Esters free alcohol

Mixture of fatty esters, sterols/ triterpene alcohol esters, free alcohols, sterols and terpenes... 

C2H4N2O3, NH2CONHCOOH. Unknown in the free state as it breaks down immediately to urea and COi- The NH4, Ba, Ca, K and Na salts are known and are prepared by treating ethyl allophanate with the appropriate hydroxide. The esters with alcohols and phenols are crystalline solids, sparingly soluble in water and alcohol. They are formed by passing cyanic acid into alcohols or a solution of an alcohol or phenol in benzene. The amide of allophanic acid is biuret. Alcohols are sometimes isolated and identified by means of their allophanates. 

Hydroxy-2-methylpropanenitrile is then reacted with methanol (or other alcohol) to yield methacrylate ester. Free-radical polymerization is initiated by peroxide or azo catalysts and produce poly(methyl methacrylate) resins having the following formula ... 

A second mole of halogen adds with greater difficulty oxidative side reactions can be minimised by halogenating an ester instead of the free alcohol (26). 

The higher alcohols occur in minor quantities primarily as the wax ester (ester of a fatty alcohol and a fatty acid) in many oilseed and marine sources. Free alcohols octacosanol [557-61-9] C2gH gO, and triacontanol [28351-05-5] have been isolated in very small amounts from sugarcane and its... 

The irradiation of the provitamin has been achieved using the acetate and benzoate esters, although the free alcohol form of the provitamin is usually used (77). 

Jojoba. Jojoba oil [61789-91-1] is obtained from the seeds of the jojoba plant grown in semiarid regions of Costa Rica, Israel, Mexico, and the United States. The oil is made up of ca 80 wt % of esters of eicos-ll-enoic and docos-13-enoic acids, and eicos-ll- -l-ol, and docos-13- -l-ol, ca 17 wt % of other hquid esters, with the balance being free alcohols, free acids, and steroids. Jojoba oil is used primarily in the formulation of cosmetics. Hydrogenated jojoba oil is a wax used in candles and other low volume specialty apphcations. 

Solid esters are easily crystallisable materials. It is important to note that esters of alcohols must be recrystallised either from non-hydroxylic solvents (e.g. toluene) or from the alcohol from which the ester is derived. Thus methyl esters should be crystallised from methanol or methanol/toluene, but not from ethanol, n-butanol or other alcohols, in order to avoid alcohol exchange and contamination of the ester with a second ester. Useful solvents for crystallisation are the corresponding alcohols or aqueous alcohols, toluene, toluene/petroleum ether, and chloroform (ethanol-free)/toluene. Esters of carboxylic acid derived from phenols... 

This is followed by hydrolysi.s of the ester moieties with potassium carbonate and reesterification of the carboxy moiety with diazomethane to produce intermediate 65. The solitary free alcoholic hydroxyl at C-9 is oxidized with Collins reagent and the silyl ether groups are removed with acetic acid to give enprostil (63) [15]. 

The acid value of this on it alwavs below 1 and the ester value does not exceed 2 5.. A large amount of free alcohols, Uow.wcr, is present, the ester value after acetylation vaning from -16 m 129. 

This oil cqquIus only about 5 to b per cent, of esters and 8 per cent, of free alcohol. Tt is probable that the alrohol present is linalol and not geraniol. 

Thus as in the case of oil of bergamot, esterification is accompanied by a decrease in. the total proportion of linalol and in the proportion of free acid. These facts prove that, here also, the esters originate by the direct action of the acids on the alcohols. Under these conditions, as the plant develops, part of the linalol is esterified whilst another portion is dehydrated. So that not only does the proportion of free alcohol, but also that of the total alcohol decroase. But as the esterification process is completed, which happens when the flower commences to-fade, the total alcohols increase at a fairly rapid rate. 

It will be seen that (1) the acidity decreases during the maturing of the plant (2) as in all the cases previously considered, oil of geranium becomes ricber in esters during vegetation (3) tbe proportion of total alcohol increases slightly and the quantity of free alcohol decreases, but not to an extent corresponding with the increase of esters, so that in the course of esterification, which takes place in this case without dehydration, a small quantity of alcohol is produced. 

Linalyl Propionate.—This ester is also produced by condensing the free alcohol and the free acid by means of sulphuric acid. It has a somewhat fruity odour recalling that of bergamot, and is especially suitable for perfumes of the lily of the valley type. It is a colourless oil, boiling at 115° at 10 mm. pressure. 

Deduct the alcohols combined as esters from the total alcohols, which gives the amount of free alcohols. 

