Dialkyl-, preparation

Triethyl phosphite is a colourless mobile liquid, insoluble in water. Trialkyl phosphites are valuable intermediates in the preparation of many organophosphorus compounds they readily form dialkyl esters of alkylphosphonic acids by the Arbusov reaction (p. 311). 

By the hydrolysis of dialkyl cyanamides with dilute sulphuric acid this method gives pure secondary amines. The appropriate dialkyl cyanamide is prepared by treating sodium cyanamide (itself obtained in solution from... 

The dialkyl disulphides may be prepared by the oxidation of an alkaline solution of a mercaptan with iodine, for example ... 

A convenient method for preparing pure AW-dialkyl anilines and substituted anilines directly from the corresponding amines consists in heating the latter with trialkyl orthophosphates ... 

The dibenzyl ketone has a very high b.p. (ca. 200°/21 mm.) and this remains in the flask when the unsymmetrical ketone has been removed by distillation. The dialkyl ketone has a comparatively low b.p. and is therefore easily removed by fractionation under normal pressure acetone is most simply separated by washing with water. In this way methyl benzyl ketone (R = CHj), ethyl benzyl ketone (R = CHgCH,) and n-propyl benzyl ketone (R = CHjCHjCH,) are prepared. By using hydrocinnamic acid in place of phenylacetic acid ... 

Organosilicon polymers. Silicon resembles carbon in certain respects and attempts have been made to prepare polymers combining carbon and silicon units in the molecule with the object of increasing the heat resistance of polymers. It has been found that the hydrolysis of a dialkyl-dichlorosilicane or an alkyltrichlorosilicane, or a mixture of the two, leads to polymers (Silicones), both solid and liquid, which possess great thermal stability. Thus dimethyldichlorosilicane (I) is rapidly converted by water into the silicol (II), which immediately loses water to give a silicone oil of the type (III) ... 

Dialkyl arylphosphonates and alkenylphosphonates are prepared by the coupling of halides or triflates with the dialkyl phosphonate 783[64l-643]. 

Dyatlova (193) reports the preparation of product 49, resulting from the dialkylation of 2-aminothiazole with a-chloroacetic acid under mild conditions (Scheme 36). 

N-(2-thiazolyl)dithiocarbamates are prepared by the action of carbon disulfide on 2-aminothiazoles (see Section III.3.C and Ref. 505). When refluxed with secondary amines these heterocyclic dithiocarbamates yield l,T-dialkyl-3-(2-thiazoIyI)thioureas (261) (491). 

Formation of esters of inorganic acids (Section 15 9) Alkyl nitrates dialkyl sulfates trialkyl phos phites and trialkyl phosphates are examples of alkyl esters of inor game acids In some cases these compounds are prepared by the direct reaction of an alcohol and the inorganic acid... 

Because they are widely used as solvents many simple dialkyl ethers are commercially available Diethyl ether and dibutyl ether for example are prepared by acid catalyzed condensation of the corresponding alcohols as described earlier m Section 15 7... 

The imide proton N-3—H is more acidic than N-1—H and hence this position is more reactive toward electrophiles in a basic medium. Thus hydantoins can be selectively monoalkylated at N-3 by treatment with alkyl haUdes in the presence of alkoxides (2,4). The mono-A/-substituted derivatives (5) can be alkylated at N-1 under harsher conditions, involving the use of sodium hydride in dimethylform amide (35) to yield derivatives (6). Preparation of N-1 monoalkylated derivatives requires previous protection of the imide nitrogen as an aminomethyl derivative (36). Hydantoins with an increased acidity at N-1—H, such as 5-arylmethylene derivatives, can be easily monoalkylated at N-3, but dialkylation is also possible under mild conditions. 

AIkyl-Ai,A/-diaLkyl-l-naphthalenecarboxamides are useful herbicides (86) and the 2,2-dimeth5lhydra2ide of 1-naphthalenecarboxyhc acid has been patented as a plant growth regulator (87). 2-Propynyl-2-naphthalenecarboxylate [53548-27-9] and similar esters are insecticides (88). 1-Naphthaleneacetic acid, the plant growth regulator, has been prepared from naphthalene, concentrated HCl, and paraformaldehyde without isolation of intermediate 1-chloromethylnaphthalene or l-naphthaleneacetonitnle (89). 

