نتایج جستجو برای: esters
تعداد نتایج: 28401 فیلتر نتایج به سال:
Phthalates are esters of phthalic acid, mainly used as plasticizer in polymeric packaging materials. The main objective of this research was to determine the exact roots of the phthalate esters in the Iranian flexible/laminated packaging films commercially used for food products such as ketchup, spaghetti, mayonnaise, black tea and snack foods. This investigation was carried out by analyzing th...
3-monochoropropane-1, 2-diol (3-MCPD) and 2-monochloropropane-1,3-diol (2-MCPD) and glycidol esters (GE) have been known as food contaminants. These compounds are formed during high-temperature process of different food products such as coffee, edible oils, infant formula, potato based products, bakery products, malt, cooked meats, soy sauces and pickles. In vegetable oils, these compounds are ...
BACKGROUND Biodiesel is a mixture of fatty acid short-chain alkyl esters of different fatty acid carbon chain lengths. However, while fatty acid methyl or ethyl esters are useful biodiesel produced commercially, fatty acid esters with branched-chain alcohol moieties have superior fuel properties. Crucially, this includes improved cold flow characteristics, as one of the major problems associate...
Enantioselective reduction of the carbonyl group of three phenylglyoxylic acid esters (methyl, ethyl, and n-propyl esters, 2-4) was conducted using blended plant materials (roots of carrot, beetroot, celeriac and parsley; apple). All used biocatalysts transformed these esters to the corresponding mandelic acid esters with high yield, preferably into the respective R-enantiomer. Butanedione addi...
There are several lines of evidence which suggest that the liver is a major source of plasma cholesterol esters. First, eviscerated rats cannot maintain a normal concentration of cholesterol esters in the plasma (1); second, when isotopically labeled mevalonic acid is administered to rats, the specific radioactivity of the hepatic cholesterol esters initially exceeds that of the plasma choleste...
A. Introduction B. Acid-Catalysed Esterification and Transesterification 1. General mechanism 2. Methanolic hydrogen chloride 3. Methanolic sulfuric acid 4. Boron trifluoride-methanol 5. Other acidic catalysts C. Base-Catalysed Transesterification 1. General mechanism 2. Sodium and potassium methoxide catalysts 3. Organic base catalysis D. Diazomethane and Related Reagents 1. Diazomethane and m...
Twenty-two new esters of natural (-)-cephalotaxine with synthetic acids possessing widely divergent structural features have been synthesized. Murinichloroethyl carbonate (27) esters of cephalotaxine are the most active of this group; this activity is less than that of harringtonine and other naturally occurring cephalotaxine esters. Other synthetic esters exhibiting activity are methyl cephalo...
The abuse of esters of natural androgenic steroids in cattle fattening and sports is hard to control via routine urine testing. The esters are rapidly hydrolysed in vivo into substances which are also endogenously present in urine. In veterinary control strange findings of 17beta-testosterone and 17alpha-testosterone in urine are often ignored because of the lack of statistically sound referenc...
Temperature-dependent techniques (differential scanning calorimetry, polarizing microscopy, and x-ray scattering and diffraction techniques) were used to compare the properties of human plasma low density lipoproteins (LDL) with its extracted lipid classes. Three types of thermal transitions were characterized: (a) a reversible transition in intact LDL near body temperature associated with a li...
Part A I. General methods S1-S2 II. Synthesis of boronate esters (Table 1) S3-S6 III. Competition studies (Table 1) S7 IV. Synthesis of haloboronate esters (Scheme 1) S8-S13 V. Selective Suzuki-Miyaura coupling with haloboronate esters (Table 2) S14-S18 VI. Deprotection of boronate esters (Table 2) S19-S22 VII. Total synthesis of ratanhine (Scheme 3) S23-S39 Part B VIII. NMR spectra Part C IX. ...
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