DAVIS : ETHERIFICATION OF DERIVATIVES OF ,B-NAPHTHQL. 33 IV.-Etherification of Derivatives of ,&Naphthol. By WILLIAM A. DAVIS. IN the following pages, an account is given of the etherification of derivatives of P-naphthol by heating the naphthol with a mixture of alcohol and sulphuric acid (Henriques, compare Gattermann, Annalen, 1887,244, 72). It is shown that, whereas @naphthol yields an almost theoretical amount of ether, most of its derivatives can only be very partially etherified. As no action occurs at the ordinary temperature, in the first series of experiments a mixture of 2 grams of purified naphthol with 2 grams of the alcohol and 0.8 gram of sulphuric monohydrate was gently boiled during 6& hours on the sand-bath in a test-tube attached to a condenser. VOL.LXXVII. D34 DAVIS : ETHERIFCCdTLON OF DERIVATIVES OF B-NAPHTHOL. To free the ether from unchanged naphthol, an excess of dilute caustic soda was then added, and the mixture gently warmed, a preliminary experiment having shown that this could be done without hydrolysis or dissolution of the ether taking place. The ether was collected on a tared filter-paper, which had previously been exposed in a weighing bottle in a vacuum until its weight was constant, and after being thoroughly washed, was dried in a vacuum desiccator and weighed. The results obtained are given in Table I. Owing t o a considerable proportion of the alcohol being converted into ethyl ether by the action of the sulphuric acid at the temperature at which the mixture boiled, it was generally observed that the latter separated, after about 3 hours, into two layers, of which the upper contained the alcohol and sulphuric acid, whilst the lower consisted of the naphthyl ether and unchanged.naphthol. Owing to this separation, little etherification occurred after the third hour. It was found, how- ever, that at loo", whilst the formation of ethyl ether was largely pre- vented, that of the naphthyl ether was not interfered with ; in addition, the disturbing influence which is undoubtedly exercised on the etheri- fication by varying the rate of ebullition was entirely excluded. Table I1 gives the results obtained at 100'. In these experiments, the mixture was heated during a much longer period than in the experi- ments recorded in Table I, and a definite limit of etherification was attained ; it is doubtful whether this limit had been reached in the first series of experiments, as will appear on comparing the two sets of results.The method of heating a t first adopted was to surround the tube containing the etherification mixture with boiling water, but the results obtained were, in some cases, vitiated by moisture permeating the cork; subsequently the lower portion only of the tube was heated by passing it through a cork fitted into the neck of a steam-bath con- structed from a sheet-iron can by soldering six short tubes 1 inch in diameter round the central neck. A condenser, fitted to the central neck, served to keep the volume of water in the can practically constant. Table I11 gives the results of experiments carried out a t looo, using methyl instead of ethyl alcohol; these values are probably not quite so trustworthy as those of Table 11, for two reasons.First, the mix- ture used boiled below loo", and a considerable decrease in its amount occurred owing to the formation of methyl ether; secondly, a small proportion of the naphthyl ether sublimed, and thus a change in the condition of equilibrium was introduced. The latter circumstance probably accounts for the fact that the amounts of ether obtained with methyl are higher than those obtained with ethyl alcohol ; in experi- ment 2, especially, much sublimation occurred. The results obtained with 3-bromo-%naphthol are possibly slightly higher than the trueDAVIS : ETHERIFICATION OF DERlVATIVES OF @-NAPHTHOL.35 B-Naphthol....... ................. , , . . . . . . . . . . . , . . . . . . . . , . . . . 