Ester number

J. Yield Icompari d ailh drv mati-rialj O O per coot., r/j-j 08741 an + 0 38 acid iiuiuhec l.j O ester number 2I5 4 ester nombcr after acetylation 28fj. 3 soluble in 0 8 and more volume 80 per cent, alcohol t.ot euUrely soluble in 70 per cent, alcohol. 

The number of milligrammes of KOH used to saponify 1 gram of the oil (minus that required for the free acids) is termed the ester number. From this figure, which is now known, the percentage of esters present in a given oil may be rapidly calculated from the formula—... 

Ester Number. Per Cent. Acetate. Per Cent. Alcohol. Per Cent. Alcohol in the Original Oil. Per Cent. Acetate. Per Cent. AIcohoL Per Cent. Alcc ol in the Ori nal Oil. Ester Number. 

Ester-lack, m. ester varnish, -saure, /. ester acid, -verseifung, /, ester saponification, -lahl,/, ester number. 

Acid number 20-35 ester number 165-200 carbonyl number 20-75 [638]. 

Acid number 175-235, corresponding to an acid content of 71-95% (calculated as myristic acid) ester number 4-35 ketone content (calculated as irone) 9-20% soluble with ethanol in all proportions at 50 °C [674]. 

The number of milligrams of KOH necessary to saponify 1 gram of the oil represents the saponification number or, more accurately, the ester number of the oil. 

From the ester number the content in esters or in alcohol corresponding with the esters is calculated by the following formulae, it being assumed that the esters are acetates, as is commonly the case ... 

The ester number for any essential oil may vary within more or less wide limits (see Table XXXIV), but its determination is of importance in the identification of an oil, the detection of adulteration, and for judging of the quality of the oil. With some oils, the esters represent the odoriferous principle, e.g., linalyl acetate in bergamot, lavender and petit-grain oils, bomyl acetate in pine-needle oil and menthyl acetate in mint oil, the value of these Oils being deduced from the ester content. 

The ester number also serves for the detection of fatty oils, which have very high saponification numbers. 

Alcohols with Esters.—When an essential oil contains free alcohol and also esterified alcohol, to ascertain the amount of the free alcohol it is necessary to determine the ester number (as in paragraph 8, above) on the oil as it stands and the acetyl saponification number, the jree alcohol being then calculated by means of the above formula. The esterified alcohol (acetate) is calculated from the ester number by means of formula (2) on page 279 total alcohol = free alcohol + esterified alcohol. 

Acid and Ester Numbers.—These are determined as indicated on p. 279, the acidity being expressed also as per cent, of acetic add (acid number x 0-1071 --= % of C2H402). From the acid number the percentage... 

Of this residue, dissolved in a little neutral alcohol, the acid and ester numbers are determined, these being due to resinous, fatty and waxy substances naturally present in the bergamot oil. The ester number is converted into the corresponding percentage (n) of linalyl acetate (see paragraph 2) and the quantity of this ester contained in the percentage ( -) of residue left by the oil then calculated from the formula, (n x r)/ioo. This amount of linalyl acetate is subtracted from that found in the oil, as in paragraph . 

The residue on evaporation Of the genuine oil is 5-6% and its ester number 138-180, corresponding with 47-6-63% of linalyl acetate the 5-6 grams of residue are thus equivalent to about 2VJ-3-8 grams of linalyl acetate. Oil of lemon, terpenes, rectified bergamot oil or mineral oils diminish the residue... 

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