musings on music and life

November 23, 2016

Dr. M. Balamuralikrishna

Filed under: Carnatic Music — sankirnam @ 12:54 am

I just heard the news today that the renowned musician Dr. Mangalampalli Balamuralikrishna passed away. I’m not referring to him as a “Carnatic vocalist” or “Carnatic musician” here, because his music transcends such classifications. My Facebook news feed today was full of people writing posts on this theme, and I figured I could write something a little longer here.

Dr. Balamuralikrishna (I’ll refer to him from here on as “BMK”) was probably the first Carnatic musician (!) to achieve celebrity status, and I’ve heard stories about the kinds of crowds he was able to pull not just at concerts, but just by being in a certain area; one of my friends told me about how he once traveled with BMK in a train in India, and at every stop, there would be hordes of people at the station waiting with garlands for an opportunity to see their favorite musician!fphotograph12

BMK with M. Chandrashekaran (violin) and Umayalpuram K. Sivaraman (mrudangam) – one can see that the year is 1959, and the writing looks like Kannada, so this was probably in Bangalore? EDIT: Thanks to KV Ramprasad and others on Facebook, the sign is actually in Telugu, and reads “Sri Tyagaraja Sangeetha Sabha Anantapuram, established 1959”.

There’s not much I can add to all that has been written about this legendary musician – fortunately his legacy will live on in the numerous recordings that exist of his concerts, as well as the countless commercial albums that he has released, and his movies. Like most of the top musicians of his generation, BMK was a child prodigy, and was adept not just in vocal music, but also in viola and mrudangam.

This is a particularly interesting clip of BMK accompanying the doyen Semmangudi Srinivasa Iyer on the viola – not the usual violin. You can tell it is noticeably bigger than a violin would be. In audience shots, you can see several of today’s top musicians in attendance, including Sanjay Subrahmanyam, T. M. Krishna, and R. K. Sriram Kumar, among others.

Dr. BMK was gifted with a golden voice, which is partly what made his music so great. It is not only resonant, but very fluid – he was able to span 3 complete octaves with ease, and the middle to lower octaves have a very bassy quality that nobody else has. Of course, having a great voice is one thing, and being able to harness it’s full potential is quite another; great musicians with both qualities literally only come once or twice a generation. I do consider myself fortunate that I was able to hear him live just once, in a concert in Sydney organized by Pallavi.

This Kalyani from a concert in Bombay in 1963 demonstrates not just the potential of BMK’s voice, but also his creativity – he employs sruthi bedham (modal shift of tonic) several times not just in the raga alapana, but also in the kalpana swaram, which is much more rare (in fact, I have not heard anyone do it since). Of course, Lalgudi Jayaraman is able to follow effortlessly, and his replies also garner applause several times! I mentioned this particular thani by Umayalpuram Sivaraman sir in a previous post, and it is worth rementioning; the UKS stamp is clearly present from the araichapu phrases to the signature mohara and final korvai in tisra nadai.

Dr. Balamurali’s legacy also lives on in the numerous compositions he authored – he has created numerous thillanas and varnams, in addition to composing krithis in all the 72 melakartha ragams. He also created new ragams such as Mahathi, Lavangi, and others, which did land him into some controversy with vidwan Dr. S. Balachander, who disputed whether those scales could be considered complete ragams at all, since they only had 3 or 4 notes.

This is BMK’s pancha gathi bedha thillana (set to 5 nadais) in 5 “-priya” ragams, as announced in the beginning. This rendition is particularly famous among collectors as it is from his Sangita Kalanidhi concert at the Madras Music Academy, December 1978. This concert also deserves further mention, as the main piece in that concert is an RTP in Kalyani set to a new thalam – Panchamukhi Adi thalam. BMK describes it as doing “gathi bedham” (changing the counts per beat) on the “sashabdha kriyas” (the ‘sounded’ beats when putting the thalam). In other words, only modifying the 1st, 5th, and 7th beats in Adi thalam (those beats are ‘sounded’ since they are downward slaps) to have 2.5 aksharams. Panchamukhi Adi thalam therefore has 12.5 beats. The pallavi set to this thalam is really simple and yet charming, and UKS sir plays a brilliant thani to this new thalam, with his usual razor control. I didn’t upload it because my Soundcloud account is getting full, but it is circulating among collectors. On an interesting side note, I also heard that M. G. Ramachandran (the Chief Minister for Tamil Nadu at the time) was in attendance at that concert!

This is the same pallavi from a different concert with B. V. Raghavendra Rao and Bangalore V. Praveen.