3'-Bromo-2-naphthol . . . . . . . . . . . . l-Bromo-2-naphthol . . , . . . . . . . . . 9 9 ,) ..... * ...... values, owing to the fact that 3'-bromo-2-methoxynaphthalene does not melt below 100' when warmed with dilute caustic soda, so that small quantities of unchanged naphthol probably remained occluded ; more- over, much of the product sublimed. The alcohol used boiled at 66*0-66*5O under 759 mm. pressure. Similar experiments were made with propyl alcohol (b. p. 96-25-97' under 74'7.5 mm. pressure) ; the results are given in Table IV. I n the case of 1 : 3'-dibromo-2-naphthol, resinous substances insoluble in caustic soda were formed owing to the occurrence of secondary change.6 64 6* 64 62 TABLE I.-EthwiJication at the boiling point. No. ?f experi- ment. 1 2 3 4k 5 6 7 8 9 10" 11 12 13" 1 4 15 16 17 18 19 20 21t 2 2 t 23 24 25 26" 27 28" 29 30 Naphthol. Time in hours. 9 , 7 , Y9 Y , >> 7 ) a . . . . . . . . . . . ) ) ... ... ..... , , ,, ...... . ..... ,) ...... * ..... . . . . . . . . . . . . 1 - Chloro-2-naphthol . . . . , . . . . . . . l-Iodo-2-naphthol . . , . . . . . . . . . . . . 1 : 3'-Dibrorno-2-naphthol. .. , . . 9 , 7 , ............ 9 , Y ) ,? $ 9 9 , ,, , l 9 ) 7 ) .... ... ..... , , ,) ...... I ..... ,) ............ ,, .... * ....... ,, ....... ..... ,) ............ 7 7 ... ......... . . . . . . . . . . . . 1 -ChIoro-3'-bromo-2-naphthol. Y 9 9 7 # ) * 7 ) 9 , ), * 62 1 : 3~Dichloro%-naphthl .... ..:I 64 9 3 .. . . . . . 9 , Tribromo-2-naphthol (m. p. 155") .. .... .. . ... .. . . . . ..:. .. ... 1 -Ni tro12-naphthol. . , . . . . . . , , . . . . I 61 Percentagl yield of ether. 83 .O 84.1 68-0 69.7 9 -7 20'2 23 -1 2'1 4 '1 5.0 8 *1 10.0 9'4 7'6 9.7 1'4 1 -25 0 *7 3 '4 0'0 0.0 3 -9 2.3 0.9 1 '5 0'0 0.0 0.0 0 '87 1' Map. of product weighed. 36" 37 77-78 76-77 54-56 55-58 64-65 62-64 6 4-6 5 55-56 55-56 in form 74-76 79-80 79 89 89-90 88 65-70 54-58 - - 65-67 75 74 74 - - - 96-98 M.p. of pure ether. 37.50 37-5 80 80 66 66 66 66 66 66 58 58 94 94 94 94 94 94 94 77 77 77 77 d. - - - - - 104 In all experiments except those marked * and t, the proportions in grams mere-naphthol : ethyl alcohol : sulphuric acid = 2 : 2 : 0-8 ; in those marked with an asterisk, the moZeculas* proportions mere the same as in the etherification of /3-naphthol, namely, 1 mol.naphthol : 3-12 mols. alcohol: 0.59 mol. acid. I n two experiments, Nos. 21 and 23, 0 236 DAVlS : ETHEHIFIC'ATLON OF DEHLVATIVES OF @-NAPHTHOL. the proportion of sulphuric acid was the same as in the experiments with /3-naphthol, but 2 grams of alcohol were used. Unsatisfactory results were obtained in experiments 5,6,7, 14,15,and 16 with l-bromo- and 1 : 3'-dibromo-%-naphthol, owing to the fact that the mixture was boiled too rapidly, this giving rise to compounds insoluble in dilute caustic soda, which seriously interfered with the purity of the ether. Moreover, on filtering the dilute, alkaline solution of the unchanged naphthol, oxidation apparently occurred, and the solution became purple in colour, depositing a finely-divided purple or brownish powder in the pores of the filter paper, thus preventing further filtration.I n the later experiments (Nos. 8, 9, 10, 17, 18, 19), the ebullition was careful regulated and the filtration hastened by using a filter-pump ; under these conditions, the ether weighed was nearly pure. The melt- ing points given in the table serve to indicate the degree of purity of the products weighed. TABLE 11. --EtheriJimtion at 1 OOO. Proportion8 :-Naphthol : ethyl alcohol : sulphuric acid = 2 : 2 : 0.8 grams. No. of experi- ment. 1 2 3 4 5 6 7" 8 9 10' 11* 12 13 14* 15* 16 17 18 19 20 21 22 Naphthol. B- Naph thol ........................ I , ........................ Y ? ........................ I > Y 9 ................................................ 3'-Bromo-2-naphthol ........... 1 -Bromo-2-naphthol ............ Y ) ,, ........... ,, .......... l.C~loro-2-naphthol ........... ) ? JY 9 , ,, ........... ,) ........... 3, .......... 1 : 3'-Dibromo-2-naphthol. .... 1 -Chloro-3'-bromo -2-naphthol , I Y , ), ........... , , .......... , Y 2 9 , I * 1 : 3-Dichloro-2-naphthol ..... 1 . Nitro-2 -naph thol .............. l-Nitro-3-chloro-2-naphthoI . . 1 : 3 : 4-Trichloro~2-naphthol.. - Tjmc hours 111 24 3 t 11 2 20 15 20 6 t 6 i 159 20 25 11 20 16 20 20 20 20 164 64 - ~ Percentage yield of ether. 73'6 83'9 90.5 91'2 S9'1 88.7 3 '2 15'2 17.0 0-5 2 '1 9*3 8 '4 0.36 1*3 6.0 0.0 1.9 0.0 0.0 0 ' 0 0.0 M.p. of product weighed. 37-38" 37 ,, ?, ?9 62-64 62-64 63-64 55-56 55-56 56 56 - 82-85 84-86 67-76 - - - ...- M.p. of pure ether. 37'5" 37.5 9 , 9 , ? ¶ 80 66 66 66 58 3 ) ? ) Y , 94 9 3 ii 77 104 - - - I n the experiments marked *, the mixture was heated in boiling water ; in all others, the steam-bath was used.DAVIS : E'L'H 1CRIFICA'l'ION OF' DERIVATIVES OF B-NAPHTHOL. 37 TABLE 111.--Methylation at IOOO. I'y*oportions : Napht,hol : methyl alcohol : siilpliiit-ic acid = 2 0 : 2.0 : 0.8 grams. No. of experi- ment. 1 2 3 4 5 6 7 8 9 10 11 Naphthol. B-Naphthol.. ....................... ,, ......................... ,, ......................... 1-Rromo-2-naphthol ............ 3'-Broino-2-naphthol ............ Y 9 ,, ............ 9 9 ,, ............ 1-Chloro-2-naphthol ........... 1-Nitro-2-uaphthol .............. 1 : 3'-Dibroino-2-naphthol ......1 : 3'-Chlorobromo-2-naphtl1ol - Time in hours. 20 20 20 20 20 182 20 9 9 9 , $ 9 9 9 - Percen t a g yield of ether. 91 *15 95'9 91.3 21 *2 22 '4 98 -7 9 i -1 7 -45 5-4 0.0 0.0 M.p. of product weighed. 71-72" 7 1 71-72 80 104 104 60 73-76 80-81 - - M.p. of pure ether. 72' 72 72 82-83 82-83 105 105 68 100 126 - TABLE IV.--Propglation at looo. Proportions :-Naphthol : propyl alcohol : sulphuric acid = 2 : 2 : 0.8 grams. No. of experi- men t. 1 2 3 4 5 6 7 8 9 10 11 12 13 Naphthol. Time in hours. I- &Naphthol, ....................... 3'-Bromo-2-naphthol ............ 1-Bromo-2-naphthol .......... , , ......................... 9 , , , ........... 9 9 ,, ............ 1-Chloro-2-naphthol ............ I , ,, ............I 1 : 3'-Dibromo-2-naphthol.. ....7 ) ,, ............ l-Chloro-3'-bromo-2-naphthol. 1 : 3-Dichloro-2-naphthol.. ..... l-Nitr0-2-naphthol.~. ............ 12 20 20 20 20 20 20 20 16 20 20 20 20 Percentag yield of ether. 94 -5 93 *3 93 -8 92'0 12-7 12'9 0.75 0 *o 2.8 0.58 0'0 0 '0 de M.p. of product weighed. 38" 37-38 62 62 29 25-28 oil 45", dirty ompositj 56 - - - M.p. of pure ether. 39.5" 39.5 63.5 63-5 35-36 9 9 - - 75 60.5 n - - P-N'phtAyE Methyl Ethers. 3'-Bromo-2-methoxynaphthaZene, C,,H6Br*OMe, prepared by heating R mixture of 5 grams of 3'-bromo-2-naphthol (Armstrong and Davi?, Proc., 1896, 12, 231) and 5 grams of methyl alcohol during 10 hours at looo, is sparingly soluble in alcohol, moderately so in benzene, ethyl38 DAVIS : ETHERIFICATION OF DERIVATIVES OF ,&NAPHTHOL.acetate, chloroform, or acetone, and crystallises from acetic acid in balls of small, white needles; it melts at 105". 0.2342 gave 0.1875 AgBr. C,,H,OBr requires Br = 33.74 per cent. 1 -Bromo-2-methoxynup?~t?~a~ene, CIoH6Br* OMe, was prepared by heating 4 grams of 1-bromo-2-naphthol with 2.7 grams of methyl iodide, 1.4 grams of potassium hydroxide, and 10 grams of methyl alcohol during 5 hours in a sealed tube at 100'; it crystallises best from light petroleum, forms t h h , lustrous plates, and melts at 82.5'. Br = 34.07. 0,1643 gave 0.1290 AgBr. Br = 33.42. CllH,OBr requires Br = 33.74 per cent. 1 -ChZoro-2-rnethoxynap7~thaZene, C,,H6C1* OMe, prepared in a similar manner, crystallises from alcohol in thin, colourless plates, and melts a t 68'. 0.2100 gave 0.1571 AgC1.C1= 18-50. C,,H90Cl requires Cl = 18.41 per cent. 1 : 3'-Dibron~o-2-snethoxynaphthalene,CloH,Br,~OMe.