Acetone, addition

After standing for several hours a small amount of precipitate (about 2 to 3 mg) was formed and was then separated from the solution. This solution was diluted with an additional 2 ml of acetone and again allowed to stand for several hours. During this time about 4 to 5 mg of noncrystalline precipitate formed. This solid was separated from the solution and an additional 2 ml of acetone was added to the solution. On standing, vitamin began to crystallize in the form of red needles. After standing for 24 hours, the crystalline material was separated, yield 12 mg. By further dilution of the mother liquor with acetone additional crystalline precipitate formed (from U.S. Patent 2,738,302). 

Minor product formed. b Five other products formed. c Acetone addition-product formed. 

A suspension of a cell line (usually T lymphocyte lines such as HG, HUT-78, or CEM) infected with HIV is spotted on microscope slides, air dried, and fixed in acetone. Addition of uninfected cells to the suspension provides a means for detecting nonspecific reactions in the same smear. Typical localized fluorescence of infected cells is seen after reaction with positive sera. Little or no fluorescence is seen with negative sera. 

Acetone also reduces the solubility of lactose, upon which a procedure to recover lactose from whey is based (Kerkkonen et al. 1963). Acetone is added to concentrated whey (18 to 20% lactose) in amounts sufficient to precipitate some of the impurities. After these are filtered out, the gradual addition of acetone to over 65% allows recovery of 85% of the lactose during a 3.5 hr period. The yield of lactose and rapidity of crystallization are influenced by the rate of acetone addition. 

The majority of fluorescent probes are water-insoluble and must be dissolved in an organic solvent prior to addition to an aqueous reaction medium containing the DNA to be labeled. Suitable solvents are identified for each fluorophore, but mainly DMF or DMSO are used to prepare a stock solution. Some protocols utilize acetone when labeling DNA. However, avoid the use of DMSO for sulfonyl chloride compounds, as this group reacts with the solvent. For oligonucleotide labeling, the amount of solvent added to the reaction mixture should not exceed more than 20% (although at least one protocol calls for a 50% acetone addition—Nicolas etal., 1992). 

Industrial processes were developed for the selective partial hydrogenation of 4-vinylcyclohexene with Ni catalysts exhibiting minimized isomerization activity in the presence of additives298,299. For example, supported nickel arsenides prepared by reducing nickel arsenate with NaBFLt display high selectivity in the formation of 4-ethylcyclohexene (96% selectivity at 96% conversion on Ni-As-Al2C>3, 398 K, 25 atm H2, acetone additive). 

Fig. 6. Effect of aeration (0.030 vvm) through Teflon-made diffusers (system 1) and acetone addition (50 mM) (system 2) on cofermentation of synthetic solutions of glucose and xylose in STR containing marbles. In both cases, the beads were prepared with an internal ratio of P. stipitis/S. cerevisiae of 4 g/g, and the gel fraction was almost 0.1 g/g. The initial cell concentration in system 1 was 8.6 x 1011 cells/L while that in system 2 was 8.42 x 10u cells/L.

Substituted-l-benzotelluropyrylium salts react with dry acetone at room temperature to afford the corresponding acetone addition products 35 and 36 (Equation 9) <1999J(P1)1665>. The exocyclic unsaturated adduct 36 appears to form from acid-promoted dehydrogenation of the initially formed acetone adduct. 

The RC-1 work was extended to a study of the exotherm resulting from the acetone addition step (to consume the excess sodium borohydride). The data obtained from RC-1 work was invaluable in calculating the cooling requirements needed for larger-scale work and for further optimization of the process. 

The kinetics of acetone addition have also been studied for several aryldisilane-derived (l-sila)hexatrienes, including 21a-c47,51, 4651 and 62 (from photolysis of 61 equation 47), where the reaction follows a different course than that of simpler silenes such as 1952. In these cases, the reaction proceeds via two competing pathways, formal [2 2]-cycloaddition and ene-addition. Unlike the case with the simpler silenes, however, the ketone rather than the silene acts as the enophile in the reaction, presumably because this alternative has the formation of an aromatic ring as an added driving force. 

Fresh urine was collected from Asian elephant females that were at the height of estrus.150 Urine was extracted with an immiscible organic solvent and concentrated. Bioassay involved reconstitution of the extract concentrate in acetone, addition of the acetone solution to (in active) urine samples from females that were not in estrus, and application to concrete slabs or logs. Observers, who were unaware of the sites where samples had been placed, recorded the flehmening responses of test bull elephants. These studies convincingly demonstrated that in Asian elephants the estrous state, and probably the receptivity of the female, is revealed by a substance or substances that can be extracted from the urine 150 of females in estrus. 

In addition, if nucleation from an aqueous solution occurs in the crystallizer—either by excess time before addition of acetone or by subcooling below 15 C in the crystallizer—the resulting crystals will have different crystal morphology. The crystals from an aqueous solution grow rapidly, once nucleated, and produce crystals that dissolve slowly and thereby fail to meet the dissolution time and PSD specifications. An example of the crystals that can nucleate and grow in aqueous solution—before acetone addition—is shown in Fig. 11-3a, where the very large cubic crystals have grown in an aqueous solution, whereas the smaller ones were formed after acetone addition. 

The distillate will be produced at a rate of 60 kmol/h with a purity of 94% mole acetone. Additionally, a small stream S of 20 kmol/h with 74% mole acetone, required for further downstream processing, will be produced as a liquid side draw from the column. The column will be operated at a reflux ratio of 2.0. 

C. Then 160 ml of room temperature acetone was added over 30 min while maintaining 50-55 °C. The suspension was cooled to 5 °C after acetone addition and maintained at 5 °C for 1 h. The resulting crystallized product was collected by filtration and washed with 30 ml of acetone. The product was dried at 50 °C in a vacuum oven (-80 kpa) for 24 h to give the corresponding benzamidine in yields of 80-85% with a purity of >99% by HPLC. 

This method of preparation is preferable to that using acetone,7 since excess [(C2 H 5)4 N]Br can be precipitated by acetone addition and acetone degradation can introduce colored impurities. 

Acylsilanes. 2-Silyl-l,3-dithianes undergo oxidative hydrolysis on exposure to NBS in aqueous acetone. Addition of a base (triethylamine or barium hydroxide) prevents further conversion of the products to carboxylic acids. 

Fluorophenylacetic acid was transformed into the unsaturated acid 48 by reaction with 2 mol equiv. of i-PrMgCl, followed by acetone addition, dehydration, and crystallization. The tetra-substituted double bond was then hydrogenated under high pressure in an ad hoc designed continuous-stirred tank reactor system and in the presence of the Ru complex 49 (substrate/catalyst ratio =1000) to afford (.5)-acid 50 in 93.5% e.e. Crystallization of its sodium salt upgraded the e.e. to 98%. 

Acetone addition and condensation have been extensively studied [175, 188. 253-255] Figure 7). Acetone can undergo addition to form diacetone alcohol which can be dehydrated to produce mesityl oxyde. used in the synthesis of methyl isobuihyl ketone (MIBK). Moreover, as already described in section 3. the puKluci distribution for acetone condensation is a useful way to reveal information about the surface chemistry of the catalyst [45. 235]. 

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