Dialkyl oxalates can be prepared by oxidative CO coupling in the presence of alcohols. The first reported example of the synthesis was in a PdCl2—CUCI2 redox system (30,31). 

UBE Industries, Ltd. has improved the basic method (32—48). In the UBE process, dialkyl oxalate is prepared by oxidative CO coupling in the presence of alkyl nitrite and a palladium catalyst. 

The dialkyl oxalate thus prepared is hydroly2ed to oxaUc acid and the corresponding alcohol. 

In the preparation of hydroperoxides from hydrogen peroxide, dialkyl peroxides usually form as by-products from the alkylation of the hydroperoxide in the reaction mixture. The reactivity of the substrate (olefin or RX) with hydrogen peroxide is the principal restriction in the process. If elevated temperatures or strongly acidic or strongly basic conditions are required, extensive decomposition of the hydrogen peroxide and the hydroperoxide can occur. 

Synthesis. Dialkyl peroxides are prepared by the reaction of various substrates with hydrogen peroxide, hydroperoxides, or oxygen (69). They also have been obtained from reactions with other organic peroxides. For example, dialkyl peroxides have been prepared by the reaction of hydrogen peroxide and alkyl hydroperoxides with alMating agents, eg, RX and olefins (33,66,97) (eqs. 24—27). 

Syimnetiical dialkyl peroxides have been prepared from alkyl hydroperoxides and lead tetraacetate. If tertiary dihydroperoxides are used, then cychc... 

DiaLkyl peroxides may be prepared by reaction of alcohols or alkyl trifluoromethanesulfonates with organomineral peroxides of siUcon, tin, and germanium (44,108), where Q = Sn and Ge ... 

Such copolymers of oxygen have been prepared from styrene, a-methylstyrene, indene, ketenes, butadiene, isoprene, l,l-diphen5iethylene, methyl methacrjiate, methyl acrylate, acrylonitrile, and vinyl chloride (44,66,109). 1,3-Dienes, such as butadiene, yield randomly distributed 1,2- and 1,4-copolymers. Oxygen pressure and olefin stmcture are important factors in these reactions for example, other products, eg, carbonyl compounds, epoxides, etc, can form at low oxygen pressures. Polymers possessing dialkyl peroxide moieties in the polymer backbone have also been prepared by base-catalyzed condensations of di(hydroxy-/ f2 -alkyl) peroxides with dibasic acid chlorides or bis(chloroformates) (110). 

Thermally unstable cycHc trioxides, 1,2,3-trioxolanes or primary o2onides are prepared by reaction of olefins with o2one (64) (see Ozone). Dialkyl trioxides, ROOOR, have been obtained by coupling of alkoxy radicals, RO , with alkylperoxy radicals, ROO , at low temperatures. DiaLkyl trioxides are unstable above —30° C (63). Dialkyl tetraoxides, ROOOOR, have been similarly produced by coupling of two alkylperoxy radicals, ROO , at low temperatures. Dialkyl tetraoxides are unstable above —80°C (63). 

Mono- and dialkyl derivatives can also be prepared using alkyl sulfates. Aryl chlorides are usually inert, unless activated by an electron-withdrawing group. Conversion to alkoxides allows formation of ethers. 

Another significant use for dialkyl dimethyl quaternary ammonium salts and alkylhenzyl dimethyl ammonium salts is in preparing organoclays for use as drilling muds, paint thickeners, and lubricants. 

A AlI lation. A number of methods are available for preparation of A/-alkyl and A[,A/-dialkyl derivatives of aromatic amines. Passing a mixture of aniline and methanol over a copper—zinc oxide catalyst at 250°C and 101 kPa (1 atm) reportedly gives /V-methylaniline [100-61-8] in 96% yield (1). Heating aniline with methanol under pressure or with excess methanol produces /V, /V-dimethylaniline [121 -69-7] (2,3). 

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