-When 5 grams of I : 3'-dibromo-2-naphthol are heated with 2.5 grams of methyl iodide, 1.4 grams of potassium hydroxide and 12 grams of methyl alcohol in a s6aled tube during 6 hours at loo', a portion of the naphthol is not acted on, and only about 50 per cent. of the theoretical quantity of 1 : 3'-dibromo- 2-methoxynaphthalene is obtained ; it crystallises best from alcohol in small, nearly colourless plates and melts at 1009 0,1316 gave 0,1552 AgBr. C,,H,OBr, requires Br = 50.62 per cent. 1-ChZoro-3'- bromo-2-methoxynnp?~thaZene, CloH,CIBr*OMe, prepared in a similar manner from 1 -chloro-3'-bromo-2-naphthol, crystallises from hot alcohol in thin, colourless plates, which are at first transparent, but become slightly opaque as the solution cools, possibly owing to a change in crystalline form ; i t melts at 92.5'.Br = 50.20. 0.1428 gave 0.1747 AgCl + AgBr. AgCl + AgBr = 122.33. Cl1H,OC1Br requires AgCl + AgBr = 3 22.00 per cent. P-NaphthyZ Ethyl Ethers. l-Bromo-2-ethoxyn~pht~~a~n~,CloH,Br.OEt, is best prepared by adding bromine (1 mol.) drop by drop t o a solution of P-ethoxynaphthalene in glacial acetic acid, but is also formed by ethylating 1-bromo-2-naphthol; it crystallises from light petroleum in colourless plates and melts at 66".DAVIS : ETHERIFICATION OF DERIVATIVES OF @-NAPHTHOL. 39 3‘-Bro,,io-2-etho~L.ytici2,?~thuZeiie, C,,H,Br*OEt, is best prepared by heating n mixture of 5 grams of 3’-bromo-2-naphthol, 5 grams of ethyl alcohol, and 2.0 grams of sulphuric monohydrate during 6 hours at 100’ ; i t crystallises from alcoliol in colourless plates, melts at SOo, and is easily soluble in benzene, acetic acid, chloroform, ether, ethyl acetate, or light petroleum. 0.1382 gave 0.1041 AgBr.C,,H,,OBr requires Br = 31.88 per cent. On one occasion, a mixture of 20 grams of 3’-bromo-2-naphthol with 20 grams of ethyl alcohol and 8 grams of sulphuric acid was, by an oversight, boiled more vigorously than was intended, and nearly the whole of the alcohol evaporated; as a consequence a considerable quantity of 3’-bromo-2-naphtholdisulphonic acid (Arm strong and Davis, Proc., 1896, 12, 231) mas formed. On removing this by adding water, a small quantity of a heavy oil remained undissolved; on washing this with a little alcohol, it solidified to a dark, greyish powder.Ths alcoholic washings were poured into water and the precipitate obtained crystallised from light petroleum containing a small quantity of benzene, when small, colourless needles separated melting a t 125” ; these were insoluble in aqueous caustic soda and therefore did not consist of unchanged 3’-bromo-Z-naphthol, which melts a t 12’i0, but the quantity of substance obtained was insufficient to determine its nature by an analysis. The greyish powder left undissolved by the alcohol was crystallised from glacial acetic acid ; it separated in colourless plates melting a t 169’ to a deep red liquid ; after crystallisation, it became very sparingly soluble in glacial acetic acid and was insoluble in aqueous caustic soda.On analysis, the following numbers were obtained : Br = 32.05. 0.2140 gave 0.1813 AgBr. 0.2768 ,, 0.2327 AgBr. Br=35.79 ,, Br = 36-06 per cent. These results and the properties of the substance suggested that it was somewhat impure di-3’-bromo-2-naphthyl ether, ( CloH6Br),0. The quantity of substance obtained, however, was so small as to pre- clude further purification, but the view as t o its nature was con- firmed by a comparison with the dinaphthyl ether, Di-3‘-bromo- 2-nczphthyl etheris prepared by boiling 2 grams of 3’-bromo- 2-naphthol with 30 grams of 50 per cent. sulphuric acid during 12 hours in a reflux apparatus; the yield in these circumstances is small, most of the naphthol being recovered unchanged ; it crystallises from glacial acetic acid in colourless plates and melts at 170-171’, the melting point being unchanged by mixing it with the substance melting a t 169” which was believed to be identical with it,40 DAVIS : ETHEKIFICATION OF DERIVATIVES OF P-NAPHTHO L.0.0954 gave 0.0824 AgBr. C,,H120,Br2 requires Br = 37.22 per cent. l-ChZoro-2-ethoxynapl~t?