SWiM has a nice collection of books, viz Meyer's Synthese der Kohlenstoffverbindungen. It's a collection of prepartion methods, described very shortly, with references to the original publications. Here are the data for benzaldehyde:
1) 100 g benzene + 45 g AlCl3, HCl, 40-50°c + CO for several hours. Pressure is 90 atm. Yield: 30 g --- 100 g AlCl3, 1 g TiCl4, 190 g benzene, 30-40°C + CO till 60 atm. [1,2]
2) 60 g benzene, 60 g AlBr3, 12 g CuCl2 + CO, HCl (2:1), first cool down with water, then 5h at 20°C. Yield: 90%. Or with AlCl3, Cu2Cl2, 7 hours at 45°C + CO, HCl [3,4]
3) 4 mol benzene, 1 mol Ni-carbonyl, 4 mol AlCl3, stand for several days. Add water. Yield: 20% [5].
4) 150 g benzene, 90 g Hg 43-45°C in 40 min + 120 g AlCl3, 15 g AlCl3 + 6 H2O, 15 g Al(OH)3. Stand for 3h. Yield: 68% oxime + 1.2 g aldehyde [6].
5) PhMgBr, ether + HCOOH or 3 mol formic acid ester -50°C. Better is + 1/2 eqv ortho-formic acid. Yield: 93% [7,8,9].
6) 6 g PhMgBr, ether, 2 g methylcarbylamine, ether 0°C stand for 12 hours. Or + methylformanilide, or + ethoxymethyleneaniline, boil shortly. Yield: 46% [10,11,12].
7) benzene, HCl, HCN, AlCl3, 100°C [13].
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1 DRP 281212
2 EP 334009
3 GATTERMANN, Ann 347 (1906) 351
4 HEY, J Chem Soc London (1935) 72
5 DEWAR, JONES, J Chem Soc London 85 (1904) 213
6 SCHOLL, Ber 32 (1899) 3498
7 ZELINSKY, Chem Ztg 28 (1904) 304
8 GATTERMANN, MAFFEZZOLI, Ber 36 (1903) 4152
9 WOOD, COMLEY, J Chem Soc Ind 42 (1923) 429
10 SACHS, LOEVY, Ber 37 (1904) 875
11 BOUVEAULT, Bull Soc Chim France (3) 31 (1904) 1327
12 MONIER, WILLIAMS, J Chem Soc London 89 (1906) 275
13 HINKEL, AYLING, J Chem Soc London (1932) 2793
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SWiM added this to "complete" the library of benzaldehyde synthesis possibilities. As you see, all routes start with benzene or PhMgBr. The brevitas is typical for Meyer's work. If you want to know more about a particular method, you have to look up the mentioned references.
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