Mono hydroxy benzenes

MONO-PHENOLS, MONO-HYDROXY BENZENES Phenol, CeHft—OH, Hydroxy Benzene, Carbolic Acid... 

Mono-chlor-benzene Di-brom-benzene Hydroxy benzene Amino benzene Methyl benzene... 

Mono-hydroxy toluene, being a di-substitution product of benzene, i.e.j methyl hydroxy benzene exists in isomeric forms as ortho, meta and... 

Only two of the higher homologous mono-hydroxy phenols will be mentioned. These are the two isomeric mono-hydroxy cymenes, cymene being i-methyl 4-iso-propyl benzene. They are as follows ... 

The proofs for the above constitutions are as follows (i) Thymol yields cymene, i-methyl 4-iso-propyl benzene, by loss of the hydroxyl oxygen by means of phosphorus penta-sulphide. (2) Carvacrol may be synthesized from potassium cymene sulphonate by fusion with potassium hydroxide. Therefore both must be mono-hydroxy cymenes. (3) Thymol by means of phosphorus pentoxide splits off the iso-propyl radical yielding meta-cresol and propylene. (4) Carvacrol by the same reaction yields ortho-cresol. Therefore in thymol the hydroxy group is meta to the methyl group while in carvacrol it is ortho. The following relationships are thus established. 

The poly-phenols or poly-hydroxy benzenes are obtained from the dry distillation products of wood. The methods of synthesis are in general those for the mono-phenols though the diazo reaction does not usually work well with amino phenols. Also some of the methods of preparation used for poly-phenols do not apply to the mono-phenols. In general properties they resemble the mono-compounds, but they are usually more easily soluble in water, react more readily and are characterized by their strong reducing properties. 

I ogaUol.—Pyrogallol, the vicinal or 1-2-3-tri-hydroxy benzene, is also called pyro-gallic acid as it is obtained by heating gallic acid which is a mono-carboxy tri-hydroxy benzene. 

Guaiacol.—A phenol ether which needs more detailed mention is the mono-methyl ether of pyrocatechinol which is known as guaiacol. We have stated that with water in the presence of aluminium chloride guaiacol yields pyrocatechinol or 1-2-di-hydroxy benzene,... 

We have previously stated (p. 612) that mono-phenols have the hydroxyl group replaced by the amino group when they are treated with ammonia zinc chloride. Similarly, with greater ease, the diphenols may have one hydroxyl group replaced by an amino group when heated with ammonia, thus yielding amino phenols. This method is used in preparing meta amino phenol from resorcinol, meta-di-hydroxy benzene. 

Problem 1.—Interpret the data in Table III in accordance with predictions based upon Rule I. Why would the solubility of naphthalene in mono-hydroxy alcohols up to Co be predicted to lie below 14 g. per 100 g. solvent Given the solubility in acetic acid, do the solubilities in propionic, butyric and valeric acids agree with predictions Why would one expect naphthalene to be less soluble in toluene than in benzene Predict qualitatively the solubility of naphthalene in the solvents formic acid, heptanoic acid, ethyl benzene, etc. Compare the solubilities in hydrocarbons of the two series CflH2B+2 and CnH2tt , where n=6. Do the facts agree with predictions Predict qualitatively the solubility of naphthalene in ethyl acetate. 

A mixture of 0.1 mol of N-mono-1-p-chlorobenzohydrylpiperazine and 0.1 mol of 1-chloro-2-(2-hydroxy-ethoxy)-ethane is heated for 3 hours to 150°C. The mass is then taken up in 100 ml of benzene and 100 ml of a 10% aqueous solution of NaOH decanting takes place, and the benzene solution is washed with water and the solvent is evaporated. Vacuum distilling of the residue yields 1-p-chlorobenzohydryl-4-[2-(2-hydroxy-ethoxy)-ethyl]-piperazine, BP 220 C/0.5 mm Hg. 

Resorcinol and its mono- and diacetates can be separated from one another and from hexachlorophene by TLC after extraction from dermatological preparations silica gel layers were used, prepared with 0.01 M aqueous sodium tungstate as complexing agent, benzene-dioxan-acetic acid (90 +10 + 2) as solvent and ferricyanide-ferric chloride (Rgt. No. Ill) for detection [64]. Hexyhesorcinol and hexachlorophene can be separated on silica gel G layers, using methyl isobutyl ketone [64]. A separation of dichlorophene and hexachlorophene has been possible with n-heptane,saturated with acetic acid,and layers of a hand prepared mixture of silica gel and starch binder [26]. Some of the components of tar oils and their TLC are also of pharmaceutical interest [130]. TLC-data for dithranol have also been described [15]. lodo-chlorhydroxyquin(5-chloro-8-hydroxy-7-iodoquinoline) has been separated from possible contaminants originating from its synthesis, by TLC in methanol on polyamide-calcium sulphate layers (5g polyamide + 3.5 g calcium srdphate + 10 ml water) [90]. 

An alternative mechanism for the formation of mono- and di-hydroxy-terephthalate groups is by the formation of benzene ring hydroperoxides [2176] ... 

Preparation by treatment of methyl 2-hydroxy-6-methoxy-4-methylbenzoate (methyl mono-O-methyl-p-orsellinale) (m.p. 94-96°) with sodium methylsulfinyl-methide (SM) formed in situ. SM was obtained by action of sodium hydride (3 equiv) with DMSO (7 equiv) in benzene at 50° for 1 h. (78%) [5592]. 

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