~at?ene, CloH,C1*OEt, prepared by heating 1-chloro-2-naphthol (2 grams) with ethyl bromide (1.3 grams), caustic potash (1.0 gram), and absolute alcohol (12 grams) during 3 hours a t 1 OO", crystallises from alcohol in beautiful, colourless leaflets and melts at 58'; it is easily soluble in benzene or light petroleum, and very soluble in chloroform, ethyl acetate, or acetone. Br = 36.86. 0-2051 gave 0.1414 AgCl.C,,H,,OCl requires C1= 17.17 per cent. 1 : 3' : Dibromo-2-ethoxynaphthalene, CloH,Br2*OEt, is best prepared by gradually adding bromine (2 mols.) to @-cthoxynaphthalene dis- solved in four times its weight of glacial acetic acid, and subsequently warming a t 100'; it crystallises from light petroleum in beautiful, lustrous needles and melts at 94'. Its structure follows from its being formed when 1 : 3'-dibromo-2-naphthol is heated with the theoretical quantity of ethyl bromide and caustic potash in absolute alcohol during 5 hours at 100'. C1= 17.04. 0.1540 gave 0.1756 AgBr. C12HloOBr2 requires Br = 48.49 per cent. 1 -Chloro-S'- brorno-2-ethoxyaapl~thaZene, Cl,H,C1 Br OE t, obtained by heating l-chloro-3'-bromo-2-naphthol with ethyl bromide (2.5 grams), sodium hydroxide (1 gram), and absolute alcohol (15 grams) in a sealed tube for 6 hours at loo', crystallises from alcohol or light petroleum in thin, colourless, lustrous, elongated plates and melts at 77.5'; it is very soluble in benzene, chloroform, ether, acetone, or ethyl acetate.Br = 48.52. 0.1 829 gave 0.21 30 AgCl + AgBr. AgCl + AgBr = 1 16.5. C,,H,oOCIBr requires AgCl + AgBr = 116.1 per cent. P-Naphthyl Prop$ Ethers. @-Propoxynaphthalene, according to Bodroux (Compt. Tend., 1898, 126, 840), is formed on heating @-naphthol with propyl iodide and alcoholic potash, but it is best prepared by gently boiling a mixture of P-naphthol (10 grams), propyl alcohol (10 grams), and sulphuric monohydrate (4 grams) during 6 hours. It crystallises best from alcohol in long, colonrless needles, and melts at 39%' as stated by Bodroux. 3'-Bromo-2-propoxynaphthalene, CloH6Br*OPra, prepared in the same manner as P-propoxynaphthalene, crystallises from hot iLlcoho1 in beautiful, thin, transparent plates ; before crystallisation is corn-DAVIS : EC'HERIFICATION OF DEltIVnTlV ES OF B-NAPHTHOL.41 plete, nowever, white, opaqne balls of needles form, whilst these alone are obtained if the ,?mount of alcohol used has been sufficient to prevent crystallisation commencing until the solution has cooled to the atmospheric temperature. The transparent crystals apparentIy contain alcohol of crystallisation, but this is lost so mpiclly on exposure to the air that its amount could not satisfactorily be deter- mined ; when the plates are exposed to the air for 6 days, they crumble to powder, and are then free from alcohol, as the following analysis indicates : 0.2051 gave 011456 AgBr.Br = 30°21. C,,H,,OBr requires Br = 30.18 per cent. The pure snbstance melts at 6305'~ but after solidification melts quite sharply at 56' (three determinations), although after 36 hours the melting point has again risen to 63.5'; i t crystallises from glacial acetic acid or light petroleum in small, globular aggregates of whit'e ceedles and is very soluble in chloroform and ether. 1-B.r~omo-2-popoxync~phtl~alelze, CloH,Br*OPra, is best obtained by adding bromine (1 mol.), dissolved in an equal quantity of glacial scet,ic acid, drop by drop to a cooled solution of @-propoxynaphthalene in glacial acetic acid ; an oil separates which is washed with water and caused to solidify by surrounding it with ice; on crystallising from alcohol, nearly colourless, small, prismatic flakes are obtained melting a t 35-36'.It is also formed on heating 1-bromo-2-naphthol with propyl bromide (6 grams), ca.ustic potash (2.3 grams), and propyl alcohol during 5 hours a t loo', but the yield is poor (compare 1 : 3'-dibromo-2-propoxynaphthalene). 