BMK has explored this concept, and sung pallavis in the related trimukhi Adi thalam and navamukhi thalam – in fact, he sang an RTP with the latter in Gamanashrama (53rd melakartha) in the Music Academy in 1980. Gamanashrama is an extraordinarily difficult ragam to sing, as it only came about with the invention of the melakartha scheme in the 17th century. The janya ragams associated with it (Hamsanandi and Purvikalyani) predate it by a long time, and so it is difficult to sing the ragam and maintain its identity unique to Purvikalyani.

EDIT: As pointed out to me yesterday, Hamsanandi is probably younger than Gamanashrama, and upon reflection, this makes sense; the trinity (Thyagaraja, Muthuswami Dikshitar, and Shyama Sastri) did not have any krithis in Hamsanandi. Most of the popular krithis we know in that ragam are actually from more recent composers, such as Harikesanallur Muthaiah Bhagavathar, Papanasam Sivan, and others.

I had mentioned earlier that BMK had acted in a few movies; his Wikipedia page has the complete list (and the fact that his wiki page is so long and detailed is a testament to his fanbase). This song, Oru Nal Podhuma (“is one day enough?”) is one of his hit Tamil cine songs from the movie Thiruvilayadal. This recording is from a concert on 15/2/1985, in Bahrain, and the mrudangam is by none other than Thanjavur Upendran sir. BMK and Upendran sir were extremely close friends, and they had performed thousands of concerts together, including a tour to the US in the 80s. Upendran sir was also one of the people who convinced Balamurali early on to settle in Chennai in other to further his career in Carnatic music.

I’ll leave it here for now. I realized that I had not written any posts on the broad topic of Carnatic music (excluding me making shameless plugs of my clips/concerts) in a while, and this sad news prompted me to write something.

November 18, 2016

Realtalk

Filed under: Chemistry Jobs — sankirnam @ 10:43 am

Please see this video if you want a realistic perspective on the field of chemistry today. He touches on very important topics that I have discussed here in the past, such as:

  • The fact that it is hard to get realistic, accurate information on chemistry employment. Chemjobber remains the most accurate, up-to-date source available online, even if people may find it depressing. ACS information or BLS data is either inflated or not representative of the general population (due to selection bias).
  • Money, unfortunately, IS EVERYTHING. The people who say otherwise are those who have plenty of money, a decent income, and are well off. Being poor limits your opportunities, and as pointed out, lands you in a vicious rut which is difficult to break out of.
  • The flooding of graduate programs. As correctly pointed out, chemistry graduates usually end up in graduate degree programs, whether it is pharmacy, medicine, or chemistry graduate school. This is a structural issue that needs to be resolved at a more fundamental level; the chemistry B.S. needs to be reworked and maybe become more rigorous so that it is worth more.

November 17, 2016

Classics in Organic Chemistry, Part VIII

Filed under: Classics in Organic Chemistry — sankirnam @ 3:46 pm

This paper was further down on my list, but I’ve decided to bump it up and cover it today.

Modern practitioners of organic synthesis or medicinal chemistry will no doubt be aware of how hot fluorine chemistry is now; every issue of JACS, JOC, Organic Letters, Angewandte Chemie, or Chemical Science has at least one paper on the development of new fluorination methodologies. But this was not always the case. Fluorine chemistry used to be considered very esoteric, primarily because of the reagents required (F2, HF, SF4, among others), which also necessitated special reaction conditions and apparatus. This limited the accessibility of fluorinated compounds, and research in this area was primarily done by groups in academia (such as Olah, Seppelt, Christe, Bartlett, Rozen, Haszeldine, Barton) or industry (DuPont, 3M) that had the infrastructure in place to carry out this chemistry.

One of the long-standing challenges in organofluorine chemistry was the development of a mild, effective method to introduce the trifluoromethyl (-CF3) group into organic molecules. I had briefly discussed the challenges in isolating the trifluoromethide anion earlier; this is why the development of nucleophilic trifluoromethylation methods only came about recently. It is necessary to use reagents that act as “pseudo-anions”, and can do a transfer of the -CF3 group under certain conditions.

Prakash and Olah were motivated by their desire to study carbocations that had an electron-withdrawing group α to the cation, such as the ones below:coc_8_1

The synthesis of the precursors for these cations is rather interesting – each involves a different type of chemistry. The α-nitro cation above is prepared by ionizing the gem-dinitro compound (which was synthesized from benzophenone oxime and N2O4), while the α-fluoro cation is prepared from gem-difluorodiphenylmethane, which can be prepared from benzophenone and SF4. The α-cyano cation is prepared by ionizing benzophenone cyanohydrin, which can be easily prepared using a procedure developed by Prof. Paul Gassman with TMSCN and ZnI2.

