Dichloromethane alternatives

Neutral alumina (35 g) is added to a solution of lc (0.760 g, 2 mmol) dissolved in a minimum amount of dichloromethane (5 mL) at room temperature and the reaction mixture is thoroughly mixed using a vortex mixer. The adsorbed material is dried in air (beaker) and placed in an alumina bath inside the microwave oven. Upon completion of the reaction as followed by TLC examination (10 min), the product is extracted into dichloromethane (4x15 mL). Removal of the solvent, under reduced pressure yielded the product which is purified by crystallization from methanol-dichloromethane. Alternatively, the adsorbed material is charged directly on a silica gel column to afford the pure product, 3-(4-hydroxy-phenyl)-l-propanol 2c in 78% yield, mp 53-55 °C, in ethyl acetate-methanol (4 1, v/v) as an eluent. 

In a small mortar grind 2 g of green or brightly colored fall leaves (don t use ivy or waxy leaves) with 10 mL of ethanol, pour off the ethanol, which serves to break up and dehydrate the plant cells, and grind the leaves successively with three 1-mL portions of dichloromethane that are decanted or withdrawn with a Pasteur pipette and placed in a test tube. The pigments of interest cU e extracted by the dichloromethane. Alternatively, place 0.5 g of carrot paste (baby food) or tomato paste in a test tube, stir and shake the paste with 3 mL of ethanol until the paste has a somewhat dry or fluffy appecu-ance, remove the ethanol, and extract the dehydrated paste with three 1-mL portions of dichloromethane. Stir and shake the plant material with the solvent in order to extract as much of the pigments as possible. 

An alternative way to produce methyl chloride (monochloromethane) is the reaction of methanol with HCl (see later in this chapter, Chemicals from Methanol ). Methyl chloride could he further chlorinated to give a mixture of chloromethanes (dichloromethane, chloroform, and carhon tetrachloride). 

Alternatively, to an ice-cold solution of the alcohol (0.325 mmol) in dichloromethane (10ml) was added boron trifluoride etherate (4mmol), and the mixture was stirred at 0°C for lh. Work-up as above gave the alkenes as a 6 94 mixture of (E) (Z) isomers, in 99% yield (g.l.c.). 

Hexen-l-ol and triethylamine were purchased from Acros Organics and used without further purification. Alternatively, 5-hexen-l-ol may be prepared from 2-(chloromethyl)tetrahydropyran according to the literature procedure for the preparation of 4-penten-l-ol (Brooks, L. A. Snyder, H. R. Org. Synth. Coll. Vol. Ill 1955, 698). Dichloromethane (certified ACS) was purchased from Fisher Scientific and was used as received. 

The phosphorus-boron bond of BisP -BH3 81 is cleaved by treatment with tri-fluoromethanesulfonic acid in toluene followed by treatment with aqueous KOH or, alternatively, with tetrafluoroboronic acid in dichloromethane and subsequent... 

The main drawback to this reaction is the toxicity of diazomethane and some of its precursors. Diazomethane is also potentially explosive. Trimethylsilyldia-zomethane is an alternative reagent,42 which is safer and frequently used in preparation of methyl esters from carboxylic acids.43 Trimethylsilyldiazomethane also O-methylates alcohols.44 The latter reactions occur in the presence of fluoroboric acid in dichloromethane. 

Costley et al. [113] have evaluated the use of a range of organic solvents (dichloromethane, water, acetone, hexane, xylene) in the microwave extraction of oligomers from PET and have compared MAE to alternative extraction approaches (Soxhlet, Pan-bomb). 

This state emphasises its capacity to dissolve chemicals and natural substances of similar way as do different organic solvents such as hexane, acetone or dichloromethane. Therefore, the first applications focused on the extraction of natural substances as an alternative to using organic solvents. Thus, removal of caffeine (coffee or tea) with supercritical C02 is the most mature application at industrial level and is also used in the extraction of hops or cocoa fat. 

An alternative procedure described by the checkers comprises reduction of the amount of dichloromethane to 30 ml. and... 

A ground mixture of iron(III) nitrate and HZSM-5 zeolite, termed zeofen , has also been used both, in dichloromethane solution and in solid state under MW irradiation conditions [101]. It has been suggested that the zeolite aids the reproducibility of the reaction but any other aluminosilicate support would probably be equally effective. Recent studies point out attractive alternatives that do not employ any of the solid supports in such oxidations with nitrate salts [102]. 

The conversion of alcohols directly into the structurally related hydrocarbons by ionic hydrogenation can provide a means of synthesis for compounds that would be extremely difficult or impossible to obtain by other methods. A good example is the synthesis of 2-terr-butyladamantane (12, R = Me). This interesting, highly strained compound may be synthesized in moderate overall yield by a conventional multiple-step route.149 Alternatively, it is obtained in 90% isolated yield upon treatment of a dichloromethane solution of the readily available 2-/c/7-bulyI -2-adamantanoI (11, R = Me)150 and one equivalent of either tri-n-hexylsilane151152 or triethylsilane153 with trifluoroacetic acid at room temperature (Eq. 16). 

Alternatively, lipospheres might be prepared by a solvent technique. In this case, the active agent, the solid carrier, and the phospholipid are dissolved in an organic solvent such as acetone, ethyl acetate, ethanol, or dichloromethane. The solvent is then evaporated and the resulting solid mixed with warm buffer solution, and mixing is continued until a homogeneous dispersion of lipospheres is obtained. 

The intramolecular insertion reactions of nitrenoids into G-H bonds as described above provide an attractive alternative to conventional methods of amine formation. Both carbamate and sulfamate C-H insertions have been applied successfully to the total syntheses of natural products. - The first application of carbamate G-H insertion was reported by Trost in the total synthesis of methyl-L-callipeltose 118 (Equation (92)).230 Intermolecular G-H insertion of carbamate 117 using 10mol% Rh2(OAc)4, PhI(OAc)4, and DTBMP (2,6-di-/ / -butyl-4-methylpyridine) in dichloromethane (40 °C) furnished methyl-L-callipeltose 118 in 63% yield. In an another independent total synthesis of 118, Panek performed this step in refluxing benzene and improved the yield to 93%.231... 

A Ogawa, DP Curran. Benzotrifluoride a useful alternative solvent for organic reactions currently conducted in dichloromethane. J Org Chem 62, 450, 1997. 

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