Cocking 1 has constructed a simple formula by which the amount of free alcohol may be accurately determined in the presence of any ester or mixture of esters, providing that these are unaffected by acetylation. 

Hydrolysis of the acetate ester with alkali, e.g., sodium methoxide in methanol, affords the free alcohol, 16/3-methyl-1,4,9( 11 )-pregnatriene-17o, 21-diol-3,20-dione. To a suspension of 3 grams of 16/3-methyl-1,4,9(11)-pregnatriene-17o,21-diol-3,20-dione-21-acetate in 40 ml of acetone is added at 0°C with stirring 2 grams of N-chlorosuccinimide and then 7 ml of a perchloric acid solution prepared by dissolving 0.548 ml of 70% perchloric acid in 33 ml of water. The resulting reaction mixture is stirred at 0°C for about 4 hours 45 minutes. 

The reaction product with monoethanolamine acts as a thickening agent [41,101] and with alcohols as an emollient [40]. Also reaction products with amino acids and oligo- or polypeptides for use in cosmetic formulations are known [43]. Sorbitan esters from ether carboxylates are described as emulsifiers or mild surfactants in cosmetic formulations [39] and alkyl ether carboxylic acid taurides as nonirritant anionic surfactants for cosmetic cleaners in particular [44]. Using unsaturated ether carboxylates it is possible to make viscous formulations based on combinations of unsaturated and saturated ether carboxylates [111]. Highly purified alkyl ether carboxylates based on alcohol ethoxylates with low free alcohol content have also been described [112]. 

Therefore, transesterification reactions frequently fail when R is tertiary, since this type of substrate most often reacts by alkyl-oxygen cleavage. In such cases, the reaction is of the Williamson type with OCOR as the leaving group (see 10-14). With enol esters, the free alcohol is the enol of a ketone, so such esters easily... 

Disconnection of the ester removes alcohol (18) and leaves (19). The amipo group will have to be put in by nitration and we already know (p 34) that we need the free acid (16) for this. The ether must therefore be disconnected first. 

Conversion of Free or Silylated Carboxylic Acids into Esters, Thioesters, Lactones, or Ketenes. Transesterification of Esters with Alcohols... 

In order to establish the correct absolute stereochemistry in cyclopentanoid 123 (Scheme 10.11), a chirality transfer strategy was employed with aldehyde 117, obtained from (S)-(-)-limonene (Scheme 10.11). A modified procedure for the conversion of (S)-(-)-limonene to cyclopentene 117 (58 % from limonene) was used [58], and aldehyde 117 was reduced with diisobutylaluminium hydride (DIBAL) (quant.) and alkylated to provide tributylstannane ether 118. This compound underwent a Still-Wittig rearrangement upon treatment with n-butyl lithium (n-BuLi) to yield 119 (75 %, two steps) [59]. The extent to which the chirality transfer was successful was deemed quantitative on the basis of conversion of alcohol 119 to its (+)-(9-methyI mande I ic acid ester and subsequent analysis of optical purity. The ozonolysis (70 %) of 119, protection of the free alcohol as the silyl ether (85 %), and reduction of the ketone with DIBAL (quant.) gave alcohol 120. Elimination of the alcohol in 120 with phosphorus oxychloride-pyridine... 

The qualitative average composition of beeswax is quite constant and is made up of hydrocarbons (14%), monoesters (35%), diesters (14%), triesters (3%), hydroxymonoesters (4%), hydroxypolyesters (8%), monoacid esters (1%), acid polyesters (2%), free acids (12%) and free alcohols (1%) [2,69 73]. 

Montan wax is obtained by solvent extraction of certain types of lignite or brown coal. It has a dark colour when not treated, but it is lighter when refined. Its chemical composition includes esters of C22 C32 acids (53%), free acids (17%), free alcohols (1 2%), ketones (3 6%) and terpenoids (20 23%) [85]. 

Another RP-HPLC procedure was applied for the study of the distribution and stability of steryl chlorin esters in copepod faecal pellets from diatom grazing. Pigments were sonicated for 15 min with acetone at 0°C and the procedure was repeated until the extract became colourless. The organic phase was evaporated and the fraction containing the free alcohols was separated by TLC (silica stationary and dichloromethane mobile phases) and analysed by gas chromatography. RP-HPLC measurements were performed in an ODS... 

Similarly, Yamashita has utilised free alcohols to trap the vinylketene intermediates formed in the reactions of aryl and heteroaromatic carbenes, resulting in >8, y-unsaturated esters.26,45 If a secondary amine is used in the... 

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