Based on biogenetic considerations new syntheses of menaphthone and lawsone are given. Fromα-naphthol, 1-hydroxy-4-methoxy-2-naphthaldehyde is prepared. This undergoes Clemmensen reduction and subsequent oxidative demethylation with nitric acid to yield menaphthone. On the other hand, Dakin’s oxidation gives directly lawsone and this change involves oxidative demethylation by hydrogen peroxide in alkaline solution. A convenient laboratory method for preparing lawsone employs 2-acetyl-α-naphthohydroquinone.

The methyl ethers of morin, resomorin and resodatiscetin have been made by different methods in order to examine the possible resistance of the 2′-hydroxyl group to methylation. No such resistance is found. 8-Hydroxy derivatives of morin, datiscetin and resodatiscetin have been prepared by employing methods of nuclear oxidation.

Partial methyl ethers of chrysin, apigenin, galangin and quercetin have been subjected to nuclear reduction in the 5-position through their tosyloxy compounds. The products are 7-methoxy flavone, pratol methyl ether, 3:7-dimethoxy flavone and fisetin tetramethyl ether respectively.

By the application of nuclear reduction a quercetin derivative has been converted into kæmpherol and a kæmpherol derivative into galangin.

Nuclear reduction of 7-hydroxy and 5-hydroxy flavones yieldsβ-4-hydroxy flavan whereas 3-methoxy-7-hydroxy flavone yields 3-methoxy flavone. The pyrone ring escapes further reduction if there should be a substituent.

3-Methoxy-7-hydroxy flavone does not undergo nuclear methylation. Nuclear methylation of (1) 3-O-methyl galangin and (2) 3:4′-O-dimethyl kaempferol has been shown to take place in the 6-position. As an intermediate in the case of (1) 3-O-methyl-6-C-methyl galangin has been isolated. The minimum structural requirements of this reaction and its mechanism are discussed.

Nuclear methylation of phloracetophenone and 3-C-methyl phloracetophenone, under vigorous conditions yields 5-acetyl-1∶1∶3∶3-tetramethyl cyclohexen-(4)-ol-(4)-dione (2∶6) (III); the intermediate 3∶5-dimethyl compound could not be obtained. This method is convenient for the preparation of leptospermone (VI). Many natural products seem to be formed by the nuclear methylation of the carbonyl derivatives of phloroglucinol. Using lesser proportions of alcoholic potash lower methylation products are obtained; but 3∶5-dimethyl-phloroacetophenone could be isolated only in small quantities.

Nuclear methylation of 2:4-dihydroxy-chalkones (III) give rise to 3-C-methyl derivatives just as in the case of resacetophenone. C-Methylchalkone-derivatives (IV) with substituents in the side phenyl nucleus have also been prepared by this method. For comparison, they have been synthesised using 3-methyl-peonol and appropriate derivatives of benzaldehyde. C-Methyl-iso-liquiritigenin-dimethyl-ether (IVb) was cyclised to the corresponding 8-methyl-flavanone (VI).

The flavanone, naringenin, when subjected to nuclear methylation under mild conditions yields 6-methyl-flavanone derivative (VIII) whereas under conditions in which the oxygen ring opens, beside the above 6-methyl flavanone (VIII), poly-C-methylated chalkones (XIIa+b) are formed just as in case of phloracetophenone.

In this paper we have discussed the boundary layer on a plate with suction. The problem is solved near the leading edge as well as far downstream. A linear suction law is assumed near the leading edge for simplicity, whereas no restriction is placed on the suction law in the region downstream. An explict expression for boundary layer thickness in terms of suction speed and distance from leading edge is derived. It is found that the thickness of the boundary layer depends on the derivative of the suction speed. The skin friction also has been evaluated. Though near the leading edge a linear law of suction is assumed, the method used in the paper can be easily generalised for any other power law, for example, we may use a power series expansion for the function defining the suction velocity.

A quartic profile in terms of the normal distance from the wall has been taken and coefficients are evaluated by satisfying one more boundary condition on the wall than the usual one. By doing so, the limitations about the Reynolds number of the quartic profile adopted by Lew (1949) has been removed. The Kármán (1921) Momentum Integral Equation has been used to evaluate the various characteristics of the flow. A comparative study of Lew’s quartic profile and exponential profile together with the quartic profile of the present paper has been undertaken and the graphs for the various characteristics of the flow for a number of Mach numbers and suction coefficients have been drawn. At the end, certain conclusions of general nature about the velocity profiles have been recorded.

For the action of iodine and silver acetate on flavanones to take place, the nature and position of substituents are important. The presence of either a 5-hydroxyl or a 5-methoxyl is essential for any reaction to occur. A free hydroxyl in the 7-position is inhibitory even for iodination of 5-hydroxyflavanone derivatives. Complete methyl ethers yield 8-iodocompounds; whereas 5-hydroxy-7-methoxyflavanones afford a mixture of 3-iodo and 8-iodo derivatives. Simple 5-hydroxy-flavanone forms 3, 8-di-iodo and 2, 3-di-iodo-5-hydroxy flavanones. 5-Hydroxy-7, 4′-diacetoxy-flavanone undergoes iodination only in the pyranone part to yield 2, 3-di-iodo and 3-iodo derivatives; substitution in the benzene ring is inhibited. It is suggested that the 5-hydroxyl by chelation with the carbonyl increases the activity of the methylene group in the 3-position.