15356-70-4 Usage
Chemical Properties
Different sources of media describe the Chemical Properties of 15356-70-4 differently. You can refer to the following data:
1. Free-flowing or agglomerated, crystalline powder or prismatic or acicular, colourless, shiny crystals
2. Menthol has three asymmetric carbon atoms in its cyclohexane ring
and, therefore, occurs as four pairs of optical isomers.The configurations of four
of these isomers are given; the other four are their mirror images.(1R,3R,4S)-(?)-Menthol,,; (1R,3S,4S)-(+)-neomenthol,; (1R,3S,4R)-(+)-
isomenthol,; (1R,3R,4R)-(+)-neoisomenthol,.
(?)-Menthol is the isomer that occurs most widely in nature. It is the main component
of peppermint and cornmint oils obtained from the Mentha piperita and
Mentha arvensis species. Esterified menthol also occurs in these oils (e.g., as the
acetate and isovalerate).Other menthol stereoisomers may be present in these oils
as well.
Physical properties
Physical Properties. The eight optically active menthols differ in their sensory
properties. (?)-Menthol has a characteristic peppermint odor and also
exerts a cooling effect. The other isomers do not possess this cooling effect and
are, therefore, not considered to be “refreshing.” Racemic menthol occupies an
intermediate position; the cooling effect of the (?)-menthol present is distinctly
perceptible.
The enantiomeric menthols have identical physical properties (apart from their
specific rotations), but the racemates differ from the optically active forms in, for
example, theirmelting points.Although the differences between the boiling points
are small, the (racemic) stereoisomers can be separated by fractional distillation.
Boiling points (in °C at 101.3 kPa) are as follows:
rac-neomenthol, 211.7
rac-neoisomenthol 214.6
rac-menthol, 216.5
rac-isomenthol, 218.6
Other physical constants of commercially available levorotatory and racemic
menthols are as follows: (?)-menthol, mp 43 °C, [α]20
D ?50° (ethanol, 10%);
racemic menthol, mp 38 °C.
Chemical Properties. Hydrogenation of menthols yields p-menthane; oxidation
with chromic acid or catalytic dehydrogenation yields menthones. Dehydration
under mild conditions yields 3-p-menthene as the main product. Reaction with
carboxylic acids or their derivatives yields menthyl esters, which are used mainly
as aroma substances and in pharmaceutical preparations and formulations. The
esterification of menthols with benzoic acid is used on an industrial scale in the
resolution of racemic menthol.
Occurrence
Has apparently not been reported to occur in nature
Preparation
By hydrogenation of thymol followed by separation from its other isomers.
Indications
Menthol, a cyclic alcohol (derived from peppermint, other mint oils, or prepared
synthetically), relieves itching by generating a cool sensation. It is usually used in
0.25% to 2% concentrations but is present in concentrations as high as 16% in
some OTC products.
Toxicity evaluation
The acute oral LD50 in rats has been reported as 3180 mg/kg by Jenner, Hagan, Taylor, Cook & Fitzhugh (1964) and as 2900 mg/kg by Herken (1961). The acute oral LD50 in cats was reported to be 1500-1600 mg/kg (Flury & Seel, 1926). The sc LD50 in the mouse was reported as 1400-1600 mg/kg (Flury & Seel, 1926) and the ip LD50 as 750 mg/kg in the rat (Herken, 1961) and 1500-1600 mg/kg in the cat (Flury & Seel, 1926). In rabbits, the ip LD50 was reported to be approximately 2000 mg/kg (Herken, 1961), while the acute dermal LD50 exceeded 5000 mg/kg (Levenstein, 1973).
Safety Profile
Moderately toxic by
ingestion, intraperitoneal, and subcutaneous
routes. An eye and skin irritant. K%en
heated to decomposition it emits acrid
smoke and irritating fumes. See also
MENTHOL and 1-MENTHOL.
Metabolism
Rabbits are said to eliminate 59% of dl-menthol as glucuronide (Williams, 1938).
Check Digit Verification of cas no
The CAS Registry Mumber 15356-70-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,5,3,5 and 6 respectively; the second part has 2 digits, 7 and 0 respectively.
Calculate Digit Verification of CAS Registry Number 15356-70:
(7*1)+(6*5)+(5*3)+(4*5)+(3*6)+(2*7)+(1*0)=104
104 % 10 = 4
So 15356-70-4 is a valid CAS Registry Number.
InChI:InChI=1/2C10H20O/c2*1-7(2)9-5-4-8(3)6-10(9)11/h2*7-11H,4-6H2,1-3H3
15356-70-4Relevant articles and documents
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Brode,Van Dolah
, p. 1157,1158 (1947)
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Highly selective synthesis of menthols from citral in a one-step process
Trasarti,Marchi,Apesteguia
, p. 484 - 488 (2004)
We report for the first time the selective synthesis of menthols from citral in a one-step process. Bifunctional metal/acid catalysts active and selective for menthol synthesis were developed by studying the individual steps involved in the reaction pathway leading to menthols from citral. The metallic component was selected by testing silica-supported metals for citral hydrogenation to citronellal. Acid site requirements to efficiently isomerize citronellal to isopulegols were investigated on different solid acids. Potential bifunctional metal/acid catalysts were then prepared and tested for citral conversion to menthols. The best catalyst was Ni/Al-MCM-41, which yielded about 90% menthols and gave 70-75% of racemic (±)-menthol in the menthol mixture.
Continuous synthesis of menthol from citronellal and citral over Ni-beta-zeolite-sepiolite composite catalyst
Er?nen, Kari,M?ki-Arvela, P?ivi,Martinez-Klimov, Mark,Muller, Joseph,Murzin, Dmitry Yu.,Peurla, Markus,Simakova, Irina,Vajglova, Zuzana
, (2022/04/03)
One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60–70 °C under 10–29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71–76% and 72–74% were obtained from citronellal and citral respectively at the contact time 4.2 min, 70 °C and 20 bar. Citral conversion noticeably decreased with time-on-stream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amount of defuctionalization products observed during citral conversion, especially at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepared by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N2 physisorption and FTIR techniques to perceive the interrelation between the physico-chemical and catalytic properties.
Continuous flow synthesis of menthol: Via tandem cyclisation-hydrogenation of citronellal catalysed by scrap catalytic converters
Zuliani, Alessio,Cova, Camilla Maria,Manno, Roberta,Sebastian, Victor,Romero, Antonio A.,Luque, Rafael
, p. 379 - 387 (2020/02/13)
A continuous flow synthesis of menthol starting from citronellal catalysed by scrap catalytic converters is reported. The reaction was conducted in a tandem system connecting in series two catalytic systems, with the first having Lewis acid properties (favouring the cyclisation of citronellal to isopulegols) and the second having hydrogenation catalytic activity (catalysing the hydrogenation of isopulegols to menthols). A Lewis acid catalyst was prepared by supporting iron oxide nanoparticles over a waste material, i.e. the ceramic core of scrap catalytic converters (SCATs) via a microwave assisted method. Most importantly, SCATs, containing a low residual noble metal content, could be directly employed in the second step as hydrogenation catalysts. The reaction was performed studying the influence on the yield and selectivity to (-)-menthol of various reaction parameters (T, p and flow rate). Under the best reaction conditions (at a flow rate of 0.1 mL min-1 and at 373 K and 413 K for cyclisation and hydrogenation steps respectively) a conversion of >99% of (+)-citronellal to (-)-menthol with 77% final yield was achieved.