0-2032 gave 0.1428 AgBr. Br = 29.85. C,,H,,OBr requires Br = 30.18 per cent. 1 : 3'-Dibvomo- 2-propoxynupht?Lalene, CI,H,Br,*OPr", is best obtained by gradually adding 2 mols of bromine to /I-propoxynaphthalene dissolved in glacial acetic acid; it crystallises from alcohol in well-defined, slightly yellow prisms and melts a t 78". When 1 : 3'-dibromo- 2-naphthol (7.5 grams) is heated with propyl bromide (3.0 grams), caustic potash (2*3grams), and propyl alcohol (20 grams) in a sealed tube during 7 hours at 100°,a considerable proportion of the naphthol is not acted on, a portion is decomposed, giving rise to resinous products, and the yield of ether is small.0.1032 gave 0.1134 AgBr. C,,H,,0Br2 requires Br = 46.50 per cent. l-Chlo~*o-3'-bromo-2-popoxynaphthal~ne, C,,,H5CIBr*OPr,, obtained from l-chloro-3'-bromo-2-naphthol by the propyl bromide method, Br = 46.77.42 DSVIS : EFHlCRlF[rlATI9N OF DERIVATIVES OF @-NAPHTHOL. cryst;illises from alcohol, in which i t is moderately soluble, in large, nearly colourless, very thin plates, and melts a t 60.5.’ ; on analysis : 0.1848 gave 0.2050 AgCl + AgBr. AgCl + AgBr = 110.9.C,,H,,OClBr requires AgCl + AgBr = 110.6 per cent. BiscussioI~ of Iiesults. The results tabulated on pages 35-37 serve to show that a single halogen atom in position 1, contiguous to the hydroxyl group of @naphthol, has a most remarkable effect in limiting etherification, the effect being least in the case of methyl and greatest in that of propyl alcohol. Chlorine has an even greater effect than bromine, and n nitro-group in position 1 entirely prevents etherification. That the position of the halogen is the main determining cause of its influence is clearly brotight out by the fact that 3’-bromo-F-naphthol is etherified as easily as the unbrominated naphthol, but it will be seen that, on introducing bromine into position 3’ in either l-chloro- or l-bromo-@naphthol, the production of ether is considerably diminished.These results stand in striking contrast to those obtained in the well-known experiments made by Victor Meyer and Sudborough, since extended by others,” on the etherification of substituted benzoic acids. I n the case of benzoic acid, a single group in the ortho- position has little influence, whereas two such groupp, iF they do not altogether prevent etherification (01, Br, I, NO,), greatly affect either the rate a t which it takes place or its extent (CH,, OH, F). Victor Meyer has sought to find an explanation of these facts in stereo- chemical considerations, and has regarded the influence exercised by various radicles as dependent on their volume; but, strange to say, he has taken mass as the measure of volume.? Such a hypothesis appears to be by no means justified by facts.Thus the order of inhibitive influence of different radicles on the formation of ethereal salts of ortho-substituted benzoic acids appears from Kellas’ results to be C1, CH,, Br, I, NO,; but the order of the relative weights is CH,, C1, NO,, Br, I, and that of atomic volumes, CH,, 01, Br, NO,, I (Graham-Otto, I, 3, 449), or according to Traube (Alzncclelz, 1896, 290, 43) C l = B r = I (13~2)~ OH, (19.2), NO, (20). From Goldschmidt’s values for the velocity coeflicients, the radicles * V. Meyer and Sudborough, Ber., 1891, 27, 510, 1580, 3146 ; Lepsius, ibid., 1635 ; V. Meyer, Ber., 1895, 28,182, 1254, 2773, 3197 ; 1896, 29, 830, 1397 ; van Loon and V. Meyer, ibid. , 839 ; Golduchmidt, Ber., 1895, 28, 3218, Kellas, Zeit. plzysi- kal.Chem., l897,24, 221 ; Wegscheider, Monatsh., 1895,16, 75 ; Ber., 1895,28, 1474, 2535 ; Monatsh., 1897, 18, 629 ; Sudborough and Feilmann, Proc., 1897, 13, 241. For a discussion of this point, see V. Meyer, Ber., 1895, 28, 126 ; 1896, 29, 843 ; Wegscheider, Ber., 1895, 28, 126, Monatslb., 1897, 18, 635.DAVIS : ETH ERIFICATION OF DERIVATIVES OF &NAPHTHOL. 