Brief reply is sure however you should not, see level 1 under, and lengthy reply is not any its not secure or advisable.
I’d say what you might be proposing which is akin to a brain-wallet model single non-public/public key pair on this query is inadvisable for a number of causes:
1) The largest danger is a scarcity of return change deal with (because of the absence of BIP32) within the case of sending something lower than the complete stability will lead to 100% lack of the distinction (see here for extra )
2) due to the checksum utilized in BIP39 which might alter your pasted binary knowledge (i.e. pasting 256 bits for 24 phrases will later offer you again 264 bits due to the 8-bit checksum that’s appended to the final 11-bit group).
2) Apart from Electrum, most wallets solely enable the importing of mnemonic restoration phrases which might be BIP39 checksum compliant and will not assist you to use an elliptic curve non-public key. For my part, it’s higher to have a checksum compliant mnemonic, regardless of its safety being 256 bits, or Eight bits decrease than 264-bit mnemonic with no legitimate checksum. As a result of it’s extra broadly usable throughout pockets, in case electrum goes down or now not works/supported, and so forth…
3) Decoding dangers: in case you are utilizing a software program that generates the non-public key in Base58 format, there may be potential payload/checksum knowledge hooked up that can improve the chance for errors when changing again to hex manually. In any other case, in case your are acquiring the non-public key in hex format, and are completely positive that it’s the right one when it comes to the elliptical curve calculation to derive the general public key and subsequent bitcoin formatted deal with, you may backup that string of hex characters in quite a lot of methods.
Nonetheless, it might be higher to again up the complete bip 39 Mnemonic crypto vault after which use an offline software to entry any associated wanted non-public key resembling Ian Coleman’s BIP39 tool offline (be aware: I’m a contributor to that Github repo). Though you’ll nonetheless must take care of changing Base58 encoded non-public keys, which I do not reccomend until you recognize 100% how to take action with out error.
4) Error checking: not all 256-bit numbers are legitimate non-public keys, as per the Elliptic Curve specs utilized in Bitcoin (here’s a related applicable post). So there have to be error checking in case you are producing the non-public key your self manually, to ensure the secret’s smaller than the utmost permitted worth
5)Relating to potential collision of personal keys with mnemonics: sure there such collision, and it might be equal to 2 folks randomly selecting or guessing the identical non-public key (i.e., if the preliminary entropy for a mnemonic is identical entropy for an elliptic curve non-public key). In any other case, the keyspace of personal keys is the referenced above in level 4, and no two non-public keys level to the identical deal with on the elliptic curve secp256k1 utilized in Bitcoin. The preliminary entropy vary is 2^256 which is the same as the vary of potential mnemonics 2048^24 minus the mnemonics with invalid checksums (in any other case the keyspace of mnemonics can be
2^264 ==2048^12 with out the checksum requirement however each nonetheless would not change the curve non-public keyspace ).
Once more, I believe it might be safer to comply with the business commonplace and use an HD pockets (which you’d backup with a mnemonic).
P.S. You may additional compress your backup utilizing simply the primary Four letters of every of the 24 phrases, offered that you’re utilizing the English BIP39 model, and concatentate them as a string of 44 characters. However when importing right into a pockets, some do not autocomplete and you might have to lookup phrases manually from the record of 2048 BIP39 English phrases. I take advantage of an ecoding scheme that may additional cut back the 44 charcters to 22 characters (together with particular symbols and numbers) with no info loss, however solely to enhance backups and never as a standalone alternative for BIP39 mnemonics.