Methyl vinyl ketone, atmosphere

Biesenthal, T. A., and P. B. Shepson, Observations of Anthropogenic Inputs of the Isoprene Oxidation Products Methyl Vinyl Ketone and Methacrolein to the Atmosphere, Geophys. Res. Lett., 24, 1375-1378 (1997). 

A mixture of 63.1 g. (0.5 mole) of 2-methyl-l,3-cydohexane-dione (Note 1), 52.6 g. (0.75 mole) of methyl vinyl ketone (Note 2), about 0.25 g. (3 pellets) of potassium hydroxide, and 250 ml. of absolute methanol is placed in a 500-ml. round-bottomed flask fitted with a reflux condenser and a drying tube (Note 3). The mixture is heated under reflux for 3 hours, and the dione gradually goes into solution. At the end of this period, methanol and the excess methyl vinyl ketone are removed by distillation under reduced pressure (Notes 4 and 5). The residual liquid is dissolved in 250 ml. of benzene, a Dean-Stark phase-separating head is attached, and 20 ml. of solvent is removed by distillation at atmospheric pressure to remove traces of water and methanol. The solution is cooled well below the boiling point, 3 ml. of... 

A. 2-Trimethylsilyloxy-l,3-butadiene (1). An oven-dried 500-ml., three-necked, round-bottomed flask is fitted with two oven-dried addition funnels, a glass stopper, and magnetic stirrer, and placed in a 80-90° oil bath. Under an inert atmosphere, methyl vinyl ketone (25.0 g., 0.357 mole) in 25 ml. of dimethylformamide and chlorotrimethylsilane (43.4 g., 0.400 mole) in 25 ml. of dimethylformamide are added over 30 minutes to a magnetically stirred solution of triethylamine (40.5 g., 0.400 mole) in 200 ml. of dimethylformamide (Note 1). The reaction gradually darkens from colorless to yellow or dark brown, and supports a white precipitate of triethylamine hydrochloride. The reaction is set up to run overnight, or ca. 14 hours. 

Nitropropane (17.8g 0.2mol) and diisopropylamine (10ml) in 200ml of chloroform are stirred at 60 °C under a nitrogen atmosphere. Methyl vinyl ketone (CAUTION) (7 g, 0.1 mol) is added dropwise to this solution. After 3 hours another portion of methyl vinyl ketone (7 g, 0.1 mol) is added and the solution stirred for 24 hours. The solution is washed sequentially with water, 10 per cent aqueous hydrochloric acid, 5 per cent sodium hydrogen carbon-... 

Methyl vinyl ketone (entry 3) and the tert-butyl cation (entry 4) are also reactive toward complex 3. The naphthalenium complexes resulting from the addition of these electrophiles will add the conjugate base of dimethyl malonate (generated in situ from a combination of dimethyl malonate (DMM) and diisopropylethylamine (DIEA)) to complete the tandem additions. Oxidation of the resulting complexes yields cis-l,4-dihydronaphthalenes. The entire sequence of complexation, tandem addition, and demetalation employed for all entries in Table 4 can be performed using bench-top conditions (i.e., a non-inert atmosphere). 

Four milliliters of 1 AT aqueous sodium hydroxide solution is added to a mixture of 300 g. (5.2 moles) of acetone and 100 g. (0.86 mole) of aqueous 35% formaldehyde solution. The mixture is held at room temperature for 3-4 hours and then neutralized with 4 ml. oi 1 N hydrochloric acid. The excess acetone is distilled off on a water bath heated to 80-85°, and 2-4 g. of anhydrous zinc chloride is added to the residue. The mixture is distilled on an oil bath, and the distillate is collected as long as it comes over colorless. The distillate is treated with potassium carbonate, and the organic material is separated and dried over sodium sulfate. Distillation at 130 mm. pressure gives a 25-35% yield of methyl vinyl ketone boiling at 33-34°. Some decomposition occurs if the distillation is carried out at atmospheric pressure, where the product boils at 80°. 

The use of copper chromite at 40°C and atmospheric pressure was not very effective for selective carbonyl group hydrogenation. Unsaturated alcohols were produced from unsaturated aldehydes in low yields at low conversions and not at all from methyl vinyl ketone. 28 With unconjugated, unsaturated aldehydes, copper chromite is effective as a selective hydrogenation catalyst. Hydrogenation of 46 at 140°-160°C and 200 atmospheres gave better than 70% of the diene diol, 47. Increasing the temperature to 240°C resulted in the complete saturation of 46 (Eqn. 18.28). 29... 

The reaction did not require dry solvents or inert atmosphere and afforded the desired adducts in 42-98% yield. As expected, the more reactive acrolein and methyl vinyl ketone gave very good results with both acyclic and cyclic p-ketoesters and p-diketones and, surprisingly, acrylonitrile and methyl acrylate, reported to be totally inactive under Lewis acid catalysis, " afforded the corresponding adducts with a-acetylbutyrolactone in high yield (77 and 98% respectively). In the reaction with crotonaldehyde, a 1 1 mixture of... 

