDOM by D. fibula in the bloom area. Mass budgeting indicates that the CDOM source from D. fibula (aCDOM(330): 1.98 ± 0.48 m-1) accounted for 63% of the CDOM stock in the bloom area. The spectral slope coefficients over 275–295 nm (S275–295) in the bloom area (range: 0.0228–0.0241 nm-1; mean: 0.0235 nm-1) were substantially lower than those in the bloom-absent area (range: 0.0240–0.0311 nm-1; mean: 0.0271 nm-1), suggesting a high-molecular-weight nature of the D. fibula-derived CDOM. The freshly produced CDOM contained two humic-like FDOM components and one protein-like FDOM component, and the three FDOM components were depleted in fresh CDOM relative to their counterparts in CDOM within the background area. Owing to the episodic nature of algal bloom-driven CDOM production, future attention should be paid to accelerated biogeochemical cycles (e.g., spiked oceanic trace gas emission) associated with CDOM photochemistry during algal blooms which can be easily missed for pre-scheduled field surveys.
English to Chinese: A snythesis method for a compound in 3 steps General field: Law/Patents Detailed field: Chemistry; Chem Sci/Eng
Source text - English The present invention is an improved method for the preparation of 4-fluoro-3-piperidin-4-yl-benzyl)-carbamic acid tert-butyl ester, compound of formula I. The invention is directed to a method of synthesis for the compound of formula I in three steps, comprising formation of 5-((tert-butoxycarbonyl)aminomethyl)-2-fluorobenzeneboronic acid (compound 11), reaction of compound 11 under Suzuki coupling conditions to yield (4-fluoro-2-pyridin-4-yl-benzyl)-carbamic acid tert-butyl ester and selective hydrogenation of the aforementioned product under hydrogenation conditions yields compound I. The invention is also directed to the intermediates 5-((tert-Butoxycarbonyl)amino-methyl)-2-fluorobenzeneboronic acid (compound 11), and (4-fluoro-2-pyridin-4-yl-benzyl)-carbamic acid tert-butyl ester (compound 13).
1. A method for preparing 5-((tert-butoxycarbonyl)aminomethyl)-2-fluorobenzene-boronic acid, comprising boronation of 4-(tert-butoxycarbonyl)aminomethyl)-fluorobenzene with a boronic acid forming agent under boronation conditions, and then quenching the resultant mixture with an aqueous acid to yield 5-((tert-butoxycarbonyl)aminomethyl)-2-fluoro-benzeneboronic acid.
2. The method of claim 1 wherein the boronation conditions uses a superbase.
3. The method of claim 2 wherein the superbase is a combination of an organolithium reagent of formula RLi where R is an alkyl or aryl group having 1-12 carbons and a bulky potassium alkoxide such as potassium tert-butoxide or potassium tert-pentoxide and the like.
4. The method of claim 3 wherein the superbase is a combination of n-butyllithium and potassium tert-butoxide.
5. The method of claim 1 wherein the boronation conditions uses a boronic acid forming agent which is a trialkyl boronate.
6. The method of claim 5 wherein the trialkyl boronate is selected from trimethyl borate, triethyl borate, tripropyl borate, triisopropyl borate, tributylborate and the like.
7. The method of claim 6 wherein the trialkyl boronate is triisopropyl borate.
8. The method of claim 1 wherein the boronation conditions uses a boronation solvent which is an ether solvent selected from diethyl ether, THF, 2-methyltetrahydrofuran, MTBE, dimethoxyethane and the like.
9. The method of claim 8 wherein the ether solvent is THF.
10. The method of claim 1 wherein the boronation conditions uses a boronation reaction temperature from about -100 oC. to about -30 oC.
11. The method of claim 10 wherein the boronation reaction temperature is from about -70 to about -45 oC.
12. The method of claim 1 wherein the aqueous acid is HCl or H3PO4.
Member since Sep '22
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