On this page
Every coloured T-shirt depends on chemistry that someone had to work out molecule by molecule. In India, one of the people who built that chemistry into a research field, and into institutions, was Krishnasami Venkataraman. Organic chemistry students meet his name in a reaction, the Baker-Venkataraman rearrangement. This post covers his career, his work on dyes, and the reaction itself with a worked example you can check.
Who was K. Venkataraman?
The official list of former directors of CSIR-National Chemical Laboratory, Pune, gives the outline. He was born in 1901 and took his PhD and DSc at the University of Manchester under Sir Robert Robinson, later a Nobel laureate. He joined Forman Christian College in Lahore in 1929. In 1938 he became director of the University Department of Chemical Technology in Bombay. Before he took charge of the National Chemical Laboratory he had already served on its planning committee and on the committee that chose its site. He was NCL's director from 1957 to 1966, the first Indian to hold the post.
Our post on Robert Robinson and the tropinone synthesis describes the laboratory he trained in.
What was The Chemistry of Synthetic Dyes?
It was a multi-volume reference work by Venkataraman, published by Academic Press. A 1953 review in Angewandte Chemie notes that volume II, published in 1952, ran from page 705 to page 1442, so the first two volumes alone came to more than 1,400 pages. The series kept growing: Crossref lists his preface to volume VIII, dated 1978, and chapters such as one on anthraquinonoid vat dyes written with V. N. Iyer for an earlier volume.
Synthetic dyes began with William Perkin's mauve in 1856, covered in our post on Perkin and the first synthetic dye. A century later the field had become large enough to need a multi-volume map, and Venkataraman drew it.
What is the Baker-Venkataraman rearrangement?
In 1933 Baker published a paper on the molecular rearrangement of some o-acyloxyacetophenones, and in 1934 H. S. Mahal and K. Venkataraman published Part XIV of their series on chromone synthesis, on the action of sodamide on related esters, both in the Journal of the Chemical Society. The reaction now carries both names.
A 2026 paper in RSC Advances shows how chemists still use it. An ester of an o-hydroxyacetophenone is treated with a base (they used potassium hydroxide in pyridine). An intramolecular Claisen condensation moves the acyl group from the oxygen to the carbon next to the ketone, giving a 1-aryl-3-(2-hydroxyphenyl)propane-1,3-dione. Heating that diketone with acid closes a ring and removes water, giving a chromone.
Worked example: following the atoms to flavone
Use the simplest case, which ends in flavone, the parent compound of a large family of plant pigments. Molar masses are from PubChem.
Make the ester. 2'-hydroxyacetophenone (C8H8O2, 136.15 g/mol) reacts with benzoyl chloride (C7H5ClO, 140.56 g/mol), losing HCl (36.46 g/mol). The ester is 2-acetylphenyl benzoate, C15H12O3. Check: 136.15 + 140.56 − 36.46 = 240.25 g/mol, and PubChem lists 240.25.
Rearrange. Base turns the ester into 1-(2-hydroxyphenyl)-3-phenylpropane-1,3-dione. PubChem lists it as C15H12O3, 240.25 g/mol: the same formula, as the callout says.
Close the ring. Acid removes one water molecule (18.02 g/mol) to give flavone, C15H10O2. Check: 240.25 − 18.02 = 222.23, against PubChem's 222.24. The difference of 0.01 is rounding.
Counting atoms at each step is a quick test of whether you have the mechanism right. If your product has a different formula after step 2, something has gone wrong.
Common mistakes:
Thinking the base adds something to the molecule. In step 2 it removes a proton to start the reaction and gives it back; the product is an isomer.
Losing track of which carbon is attacked. The new carbon-carbon bond forms at the CH3 next to the ketone, which is the carbon the base deprotonates.
Forgetting that ring closure is a condensation. A small molecule, here water, has to leave.
How does this connect to dyes in your syllabus?
Most synthetic dyes you meet in Class 12 are azo dyes, made by coupling a diazonium salt with a phenol or an aromatic amine. Our guide to amines and diazonium salts works through those reactions. Venkataraman's reference books covered the whole range, from azo dyes to vat dyes like the anthraquinone ones above.
What can a student take from Venkataraman?
His career joined three things that are often kept apart: reaction mechanisms, a large industrial subject, and the building of research institutions. For a student the useful habit is the one in the worked example. Whenever you meet a named reaction, write the formula of every species and check that the atoms balance before you memorise anything.
If a named reaction still looks like a list of steps without a reason, the Fermi Concept Library covers every concept in physics, chemistry, biology, mathematics and computing, so you can revisit carbanions or condensation reactions on their own.
Try it now: start from 2'-hydroxyacetophenone and acetyl chloride instead, and work out the molecular formula of the ester, the diketone and the final chromone.
