Ninhydrin analogs for development of latent fingerprints

Ninhydrin and its analogs give a brief idea of how the chemical reaction occurs while developing latent prints on different challenging surfaces.

1. Ninhydrin Analogs Rituja R. Gharote M.sc II QD and Fingerprints

2. Ninhydrin Ninhydrin was first synthesized in 1910 by Siegfried Ruhemann, a professor of chemistry at the University Chemical Laboratories at Cambridge University. In an effort to synthesize dicarbonyl compounds by the reaction of 1-indanone with p-nitrosodimethylaniline, he isolated 1,2,3- indanetrione (ninhydrin) instead of the desired 1,2-indanedione . shorturl.at/tyBU9

3. Properties of Ninhydrin Ninhydrin is a crystalline solid . It is colorless to pale yellow in color . It is highly soluble in polar solvents such as water and methanol . When heated, the solid becomes pink to red in color . Boiling Point is approximately 125 C . Melting Point is 130–140 C . It decomposes at 241 C. The compound is found as the stable hydrate in the presence of water but will assume a triketone structure in anhydrous conditions .

4. Benzo(f)ninhydrin 01 Thieno(f)ninhydrin 02 5 -Methylthioninhydrin 03 ANALOGS

5. Benzo(f)ninhydrin 01 This compound had been synthesized by Almog in 1982 . 1) C ondens e dimethyl naphthalene-2,3-dicarboxylate with dimethyl sulfoxide. 2) The intermediate sulfoxide is then treated with concentrated hydrochloric acid to yield 2-chloro-2-(methylthio)-1,3-indanedione . 3) 2-chloro-2-(methylthio)-1,3-indanedione is hydrolyzed in boiling water to yield benzo[f]ninhydrin. http://shorturl.at/hmtK6 shorturl.at/tAFGI

6. Synthesis of Benzo(f)ninhydrin Source: shorturl.at/tyBU9 19= dimethyl naphthalene-2,3-dicarboxylate 20= dimethyl sulfoxide 21= 2-chloro-2-(methylthio)-1,3-indanedione 22= benzo[f]ninhydrin

7. Advantages and Disadvantages: Prints developed with this reagent provided dark green marks with a similar sensitivity to that of ninhydrin and provided better contrast on a variety of pink to purple backgrounds. The treatment of benzo ( f ) ninhydrin-developed prints with zinc chloride cause s the formation of a complex that exhibited luminescence properties . Benzo(f)ninhydrin has very low solubility . It is so expensive . It is less effective in terms of results as compared to Ninhydrin. More usage of Reagents.

8. Thieno(f)ninhydrin 2 1) T hiophene-1-carboxylic acid i s deprotonated, then lithiated at the 2-position and added to carbon dioxide to yield thiophene-2,3-dicarboxylic acid. 2) The diacid was reduced with lithium aluminium hydride to the diol, which was converted to the dibromide. 3) Sonication of the dibromide with activated zinc provided the in situ generation of a transient highly reactive diene which was subsequently trapped with 4-cyclopentene-1,3-dione to provide intermediate in excellent yield. 4) Exposure to “Br” in pyridine resulted in aromatization of the 6 -membered ring . 5) O xidation of the 2-position followed by treatment with dimethyl sulfoxide yielded thieno ( f ) ninhydrin.

9. Synthesis of Thieno(f)ninhydrin Source: shorturl.at/tyBU9 32= T hiophene-1-carboxylic acid 33= thiophene-2,3-dicarboxylic acid 34=Thiophene- diol 35=Thiophene-dibromide 36= Intermediate 37= geminal dibromide 38=Thieno(f)ninhydrin

10. Advantages and Disadvantages: This compound displayed a combination of good chromogenic and fluorogenic properties after zinc chloride treatment. shorturl.at/oCGZ7 Reagents are too expensive and are required in great quantity. Results are not that effective as these are one of the primarily synthesized analogs.

11. 5-Methylthioninhydrin (5-MTN) 3 Lennard and co-workers have synthesized 5-methoxyninhydrin. The synthesis began with dimethyl 4-nitrophthalate. Reduction of the nitro group to the amine, was followed by diazotization with nitrous acid in methanol to yield 4-methoxyphthalate. 4-methoxyphthalate mixed with ethyl acetate and sodium hydride and treated with aqueous hydrochloric acid to yield the desired 1,3-diketone. Treatment with p-toluenesulfonyl azide in triethylamine delivered the 2-diazo intermediate. 2-diazointermediate is hydrolyzed with refluxing aqueous tert-butyl hypochlorite to yield 5-methoxyninhydrin.

12. Synthesis of (5-MTN) Source: shorturl.at/tyBU9 23= 4-nitrophthalate 24= amine compond 25= 4-methoxyphthalate 26= 1,3-diketone 27= 2-diazo intermediate 28= 5-methoxyninhydrin

13. Advantages and Disadvantages: The reagent develops print with a more intense fluorescence than ninhydrin-developed prints. It gives more effective results than Ninhydrin. https://www.bvda.com/en/5-mtn Fingerprint developed by (5-MTN) After treatment with zinc chloride, 5-MTN-developed prints do not become orange , but a more reddish colored purple. The fluorescence of the fingerprint is stronger than DFO .

14. Other Ninhydrin Analogs: 1 2 3 4 1,8-Diazafluoren-9-one (DFO) 1,2-Indanedione 9-methyl Anthracene Naphtho ( f ) ninhydrin

15. References: ADD TITLE (2020). Retrieved 3 December 2020, from https://www.researchgate.net/publication/7886048_The_Development_of_Novel_Ninhydrin_Analogues/link/0deec530e46a87d7c8000000/download. (2020). Retrieved 3 December 2020, from https://www.sciencedirect.com/science/article/abs/pii/S0015736888727991. (2020). Retrieved 3 December 2020, from https://www.sciencedirect.com/science/article/abs/pii/S0015736886725103. (2020). Retrieved 3 December 2020, from https://www.ncjrs.gov/pdffiles1/nij/225327.pdf. (2020). Retrieved 3 December 2020, from https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/143867/fsb-chap5-alt-development.pdf.