In a 500-ml round-bottomed flask pl

In a 500-ml round-bottomed flask place a mixture of 30 g (0.246 mol) of benzoic acid, 80 g (101 ml, 2.5 mol) of absolute methanol and 5g (2.7 ml) of concentrated sulphuric acid. Add a few small chips of porous porcelain, attach a reflux condenser and boil the mixture gently for 4 hours (1). Distil off the excess of alcohol on a water bath (rotary evaporator) and allow to cool. Pour the residue into about 250 ml of water contained in a separatory funnel and rinse the flask with a few ml of water which are also poured into the separatory funnel. If, owing to the comparatively slight difference between the density of the ester and of water, difficulty is experienced in obtaining a sharp separation of the lower ester layer and water, add 10-15 ml of carbon tetrachloride (2) and shake the mixture in the funnel vigorously; upon standing, the heavy solution of methyl benzoate in the carbon tetrachloride separates sharply and rapidly at the bottom of the separatory funnel. Run off the lower layer carefully, reject the upper aqueous layer, return the methyl benzoate to the funnel and shake it with a strong solution of sodium hydrogen carbonate until all free acid is removed and no further evolution of carbon dioxide occurs. Wash once with water, and dry by pouring into a small dry conical flask containing about 5 g of magnesium sulphate. Stopper the flask, shake for about 5 minutes and allow to stand for at least half an hour with occasional shaking. Filter the methyl benzoate solution through a small fluted filter paper directly into a round-bottomed flask fitted with a still-head carrying a 360 °C thermometer and an air condenser. Add a few boiling chips and distil from an air bath; raise the temperature slowly at first until all carbon tetrachloride has passed over and then heat more strongly. Collect the methyl benzoate (a colourless liquid) at 198-200 °C. The yield is 31g(92%).
Notes. (1) Slightly improved results may be obtained by increasing the time of heating. (2) Alternatively, the ester may be extracted with two 50 ml portions of ether. The ethereal solution is washed with concentrated sodium hydrogen carbonate solution (handle the separatory funnel cautiously as carbon dioxide is evolved) until effervescence ceases, then with water, and dried over magnesium sulphate. The ether is removed by flash distillation and the residual ester distilled. Cognate preparations. [The p.m.r. spectra (CDC13 or CC14, TMS) of the ethyl, propyl and butyl esters should be recorded and interpreted, since the signals corresponding to the protons of these alkyl groups, afford good examples of the (N + 1)(M + 1) rule for multiplicity (p. 341).]

Hasil (Bahasa Indonesia) 1:

Dalam 500 ml bulat-dipercaya labu Tempatkan campuran 30 g (0.246 mol) asam benzoat, 80 g (101 ml, 2,5 mol) dari metanol mutlak dan 5g (2.7 ml) dari asam sulfat pekat. Tambahkan beberapa chip kecil dari berpori porselen, melampirkan pendingin refluk dan mendidih campuran lembut selama 4 jam (1). Menyaring dari kelebihan alkohol pemandian air (rotary evaporator) dan biarkan dingin. Tuangkan residu ke sekitar 250 ml air yang terkandung dalam corong dan bilas labu dengan sedikit ml air yang juga dituangkan ke dalam corong. Jika, karena relatif sedikit perbedaan antara kepadatan Ester dan air, kesulitan yang dialami dalam memperoleh tajam pemisahan lapisan bawah ester dan air, tambahkan 10-15 ml karbon tetraklorida (2) dan kocok campuran dalam saluran keras; Berdasarkan berdiri, solusi berat metil benzoate dalam karbon tetraklorida memisahkan tajam dan cepat di bagian bawah corong. Lari lapisan bawah dengan hati-hati, menolak berair lapisan atas, kembali benzoate metil ke saluran dan kocok dengan kuat larutan natrium karbonat hidrogen sampai semua gratis asam akan dihapus dan lebih lanjut evolusi karbon dioksida terjadi. Cuci sekali dengan air, dan kering dengan menuangkan ke dalam labu berbentuk kerucut kering kecil yang berisi tentang 5 g dari magnesium sulfat. Stopper labu, kocok selama sekitar 5 menit dan memungkinkan untuk berdiri selama setidaknya setengah jam dengan kadang-kadang gemetar. Saring solusi benzoate metil melalui kecil kertas filter bergalur langsung ke bulat-dipercaya labu dilengkapi dengan kepala masih membawa termometer 360 ° C dan kondensor AC. Menambahkan beberapa mendidih keripik dan menyaring dari penangas udara; meningkatkan suhu perlahan-lahan di pertama sampai semua karbon tetraklorida telah melewati dan kemudian panas lebih kuat. Mengumpulkan benzoate metil (cairan) pada 198-200 ° C. Hasil adalah 31g(92%).Notes. (1) Slightly improved results may be obtained by increasing the time of heating. (2) Alternatively, the ester may be extracted with two 50 ml portions of ether. The ethereal solution is washed with concentrated sodium hydrogen carbonate solution (handle the separatory funnel cautiously as carbon dioxide is evolved) until effervescence ceases, then with water, and dried over magnesium sulphate. The ether is removed by flash distillation and the residual ester distilled. Cognate preparations. [The p.m.r. spectra (CDC13 or CC14, TMS) of the ethyl, propyl and butyl esters should be recorded and interpreted, since the signals corresponding to the protons of these alkyl groups, afford good examples of the (N + 1)(M + 1) rule for multiplicity (p. 341).]