The α-CF3 cation can be prepared from 2,2,2-triphenylacetophenone and phenylmagnesium bromide, but substituted derivatives are more challenging to prepare; you’ll need substituted derivates of 2,2,2,-triphenylacetophenone which are either challenging to synthesize, of limited commercial availability, or expensive. The easier route would be to start from benzophenone and add a -CF3 to the carbonyl. This was elegantly solved by Prakash, Olah, and Krishnamurti in 1989. They demonstrated that the compound TMSCF3 could undergo nucleophilic trifluoromethyl transfer to carbonyls very readily, under fluoride-ion catalysis. TMSCF3 had first been prepared by Prof. Ingo Ruppert (Germany) a few years earlier, but he had not demonstrated any potential reactions with it.

coc_8_2

This is the proposed mechanism; interestingly, fluoride is not necessarily the only catalyst that can initiate this reaction – Dr. Prakash later showed that carbonates and amine-N-oxides can also act as catalysts. I’m not sure if DMF/imidazole can also initiate this reaction (as they do Corey’s TBS protection), but I’m sure that should also work. One big challenge that still has not been solved is to do this transfer asymmetrically; in other words, a facially-selective trifluoromethyl transfer to carbonyls is still lacking.

This has led to a whole slew of developments which are simply too numerous to list here, leading to TMSCF3 being called the “Ruppert-Prakash reagent”, after the chemists who first synthesized it (Ruppert) and demonstrated its synthetic utility (Prakash). The commercial availability of TMSCF3 also opened up trifluoromethylation to all organic chemists (the original synthesis (adapted from Ruppert’s work) uses CF3Br, which is now banned under the Montreal Protocol). Recently, a postdoc in Prakash’s group (who used to work next to me) came up with an improved synthesis of TMSCF3 from CF3H, which is a byproduct of Teflon manufacturing, and therefore much cheaper and more readily available than CF3Br.

Many, many other types of trifluoromethyl transfer reagents have been developed, and almost all of these use TMSCF3 in their synthesis. The electrophilic trifluoromethylating reagent developed by Togni is illustrative of this. Melanie Sanford has also conducted very nice work in organometallic chemistry studying the reductive elimination of -CF3 from Pd(IV); I particularly remember a very interesting set of papers she had published that showed that “F+” reagents were the only compounds capable of oxidizing the Pd(II) to Pd(IV) and selectively inducing the reductive elimination of the -CF3, because the energy of reductive elimination of -F was greater than that of -CF3. It’s not much though; I think it was 5 kcal or less! Of course, all of these trifluoromethylated metal complexes were synthesized with TMSCF3 as the -CF3 source.

Stephen Buchwald (MIT) also published a couple of papers using TMSCF3 and Pd/Cu complexes for doing -CF3 transfer to a variety of systems.

CuCF3 and AgCF3 are also receiving increased interest now; I talked about CuCF3 earlier. Both of these complexes can be generated in situ from TMSCF3 and appropriate metal salts, and can be used for a variety of transformations, including Sandmeyer-type reactions. I remember that I and my labmates had tried to implement this reaction without much success, and when we saw Goossen’s paper, it seems that the copper counterion is very significant; the reaction only works with CuSCN, which we did not have on hand.

As mentioned earlier, the challenge with developing organometallic reagents for nucleophilic -CF3 transfer (such as LiCF3 or CF3MgBr) is that the CF3 anion is kinetically unstable and tends to undergo fast α-defluorination to yield difluorocarbene. This can be a nuisance, but depending on your needs, can also be synthetically useful. Difluorocarbene can also undergo the usual carbene reactions, such as 2+1 additions to olefins to give gem-difluorocyclopropa(e)nes, as well as insertions into weak bonds, such as S-H or Sn-H. Some friends of mine in Prakash’s group were able to use this to develop useful chemistry – one nice example is the insertion of CF2 carbene so generated into the Sn-H bond of Bu3SnH to make Bu3SnCF2H, which proved to be a useful reagent for -CF2H transfer.

coc_8_3

There was a paper published a couple of years ago by a group in Russia describing the synthesis of TMSCF2H from TMSCF3 by a simple reduction using sodium borohydride. This allows improved access to TMSCF2H (which was otherwise difficult to prepare) and related analogues (such as TMSCF2D, TMSCF2Cl, and others). The challenge with TMSCF2H is that it is more difficult to activate compared to TMSCF3 (it is speculated that the reactive species that does the actual -CF3 transfer is a pentavalent siliconate), accounting for the limited substrate scope (with ketones) in this paper by Jinbo Hu.

Anyway, this is a brief overview of trifluoromethylation chemistry, and I hope the huge impact that Dr. Prakash’s initial paper had is evident – TMSCF3 is now the major source of -CF3 in organic chemistry; most research chemists will not think about how it is produced! This is by no means exhaustive, and numerous reviews (such as this one) are being published about this area of chemistry all the time; check those out if you want more details.

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