43 should stand, as regards retarding influence, in the order Br, C‘H,, NO,, but in the case of the naphthyl ethers, the order appears from my results to be Br, C1, NO,. So that the observations of Goldschmidt and of Kellas, as well as my own, are in accord neither with the arrange- ment by atomic weights nor with that by atomic volumes ; consequently, there appears to be a factor governing the etherification of both carboxylic acids and phenols * of which we are a t present in ignorance.Even if we consider, as Mudborough and Feilmann have suggested that the etherification is determined by two factors, (1) the stereochemical influence of the configuration, (ii) the strength of the acid as measured by its affinity constant, we are brought no nearer to an explanation of the extraordinarily great inhibiting influence of a nitro-group compared with that of other groups.? Wegscheider (Monntsh., 1895, 16, 75, and 1897, 18, 629) has given reasons for considering that, in the etherification of carboxylic acids under the influence of alcohol and concentrated sulphuric acid or hydrogen chloride, an intermediate compound is formed by addition t o the carboxyl group, as was originally assumed by Henry (Ber., 1877, 10, 204l), and later work has strengthened this hypothesis (compare Lloyd and Sudborough, Trans., 1899, 75, 580); he has suggested that phenols undergo etherification in a somewhat similar * Sudborough and Lloyd (Trans., 1899, 75, 467, 580) give a bibIiographyof papers dealing with the influence of ortho-substituted groups on the etherificatioii of acids, the hydrolysis of ethereal salts, and of acid chlorides, amides, and nitriles ; the results obtained by Kdster and Stallberg (AnnitZen, 1894, 278, 207) belong t o the same category.Contiguous groups also exert au important influence on the preparation of oxiines and phenylhydrazones of aromatic aldehydes and ketones (Kehrmann, Ber., 1888, 21, 3315 : 1694, 27, 3344 ; J.pr. C l ~ m . , 1890, [ii], 40, 257 ; Hantzsch, Ber., 1890, 23, 2769 ; Feith and Davies, Ber., 1891, 24, 3546 ; Petrenko-Kritschenko, Ber., 1895, 28, 3203 ; Bauin, Ber., 1895, 28, 3207, V. Meyer, Ber., 1896, 29, 830) ; the formation of imido-ethers from nitriles (Pinner, Ber., 1890, 23, 2917) ; and many other more complex interactions (compare Busch, J. yr. Chm., 1895, [ ii], 51, 113 ; 52, 273; 1896, 53, 414 ; lS97,55, 356; Jacobson, Annctlen, 1895, 287, 118 ; 1898, 303, 290 ; Ber., 1898, 31, 890 ; Anschutz, Rer., 1897, 30, 221 ; Bischoff, Ber., 1897, 30, 2478, 2772 ; 1898, 31, 3324 ; Scholtz, Ber., 1898, 31, 414 and 627 ; 1899, 32, 2261 ; Wedekiiid, Ber., 1898, 31, 1746 ; Friedlander, Monatsh., 1898, 19: 627 ; Paal and Schilling, J.pr. Chem., 1896, [ii], 54, 277 ; Paal and Benker, Ber., 1899, 32, 1251 ; Paal and Hartel, ibid., 2057). The presence of ortho-alkyl groups in aromatic ketones and ketonic acids also determines very largely the behaviour of these compounds on hydrolysis (Louie, Ann. Chirn. Phys., [vi], 1885, 6, 206 ; Elbs, J. pr. ChenL., [ ii], 1887, 35, 465 ; V. Meyer, Ber., 1895, 28, 1270 ; Muhr, ibid., 3215, and Weiler, Ber., 1899, 32, 1908). Victor Meyer, in discussing the atomic volume value, suggests “dass das Estergesetz uns ein Mittel in die Hand gebe die relative Raumerfullung der Atoine in den organischen Verbiiidungen mit einaiider zu vergleichen.” The varying in- hibiting influence of the same clement in acids and in phenols seems to preclude the acceptance of this suggestion.44 DAVIS : ETHEltIF'lCATLON O F DERIVATIVES OF 6-NAPRTHOL.manner, and that initially they give rise to keto-dihydro-derivatives (Monatsh., 1895, 16, 140). According to this view, P-naphthol would he first converted into the componnd H" and on losing water this would yield P-ethoxynaphthalene. Evidence to a certain extent in favour of this view may be found in the behaviour of @naphthol in contrast with that of phenol. Experiments made by Mr. Panisset, at Dr. Armstrong's suggestion, show