Camphors

Synonyms 1,7,7-trimethyl bicyclo[2,2,l]-2-heptanone 2-bomanone 2- oxobomane  

White crystalline solid with an aromatic odor mp 178.8°C (353.84°F) sublimes at 204 C (399.2 F) density 0.992 at 25°C (77°F) soluble in alcohol, ether, acetone, and benzene, insoluble in water. 

Flammable solid flash point (closed cup) 65.6°C (150°F) vapor pressure 0.18 torr at 20°C (68°F) vapor density 5.2 autoignition temperature 466°C (871°F) fire-extinguishing agent none reported water or foam may cause frothing water spray may be applied carefully on the surface to blanket and extinguish a fire. i//-Camphor forms explosive mixtures with air the LEL and UEL values are 0.6 and 3.5% by volume of air, respectively. It may react violently with chromium trioxide and other strong oxidizers. 

GC-EID, HPLC, and GC/MS air samples using the NIOSH Method 1301 (see Section 29.15). 

Vapors of camphor can irritate the eyes, nose, and throat. In humans, such irritation may 

Methyl chlorosulfonate 74 may be prepared by reaction of chlorosulfonic acid with either methyl sulfate or methyl chloroformate (Equations 28 and 29).  

Camphor-3-sulfonic acid may also be obtained (73% yield) by treatment of camphor with sulfur trioxide-dioxan at —35 °C, followed by standing the reaction mixture at room temperature (4 hours) and neutralization with sodium hydroxide. This reaction and that with methyl chlorosulfonate probably proceed via the enolic form of the ketone. The formation of 8- and 10-camphorsulfonic acids is considered to involve Wagner and Nemetkin rearrangements of the carbocations formed in the acidic media.  

As mentioned in Chapter 4, p 83, 3-benzylidenecamphor reacts with excess chlorosulfonic acid (six equivalents) to give a good yield of the /7-sulfonyl chloride surprisingly there was no attack on the camphor ring. Other arylidene-camphor derivatives reacted similarly with chlorosulfonic acid, giving exclusive sulfonation of the aryl ring (see Chapter 4, p 83). 

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Borneol and isoboineol are respectively the endo and exo forms of the alcohol. Borneol can be prepared by reduction of camphor inactive borneol is also obtained by the acid hydration of pinene or camphene. Borneol has a smell like camphor. The m.p. of the optically active forms is 208-5 C but the racemic form has m.p. 210-5 C. Oxidized to camphor, dehydrated to camphene. 

Present in citronella and valerian oils, tur penline, ginger, rosemary and spike oils. It is produced artificially by the elimination of hydrogen chloride from bornyl chloride (artifi cial camphor) or from isobornyl chloride, by the dehydrogenation of borneol and isobor-neol and by the action of elhanoic anhydride on bornylamine. Chiral. 

Ordinary commercial camphor is (-i-)-cam phor, from the wood of the camphor tree. Cinnamonum camphora. Camphor is of great technical importance, being used in the manufacture of celluloid and explosives, and for medical purposes, /t is manufactured from pinene through bornyl chloride to camphene, which is either directly oxidized to camphor or is hydrated to isoborneol, which is then oxidized to camphor. A large number of camphor derivatives have been prepared, including halogen, nitro and hydroxy derivatives and sulphonic acids. 

Used medicinally as a carminative and stimulant. It is injected in olive oil solution in cases of circulatory collapse. It is a popular remedy for colds and is a constituent of many lina-ments. Camphorated oil is 20% solution in olive oil. 

Epicamphor is prepared from methyl-( + )-bornylene-3-carboxylate, and does not occur naturally. The smell of epicamphor differs slightly from that of camphor. 

Light oil of camphor is an almost colourless fraction containing a small amount of camphor, about 30% of cineole and the remainder terpenes. 

Dark oil of camphor consists very largely of safrole. 

Me2C = CHCOCH= CMca- Yellow liquid having a camphor-like odour m.p. 28 C, b.p. 198-5°C. It is formed when propanone is saturated with HCl and allowed to stand. Resembles camphor in many of its properties and is a solvent for cellulose nitrate. Used to prepare diisobutyl ketone (reduction). 

By oxidation with permanganate it forms pinonic acid, C,oH,<503, a monobasic acid derived from cyclobutane. With strong sulphuric acid it forms a mixture of limonene, dipentene, terpinolene, terpinene, camphene and p-cymene. Hydrogen chloride reacts with turpentine oil to give CioHijCl, bomyl chloride, artificial camphor . 

Interesting pattern formations also occur in surfactants spreading on water due to a hydrodynamic instability [52]. The spreading velocity from a crystal may vary with direction, depending on the contour and crystal facet. There may be sufficient imbalance to cause the solid particle to move around rapidly, as does camphor when placed on a clean water surface. The many such effects have been reviewed by Stemling and Scriven [53]. 

Sulphur dioxide is oxidised by chlorine in the presence of charcoal or camphor to give sulphur dichloride dioxide sulphuryl chloride), SOjCl ... 

The 20th century brought important advances in the field of organic chemistry. In the first decades of the century, the syntheses of inaeasingly complex molecules were accomplished. Some notable compounds synthesized during that time were a-terpinol (WH. Perkin, 1904), camphor (G. Komppa, 1903), and tropinone (R. Robinson, 1917 Figure 10.3-28). 

The following oxidation of camphor to camphor-quinone illustrates the oxidising action of selenium dioxide, and readily gives a crystalline product. 

When camphor (I) is heated with selenium dioxide in acetic acid, the methylene group next to the carbonyl group is oxidised also to a carbonyl group, to form camphorquinone (II). Note that the compound (II) is not a true quinone but a 1,2-diketone ... 

In this preparation, the ( + ) or dextro-rotatory (natural) camphor or the ( ) or racemic (synthetic) camphor can be used. Perform the oxidation in a fume-cupboard. 

Place a mixture of 5 g. of camphor, 6 g. of powdered selenium dioxide and 5 ml. of acetic anhydride in flask fitted with a reflux water-condenser. Heat the flask in an oil-bath for 3 hours at 140-150 so that gentle boiling occurs shake the mixture from time to time. 

The m.p. of the quinone obtained from the optically inactive camphor is almost identical with the above values, obtained from dextro-camphor. 

III. Depression of the Freezing-point of Camphor (Rast s Method). 

On the other hand, molten camphor can exist as either the keto or the enol... 

Moreover, it is important that a determination of the Molecular Depression Constant of the camphor should... 

DETERMINATION OF MOLECULAR DEPRESSION CONSTANT OF CAMPHOR, using Solute of Known Molecular Weight (Naphthalene, Ck,Hj). 

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