B. (Ft)-(+)-2-Methyl-2-(3-oxobutyl)cydohexanone (2). The solution of imines 1 is cooled in an ice bath and 72.5 mL (61.0 g, 0.870 mol, ca. 1.05 equiv) of freshly distilled methyl vinyl ketone (Note 3) is added with a syringe, with magnetic stirring, under a nitrogen atmosphere. The flask is then heated at ca. 40°C for 24 hr. 

Methyl vinyl ketone, purchased from Aldrich Chemical Company, Inc., is dried over anhydrous potassium carbonate for 0.5 hr. The now slightly-colored oil is filtered and distilled under a nitrogen atmosphere at reduced pressure, bp 55°C (260 mm). The coiorless center of the distiilate is coliected over a few miiiigrams (ca. 

In the present work a large set of actinic spectra recorded in the EUPHORE chamber under various atmospheric conditions has been obtained and used for the calculation of photolysis frequencies of 17 organic carbonyl compounds. From a statistical analysis of the photolysis frequencies calculated for the compounds an analytical form for Jfd) has been derived. For unsaturated compounds (methyl vinyl ketone, methacrolein, acrolein and crotonaldehyde) < ) g is negligible, although those cxompounds possess absorption spectra reaching the near visible. 

Pedersen and Sehested (2002) showed that the aqueous-phase reaction of isoprene with ozone was insignificant for the processing of isoprene in the atmosphere. They estimated the overall and individual lifetimes of isoprene due to reactions with ozone and the hydroxyl radical, at 25 "C and typical in-cloud conditions. The results (Table 3) indicate that clouds generally should not contribute much to the processing of isoprene in the atmosphere. Only in the aqueous phase, were the lifetimes of isoprene due to reactions with ozone and with OH radicals comparable. Similar conclusions were drawn for methyl vinyl ketone, while for methacrolein the clouds could reduce the overall atmospheric lifetime by 50 %. 

These compounds, exemplified by acrolein, crotonaldehyde, and methyl vinyl ketone, are known to react with ozone and with OH radicals. Photolysis and N03 radical reaction are of minor importance. Under atmospheric conditions the 03 reactions are also of minor significance (Atkinson and Carter, 1984), leaving the OH radical reaction as the major loss process. For the aldehydes, OH radical reaction can proceed via two reaction pathways OH radical addition to the double bond and H-atom abstraction from the -CHO group (Atkinson, 1989). For crotonaldehyde, for example, the OH reaction mechanism is given in Fig. 3. As can be noted from Fig. 3, these a,/3-unsaturated aldehydes are expected to ultimately give rise to a-dicarbonyls such as glyoxal and methylglyoxal. For the a,/3-unsaturated ketones such as methyl vinyl ketone, the major... 

The oxidation of isoprene, CH2=CHC(CH3)=CH2, in the atmosphere has not yet been fully delineated and thus remains speculative. Hanst et al. (1980) have discussed some of several possibilities. The successive addition of OH and 02 to either of the two double bonds of isoprene may be modeled in analogy of that to propene and is expected to give formaldehyde and methacroleine or formaldehyde and methyl vinyl ketone as the products. The reaction of isoprene with ozone is expected to produce dioxirane and... 

Montzka, S. A., Trainer, M., Goldan, P. D., Kuster, W. C., and Fehsenfeld, F. C. (1993) Isoprene and its oxidation products, methyl vinyl ketone and methacrolein, in the rural atmosphere, J. Geophvs. 

The coupling reaction of phenyl vinyl ketone (1.5 eq.) and p-nitrobenz-aldehyde was carried out at 25 °C wiA [Rh(COD)2]OTf (5mol%), PPhs (12 mol%), KOAc (50 mol%) under H2 (1 atm) atmosphere to give the aldol product 54 in 92% yield (Scheme 18) [31]. Omission of KOAc decreased the yield to 79%. The aromatic aldehydes gave the corresponding aldol products in good to excellent yields, whereas ahphatic aldehydes resulted in diminished yields. Methyl vinyl ketone as an enolate source can be tolerated, giving a 70% yield of the aldol product 58. 

Warneke, C, Holzinger, R., Hansel, A., Jordan, A., Lindinger, W., Poschl, LF., Williams, J., Hoor, P, Fischer, H., Crutzen, P.J., Scheeren, H.A., Lelieveld, J. (2001) Isoprene and its oxidation products methyl vinyl ketone, methacrolein, and isoprene related peroxides measured online over the tropical rain forest of Surinam in March 1998. Journal of Atmospheric Chemistry, 38,167-185. 

Photooxidation of isoprene in the atmosphere was thought to yield only lighter and more volatile products such as formaldehyde, methacrolein, and methyl vinyl ketone. Evidence that the formation of hygroscopic polar products such as 115 can give rise to aerosols by gas-to-particle formation processes has opened a new panorama for the role of isoprene in the atmosphere. Under simulated atmospheric conditions, photooxidation of isoprene by ozone was shown to be relatively slow and to occur mainly by reaction with OH radicals [65]. Furthermore, when the OH -initiated... 

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