t h a t phenol and parabroruophenol may be partially etherificd by means of alcohol and sulphuric acid, but that they yield at most about 25 per cent. of ether. Inasmuch as benzene and its derivatives are less prone to form additive compounds than are naphthalene and its derivatives, and the former are generally less readily attacked than the latter, the fact that phenol is less readily etherified than naphthol is in accordance with the view that addition precedes substitution (compare Armstrong, Trans., 1887, 51, 258 ; Armstrong and Rossiter, Proc., 1891, 7, 89).Now if benzene is represented by KekulB's formula, it is a matter of indifference on which side of a CO,H group the double linking is placed, but i t is not unlikely that, in bromobenzoic acid, for example, it is between the iinbrominated carbon atoms, so that there is a n active ethenoid linking in the immediate neighbourhood of the carboxyl. But it may well be that in P-naphthol no such shift can take place, and t h a t when the linking between positions 1 and 2 is rendered comparatively inactive by the introduction of a.radicle into position 1, the combining power of the compound is greatly reduced. Victor Meyer's observations on the etherifkittion of 2-chloro- or 2-hydroxy-1-naphthoic acid and of 3-chloro- and 3-hydroxy- 2-naphthoic acid are equally in accordance with this view : the former are not attacked whilst the latter are readily etherified. There can be no doubt that 1-derivatives of 2-naphthoic acid will prove equally unsusceptible. Although the structure of the nucleus has a distinct influence, i t would appear that it is rather the specific attracting power of the radicle which is eventually etheritied that becomes affected and diminished by the introduction of negative radicles into the nucleus in its neighbourhood.Armstrong, indeed, has suggested this in ex- planation of the phenomena, observed by Victor Meyer, and has pointed out (Proc., 1896, 12, 42) that '' the formation of a salt is presumably preceded by that of a combination of acid and ' alkaloid,' from which water is then eliminated. J u s t as the acid attractingJAPACONITINE AND THE ALKALOIDS OY JAPANESE ACONITE. 45 power of theNH, radicle in aniline is affected by the introduction, say, of chlorine, so in like manner, the ‘ alkaloid ’-attracting power of the carboxyl group may be assumed to vary as radicles are introduced in its neighbourhood in place of the hydrogen, more particularly in the case of benzenoid compounds.” Whatever the ultimate explanation of the behaviour of benzenoid acids and phenols, there can be little doubt that the phenomena of etherification must be viewed from the same standpoint as those of substitution generally, as there is complete parallelism between them. Armstrong has recently called attention (Proc., 1899, 15, 176 ; Chew. News, 1899, 80, 164) to the effects produced by introducing alkyl radicles in place of the hydroxylic and aminic hydrogen in phenols and smines, and to the remarkable manner in which the formation of sub- stitution derivatives is inhibited. It is clear, in fact, that the influence of radicles in the nucleus on etheritication, and, on the other hand, of etherification on the occurrence of substitution in the nucleus is reciprocal. This is further shown to be the case by the difference in the influence exercised by radicles according t o their position-a single radicle in the meta-position relatively to the carboxyl of benzoic acid exercising less influence on the rate of etherification by alcohol and hydrogen chloride than does the same radicle in the para-position and much less than it does in the ortho-position. It is impossible t o overlook the parallelism which such facts present with the phenomena of substitution expressed iu the well-known “ ortho-para ” and “ meta ” laws. CHEMICAL DEPARTMENT, CITY AND GUILDS OF LONDON IKSTITUTE CENTRAL TECHNICAL COLLEGE.